committee on nfpa 780, and iec61312-1, .iec 62305-4, the deleted documents are no longer in...

TC ROP_ROC Final Ballot Results Cover Letter - February 26, 2009

Committee on NFPA 780

M E M O R A N D U M TO: NFPA 780 Technical Committee on Lightning Protection FROM: Richard Roux DATE: March 26, 2009 SUBJECT: NFPA 780 ROP Letter Ballot Final Results

The Final Results of the NFPA 780 ROP Letter Ballot are as follows: 29 Members Eligible to Vote 5 Ballots Not Returned (C. Batchelor, V. Rakov, D. Reehl, W. Rison, L. Strother) 15 Affirmative on All 8 Negatives on one or more proposals as noted in report (J. Tobias, M. Caie, J. Covino, M. Guthrie, T. Harger, V. Minak, M. Morgan, R. Rapp) 1 Abstentions on one or more proposals as noted in report (R. Daley) Reasons for negative votes, etc. from alternate members are not included unless the ballot from the principal member was not received. According to the final ballot results, all ballot items received the necessary 2/3 required affirmative votes to pass ballot. ATTACHMENT

Report on Proposals – June 2010 NFPA 780_______________________________________________________________________________________________780-1 Log #CP1

_______________________________________________________________________________________________Technical Committee on Lightning Protection,

Review entire document to: 1) Update any extracted material by preparing separate proposals todo so, and 2) review and update references to other organizations documents, by preparing proposal(s) as required.

To conform to the NFPA Regulations Governing Committee Projects.

Delete the following references in IEC Publications, O.2.1:IEC 1024-1, , 1992.IEC 1312-1, , 1995.IEC 1662, , First Edition, 1995.Add the following informational references in O.2.1 in alphabetical order:IEC 62305-1, , 2006.IEC 62305-2, , 2006.IEC 62305-4, , 2006.Revise IEC 62305 in O.1.2.1 to read as follows:IEC 62305-3, , 2006.Revise the 4th paragraph of A.4.18.2.5 as follows:Four Three methods of analysis are commonly used for this determination, although other equivalent analysis can be

used. The four three methods are the following:(1) A risk assessment may be performed in accordance with

and surge protection requirements may be waived if justified by the assessment.(2) The is an analysis to determine the frequency of lightning activity in the

geographic area of the facility. As a rule of thumb, if the flashdensity exceeds one flash per square kilometer per year, surge suppression or other physical protection should beconsidered. Lightning energy can indirectly couple to services at ranges greater than 1 km (0.6 mi) to create potentiallydamaging overvoltages.(23) can also be used as a risk analysis. If these records can

demonstrate the lack of damage on a service due to surges, it can beused to justify low risk of surge damage to a particular system or facility.(34) The starts with a threat electromagnetic field from a nearby

lightning strike and computes the magnitude and rise-time characteristics of transients coupled into services feeding astructure or facility. Based on the computed threat, SPDs can be sized appropriately or omitted, as warranted. Thisanalysis is typically performed for critical communications facilities and in military applications. Electromagneticenvironments for such an analysis can be found in MIL-STD-464,

, and IEC 61312-1, . IEC62305-4,

The deleted documents are no longer in publication and have been superseded by thoseadded.The proposal updates the reference to the IEC standard in A.4.18.2.5 and adds a risk assessment in accordance with

IEC 62305-2 as an approved method for determining where the surge protection requirements may be omitted.

Affirmative: 245 Batchelor, C., Rakov, V., Reehl, D., Rison, W., Strother, L.

RAPP, R.: We have just revised our NFPA 780 Risk Assessment. I see no reason why we need to use the IECdocument for a risk assessment.TOBIAS, J.: My thanks to Mr. Humeniuk & editorial task group for all of the tedious but necessary work.

1Printed on 3/26/2009

Report on Proposals – June 2010 NFPA 780_______________________________________________________________________________________________780-1a Log #CP2


1.1.2 to read as follows:1.1.2* This document shall not cover lightning protection system installation requirements for the following:(1) Explosives manufacturing buildings and magazines(2) Eelectric generating, transmission, and distribution systems.A.1.1.2 to read as follows:A.1.1.2 Electric generating facilities whose primary purpose is to generate electric power are excluded from this

standard with regard to generation, transmission, and distribution of power. Most electrical utilities have standardscovering the protection of their facilities and equipment. Installations not directly related to those areas and structureshousing such installations can be protected against lightning by the provisions of this standard.Lightning protection systems for structures used for production or storage of explosive materials require special

consideration because the contents of such structures are sensitive to arc or spark ignition. Annex K provides guidancefor protection of structures housing explosive materials. Other standards and handbooks that provide guidance formilitary applications are found in Annex O.

1.1.2 and A.1.1.2 are changed as the TC adopted a new Chapter on Protection of Structures HousingExplosive Materials.


_______________________________________________________________________________________________780-2 Log #5

_______________________________________________________________________________________________Harold VanSickle, III, Lightning Protection Institute

Add new text to read as follows:Lightning protection systems shall be installed in a neat and workmanlike manner.

The individual(s) responsible for the installation shall be certified for fitness on the requirements of this Standard by theauthority having jurisdiction.

This addition addresses the problem of unqualified persons making substandard installation ofsystems and components.

1.4 to read as follows:1.4 Mechanical Execution of Work. Lightning protection systems shall be installed in a neat and workmanlike manner

by a qualified person.The submitter's text is too restrictive in a requirement of "certified for fitness."

The TC edits the submitter's text for clarity.The submitter's concern has been addressed by the text change.

Affirmative: 23 Negative: 15 Batchelor, C., Rakov, V., Reehl, D., Rison, W., Strother, L.

MORGAN, M.: I believe that the submitter's text is not overly restrictive. This submission is consistent with otherNFPA documents and allows the AHJ to have some language to qualify the installation contractor. The committeelanguage is ambiguous, vague and unenforceable.


Report on Proposals – June 2010 NFPA 780_______________________________________________________________________________________________780-3 Log #62

_______________________________________________________________________________________________Victor Minak, ExxonMobil Research & Engineering Company / Rep. API Subcommittee on Electrical

EquipmentAdd the following definitions:

A conductive cable or wire that provides a direct electrical connection between the tank shell andtank roof.

A short conductor that is electrically connected to the tank roof and contacts the tank shell.Definition provided for terms used in the body of the 780 document from another API proposal.

New 3.3.7.4 to read as follows:Shunt Conductor. A short conductor used for conduction of the fast and intermediate components of lightning stroke

current, that is electrically connected to the tank roof and contacts the tank shell by scraping or frictional contact.The TC does not accept bypass conductor as the term is not used in the standard.

The TC edits the submitter's text. The change meets the submitter's intent.


MINAK, V.: The Committee Meeting Action has not met the submitter's intent for the proposal, A "BypassConductor," as proposed, is intended to conduct the intermediate to long duration lightning stroke discharge (or toconduct any slow, static charge buildup) and is ineffective for the fast-duration discharge due to its inductance. TheBypass Conductor may be ten or more meters in length and is conductively connected to the tank roof and the tankshell. The term "Bypass Conductor" is used in Proposal 780-66, as modified in API's negative comment. The ShuntConductor definition should be accepted as proposed. A definition should not have an included requirement (accordingto NFPA Style) and the Committee Meeting Action has added a requirement in the definition by the Committee MeetingAction. See also the negative API comment on Proposal 780-66.

MORGAN, M.: The submitter's definition should remain. In the special application to this particular type of structure,this term is important and needs to be included.



_______________________________________________________________________________________________Mitchell Guthrie, Independent Engineering Consultant

Revise text as follows:Suppressed Voltage Rating (SVR). A specific measured limiting voltage rating assigned to a surge protective

device (SPD).Surge Arrester. A protective device for limiting surge voltages by discharging or bypassing surge current; it also

prevents continued flow of follow current while remaining capable of repeating these functions. [70: Article 100]Surge Protective Device (SPD). A device composed of any combination of linear or nonlinear circuit elements

intended for limiting surge voltages on equipment by diverting or limiting surge current which comprises at least onenon-linear component.

Transient Voltage Surge Suppressor (TVSS). A protective device for limiting transient voltages by diverting orlimiting surge current; it also prevents continued flow of follow current while remaining capable of repeating thesefunctions.

Editorial.

Delete 3.3.27.Delete A.3.3.27.Delete 3.3.29.3.3.30 to read as follows:3.3.30 Surge Protective Device (SPD). A device composed of any combination of linear or nonlinear circuit elements

intended for limiting surge voltages on equipment by diverting or limiting surge current which comprises at least onenon-linear component.Delete 3.3.32.Renumber remaining sections.

The TC notes the submitter also intended to delete A.3.3.27.


RAPP, R.: Having Surge Protection Devices (SPD's) in the body of this document is not in the right. It should be inanother NFPA committee. Lightning Protection installers are not educated or licensed to install these products. To putthis responsibility on the LP installers is wrong. If it is retained in this document, it should be in the annex. It similar torequiring an electrician to install plumbing, they are not educated, tested or licensed to do this work.

_______________________________________________________________________________________________780-5 Log #35

_______________________________________________________________________________________________Stephen Humeniuk, Warren Lightning Rod Company

Eliminate hyphen from short-circuit in the following sections: 3.3.35; 4.18.5.1.Committee changes made to delete the Hyphen in order to establish consistency as per the manual of

style.


RAPP, R.: Please see my Comment on 780-4



_______________________________________________________________________________________________John M. Tobias, US Army CECOM

In paragraph 4.1.2 and Figure 4.1.22, change 'roof pitch' to 'roof slope.'Information received from authoritative sources imply NFPA 780s use of the term 'roof pitch' is not

consistent with the building industry. See supporting material for further substantiation.Note: Supporting material is available for review at NFPA Headquarters.

Change "pitch" to "slope" in all incidences in 4.1.2 and Figure 4.1.2.2.4.9 to read as follows:4.9 Conductors.Main conductors shall interconnect all strike termination devices and shall form two or more paths from each strike

termination device downward, horizontally, or rising at no more than 1/4 slope to connections with grounding electrodes,except as permitted by 4.9.1 and 4.9.2.

The TC notes the submitter intended to reference to Figure 4.1.2.2 rather than 4.1.22.The TC also changes "pitch" in 4.9 for consistency.





Revise to read as follows:

****INCLUDE 780_CP_3.doc HERE ****

The TC effects a restructure to various consecutive sections in Chapter 4 for usability. Inclusive aresections 4.6 (new 4.6) through 4.8.9.2.2 (new 4.8.10.2.2).The TC notes that NOTE 1 and NOTE 2 in A.4.7.3.5 are notes to Figure A.4.7.3.5.


RAPP, R.: Parts do not contain NFPA Standard language - such as A.4.6.1 - "Suggestions" are not Standardslanguage. If wanted, put in appendixA.4.7.3.5 - I can not agree on relaxing requirement because "research suggests" This "research" was not presented tothe committee4.8.2.1 - This is completely against the design model adopted by the Standard and hasn't be justified with any scientificresearchLast Page Chart - I can not agree to relaxing the 150' model without substantiation - no scientific testing was presentedto the committee

DALEY, R.: For clarity identify the figure on page 10 as "Figure A.4.7.3.5.GUTHRIE, M.: “I agree with many of the comments concerning the need for an editorial revision of the proposed text.

The proposal consolidated several other proposals and the Comment Phase of the revision cycle must be used to cleanup some of the editorial and clarification of intent issues identified. However, I do not concur that the references to IEC62305 protection levels should be deleted as these provide the technical basis for the requirements. I also disagree withMr. Rapp’s assertion that the “research” referenced in A.4.7.3.5 has not been seen or reviewed by the committee. Thereferenced research was presented during the 2008 Edition development cycle and the information is currently includedin NFPA 780-2008, A.4.7.3.2. There is significant scientific information justifying the proposal and the chart on the lastpage (Figure A.4.7.3.5 as identified by Mr. Daley). Two references summarizing this data best can be found in CIGREElectra No. 41 and CIGRE Electra No.69. These references could be added to Clause O.2.6 to provide the sourceinformation of which Mr. Rapp may looking. Finally, I also disagree with Mr. Rapp’s suggestion that scientific researchwas not provided to justify the proposal included in 4.8.2.1. Dr. Berger provided a presentation during the Pigeon Forgepre-ROP meeting reporting on research that provides the baseline information for the development and approval of thisproposal.”HARGER, T.: In 4.6.1.1, I believe the reference to Section 4.9 is not correct as this refers to conductors. The correct

reference is section 4.6.1.4.4.8.2.1 considers eave heights of 46m or less and gives no guidance for higher roofs.4.8.5.2 references 4.8.2 for requirements for protecting ridges, but there are noneTOBIAS, J.: I would like to thank the Mr. Harger & strike termination task group for the initial proposals and the entire

committee for their work on CP3. Despite tedious details, the entire committee participated to ensure this is atechnically sound and usable proposal.VANSICKLE, III, H.: Par. 4.7.3.1 - references at end of sentence should be changed to 4.7.3.3 & 4.7.3.4.

Par. A.4.7.3.5 and Figure A.4.7.3.5 - there is no explanation in the document of IEC protection levels I through IV whichmakes this discussion and diagram confusing even in the Annex - delete itPar. 4.7.4.3 - the formula for zone of protection is missingPar. 4.8.10 - references at end of sentence should be changed to 4.8.10.1 through 4.8.10.2.2Par. 4.8.10.1 - references at the end of this sentence should be changed to 4.8.1, 4.8.1.1 and 4.8.1.2.


Report on Proposals – June 2010 NFPA 780

_______________________________________________________________________________________________780-7 Log #10


Revise text to read as follows:4.6.1.1 Strike termination devices shall include air terminals, metal masts, permanent metal parts of structures as

described in Section 4.9, and overhead ground wires.Committee changes made to add mandatory text.

See Committee Action/Statement on 780-6a (Log #CP3).


_______________________________________________________________________________________________780-8 Log #12


Section 4.6.1.2 to read as follows:Combinations of these strike termination devices shall be permitted.Renumber subsequent sections4.1.6.1.2 Combinations of these strike termination devices shall be permitted.4.6.1.23 Strike termination devices shall be provided where required by other sections of this standard.4.6.1.34 Metal parts of a structure that are exposed to direct lightning flashes and that have a metal thickness of 4.8

mm (3/16 in.) or greater shall require only connection to the lightning protection system.4.6.1.45 such connections shall provide a minimum of two paths to ground.4.6.1.56 Strike termination devices shall not be required for those parts of a structure located within a zone of

protection.Committee changes made as per MOS section 1.8.3, for only one mandate per paragraph or

subparagraph.





_______________________________________________________________________________________________Thomas R. Harger, Harger Lightning Protection Inc.

Revise heading to read 4.6.2 Air Terminal Height TerminalsRenumber existing section: 4.6.2* 4.6.2.1* "Air Terminal Height..."Renumber existing section: 4.6.3 4.6.2.2 Air Terminal Support... (also renumber sections 4.6.3.1 and 4.6.3.2 to

4.6.2.2.1 and 4.6.2.2.2 respectively to follow above)Renumber existing section: 4.6.4 to 4.6.2.3 Ornaments... (also renumber sections 4.6.4.1 and 4.6.4.2 to 4.6.2.3.1 and

4.6.2.3.2 respectively to follow above)Section 4.6.1 lists other types of strike termination devices that are not referenced in this section. This

renumbering allows for their insertion in subsequent proposals.

See Committee Action/Statement on 780-6a (Log #CP3).The TC edits the submitter's text. The change meets the submitter's intent.


_______________________________________________________________________________________________780-10 Log #92


Add new section as follows:4.6.3 Strike Terminal Masts.4.6.3.1 Strike Protection Masts are used to provide a zone of protection.4.6.3.2 Metal masts shall comply with section 4.6.1.34.6.3.3 Non-metallic masts shall be provided with at least one air terminal and at least one main-size conductor in

accordance with sections 4.8 and 4.9.Section 4.6.1 lists other types of strike termination devices that are not referenced in this section. This

proposal adds requirements for mast-type strike termination devices.





_______________________________________________________________________________________________Simon Larter, Warren Lightning Rod Company

Revise text to read as follows:Air terminals exceeding 600 mm (24 in.) in height above the area or object they are to protect shall be supported at a

point not less than one-half their height, as shown in Figure 4.6.3.2.Clarifies the intent of supporting air terminals against overturning. With the original wording, a 6 ft air

terminal projecting only 12 in above an adjacent vent would not need support. Also, Figure 4.6.3.2 shows the correctintent of the code, and the wording change will reflect this.



_______________________________________________________________________________________________780-12 Log #93


Add new section as follows:4.6.4 Overhead Ground Wires.4.6.4.1 Overhead ground wires are used to provide a zone of protection.4.6.4.2 Over head ground wire material shall be constructed of aluminum, copper, stainless steel, or protected steel

such as copper-clad, aluminum-clad.4.6.4.3 The overhead ground wire material shall be chosen to minimize corrosion from conditions at the site.4.6.4.4 The overhead ground wire shall be sized to have the same cross-sectional area as a main-size lightning

conductor and shall be self-supporting with minimum sag under all conditions.Section 4.6.1 lists other types of strike termination devices that are not referenced in this section. This

proposal adds requirements for overhead wire strike termination devices.






Section 4.7 to read as follows:4.7 Zones of Protection. The geometry of the structure shall determine the zone of protection.

Committee changes made as per MOS section 1.8.3, for only one mandate per paragraph orsubparagraph.



_______________________________________________________________________________________________780-14 Log #14


Section 4.7.1 to read as follows:4.7.1 One or more methods, as described in 4.7.2 through 4.7.4.3.2, shall be used to determine the overall zone of

protection.Committee changes made as per MOS section 1.8.3, for only one mandate per paragraph or

subparagraph.






Section 4.7 to read as follows:4.7 Zones of Protection. The geometry of the structure shall determine the zone of protection.Section 4.7.1 to read as follows:4.7.1 One or more methods, as described in 4.7.2 through 4.7.4.3.2, shall be used to determine the overall zone of

protection.Renumber subsequent sections.Renumber figures 4.7.2.3(a) to 4.7.3.3(a), 4.7.2.3(b) to 4.7.3.3(b), 4.7.2.4(a) to 4.7.3.4(a), and 4.7.2.4(b) to 4.7.3.4(b)

The zone of protection for the following roof types shall include the roof and appurtenances whereprotected in accordance with Section 4.8:(1) Flat or gently sloping roofs(2) Dormers(3) Domed roofs(4) Roofs with ridges, wells, chimneys, or vents

For structures with multiple-level roofs no more than 15 m (50 ft) in height, the zone of protection shallinclude areas as identified in 4.7.32.3 and 4.7.32.4.

The zone of protection shall be permitted to be delineated by is a cone with the apex located at the highestpoint of the strike termination device, with its surface formed by a 45-degree or 63-degree angle from the vertical. basedon that air terminals height above the ground as defined in sections 4.7.3.3 and 4.7.3.4.

Structures that do not exceed 7.6 (25 ft) above earth shall be considered to protect lower portions of astructure located within a one-to-two zone of protection as shown in Figure 4.7.32.3(a) and Figure 4.7.32.3(b).

Structures that do not exceed 15 m (50 ft) above earth shall be considered to protect lower portions of astructure located within a one-to-one zone of protection as shown in Figure 4.7.32.4(a) and Figure 4.7.3p2.4(b).

Task group made changes to comply with MOS1.8.3






4.7.2.2 to change to 4.7.3.2 and read as follows:4.7.3.2 The zone of protection shall be permitted to be delineated by a cone with the apex located at the highest point

of the strike termination device, with its surface formed by a 45-degree angle or 63 degree from the vertical, base onthat air terminals height above the ground as defined in sections 4.7.3.3 and 4.7.3.4

The zone of protection shall be permitted to be delineated by is a cone with the apex located at the highestpoint of the strike termination device, with its surface formed by a 45-degree or 63-degree angle from the vertical.,based on that air terminals height above the ground as defined in sections 4.7.3.3 and 4.7.3.4

Task group made changes to add mandatory text






Change 4.7.3.1 to 4.7.4.1 and read as follows:4.7.4.1 The zone of protection shall include the space not intruded by a rolling sphere having a radius of 150 ft (46 m)

as shown in Figure 4.7.4.1.Renumber caption Figure 4.7.3.3 to 4.7.4.1(A)Move 4.7.3.3 to the annex as explanatory material for section 4.7.4.1 to read as follows:A.4.7.4.1 Figure 4.7.4.1 depicts the 46 m (150 ft) rolling sphere method for structures of selected heights up to 46 m

(150 ft). Based on the height of the strike termination device for a protected structure being 7.6 m (25 ft), 15 m (50 ft),23 m (75 ft), 30 m (100 ft), or 46 m (150 ft) above ground, reference to the appropriate curve shows the anticipated zoneof protection for objects and roofs at lower elevations.Renumber section accordingly

The zone of protection shall include the space not intruded by a rolling sphere having a radius of 46 m (150ft), as shown in Figure 4.7.43.1. (NOTE: Recaption Fig. 4.7.3.3 as Figure 4.7.43.1(a). Also recaption Figure 4.7.3.1(B)as Figure 4.7.3.1 (b)).

Where the sphere is tangent to earth and resting against a strike termination device, all space in the vertical planebetween the two points of contact and under the sphere shall be considered to be in the zone of protection.

A zone of protection shall also be formed where such a sphere is resting on two or more strike termination devicesand shall include the space in the vertical plane under the sphere and between those devices, as shown in Figure4.7.43.1(B).

All possible placements of the sphere shall be considered when determining the overall zone of protection usingthe rolling sphere method.

For structure heights exceeding 46 m (150 ft) above earth or above a lower strike termination device, thezone of protection shall be the space in the vertical plane between the points of contact, and also under the spherewhere the sphere is resting against a vertical surface of the structure and the lower strike termination device(s) or earth.

Figure 4.7.3.3 depicts the 46 m (150 ft) rolling sphere method for structures of selected heights up to 46 m(150 ft). Based on the height of the strike termination device for a protected structure being 7.6 m (25 ft), 15 m (50 ft),23 m (75 ft), 30 m (100 ft), or 46 m (150 ft) above ground, reference to the appropriate curve shows the anticipated zoneof protection for objects and roofs at lower elevations.

The graph shows the protected distance ("horizontal distance") as measured radially from the protected structure.The horizontal distance thus determined shall apply only at the horizontal plane of the "height protected."

Under the rolling sphere method, the horizontal protected distance found geometrically by Figure4.7.43.31(a) ("horizontal protected distance, m" or "horizontal protected distance, ft") also shall be permitted to becalculated using the following formula (units shall be consistent, m or ft): where:

= horizontal protected distance1 = height of the higher roof= rolling sphere radius [46 m (150 ft)]

2 = height of the lower roof (top of the object)Use of this formula shall be based on a 46 m (150 ft) striking distance.for the formula to be valid, the sphere shall be either tangent to the lower roof or in contact with the earth,

and in contact with the vertical side of the higher portion of the structure.In addition, the difference in heights between the upper and lower roofs or earth shall be 46 m (150 ft) or less.

Committee changes made to address the issue of no mandatory text.


Affirmative: 24


Report on Proposals – June 2010 NFPA 7805 Batchelor, C., Rakov, V., Reehl, D., Rison, W., Strother, L.

_______________________________________________________________________________________________780-18 Log #95


Revise text to read as follows:4.7.3.1 The zone of protection shall include the space not intruded by a rolling sphere having a radius of 46 m (150 ft)

the striking distance determined for the type of structure being protected.The present text restricts rolling sphere calculations to spheres with a radius of 46 m (150 ft). This text

allows for other radius spheres based on the striking distance of the lightning stroke.



RAPP, R.: I cannot agree to relax the 150' rolling sphere design model without scientific testing, which has not beensubmitted to the committee to review or discuss. Adopting such a proposal would only bring any user or reviewer toquestion any validity the committee or it's work may have.

_______________________________________________________________________________________________780-19 Log #96


Replace existing text as follows:4.7.3.2* "For structure heights exceeding 46 m (150 ft) the striking distance..."

The present text restricts rolling sphere calculations to spheres with a radius of 46 m (150 ft). This textallows for other radius spheres based on the striking distance of the lightning stroke



COVINO, J.: Leave in the dimensions.RAPP, R.: I cannot agree to relax the 150' rolling sphere design model without scientific testing, which has not been

submitted to the committee to review or discuss. Adopting such a proposal would only bring any user or reviewer toquestion any validity the committee or it's work may have.

GUTHRIE, M.: “The proposal does not delete the values for the radius of the rolling sphere nor does it add anyproposed new radii to the existing models. It simply moves the requirements for the radius of the sphere to a newclause.”




Revise text to read as follows:Figure 4.7.3.3 to be changed to 4.7.4.1 and figure 4.7.3.1(B) to be changed to Figure 4.7.4.1(B). Change references to

those figures in section 4.8.2.2 (formerly the second paragraph of section 4.8.3)Committee changes made to align reference with other changes.



_______________________________________________________________________________________________780-21 Log #97


Revise existing text below formula as follows:R = rolling sphere (striking distance) radius 46 m (150 ft)

Also, delete section 4.7.3.4.1The present text restricts rolling sphere calculations to spheres with a radius of 46 m (150 ft). This text

allows for other radius spheres based on the striking distance of the lightning stroke. Section 4.7.3.4.1 unnecessarilyrestricts the use of the formula.







Renumber existing 4.7.3.4.2 to: 4.7.3.4.1 "For the formula to be valid..."Also, in the same section, re-set heading (A) to new section 4.7.3.4.2. In addition, the difference in height between the

upper and lower roofs on earth shall be 46 m (150 ft)the striking distance or less.

Current text includes an item (A) with no item (B). This renumbering corrects this editorial problem.Removing the hard distances and replacing with "striking distance" allows the formula to be used for other strikingdistances.







Add new text as follows:*4.7.2.5 Structures exceeding 15 m (50 ft) in height that do not exceed 60 m (200 ft) above earth shall be considered to

protect lower portions of a structure located within an angle of 15 degrees from vertical (see Figure 4.7.2.5).A.4.7.2.5 Research indicates that the probability of low amplitude strikes to the vertical side of a structure of less than

60 meters height are low enough that they need not be considered (see IEC 62305-3, 5.2.3.1). It is suggested that awall or surface with a slope characterized by an angle from vertical of no more than 15 degrees be consideredessentially vertical as it relates to the electric field gradient that could result in the generation of streamers.IEC 62305-3, 5.2.3.2 acknowledges that the rules for the placement of strike termination devices may be relaxed to

that equivalent to IEC Lightning Protection Class IV for upper parts of tall structures where protection is provided on thetop of the structure. Figure A.4.7.2.5 identifies the maximum values of protection angle versus Class of LPS based onIEC 62305-3. The 15 degree angle from vertical falls well within the limits specified for a Class IV LPS at a height of 60m (200 ft).NOTE 1 is the height of air-termination above the reference plane of the area to be protected.NOTE 2 The angle will not change for values of below 2 m.Figure A.4.7.2.5 – Maximum values of protection angle corresponding to the class of LPS (taken from IEC 62305-3,

Edition 1)The standard currently does not provide guidance for the use of the protective angle method for

structures of height greater than 50 feet (15 m). Existing requirements for heights between 50 feet and 150 feet willrequire additional protection for tall projections from structures such as steeples that would appear to be not justified.This proposal also attempts to provide guidance on the protection of vertical surfaces on tall structures up to 200 feet.







Revise text to read as follows:Section 4.8.2* Location of Devices on Roofs to be renumbered as 4.8.1 with 4.8.2.3 to be deleted.4.8.1 Pitched Roofs to be deleted.4.8.2.3A to be renumbered as 4.1.2.1 and 4.8.2.3B to be renumbered as 4.1.2.24.1.2.1 to be 4.1.2.34.1.2.2 to be 4.1.2.44.8.2.4 Flat or Gently Sloping Roof Area to be renumbered as 4.8.3Renumber rest of the entire section accordingly

Pitched roofs shall be defined as roofs having a span of 12 m (40 ft) or less and a pitch 1/8 or greater, and roofshaving a span of more than 12 m (49 ft) and a pitch 1/4 or greater.

All other roofs shall be considered gently sloping and are to be treated as flat.As shown in Figure 4.8.2, the distance between strike termination devices and ridge

ends on pitched roofs, or edges and outside corners of flat or gently sloping roofs, shall not exceed 0.6 m (2 ft),Strike termination devices shall be placed on ridges of pitched roofs, and around the perimeter of flat or

gently sloping roofs, at intervals not exceeding 6 m (20 ft).Strike termination devices 0.6 m (2 ft) or more above the object or area to be protected shall be permitted to

be placed at intervals not exceeding 7.6 m (25 ft).

A pitched roof with eave heights of 15 m (50 ft) or less above grade shall require protection for the ridgeonly where there is no horizontal portion of the building that extends beyond the eaves, other than a gutter.

Pitched roofs with eave heights more than 15 m (50 ft) shall have strike termination devices locatedaccording to the 46 m (150 ft) rolling sphere method.

Flat or gently sloping roofs that exceed 15 m (50 ft) in width or lengthshall have additional strike termination devices located at intervals not to exceed 15 m (50 ft) on the flat or gently slopingareas, as shown in Figure 4.8.2.44.8.3(a) and Figure 4.8.2.44.8.3(b), or such area can also be protected using taller airterminals that create zones of protection using the rolling sphere method so the sphere does not contact the flat orgently sloping roof area.

Dormers as high as or higher than the main roof ridge shall be protected with strike termination devices,conductors, and grounds, where required.

Dormers and projections below the main ridge shall require protection only on those areas extending outsidea zone of protection.

Strike termination devices shall be located along the outermost ridges ofbuildings that have a series of intermediate ridges at the same intervals as required by 4.8.2.

Strike termination devices shall be located on the intermediate ridges in accordance with the requirements forthe spacing of strike termination devices on flat or gently sloping roofs.

If any intermediate ridge is higher than the outermost ridges, it shall be treated as a main ridge and protectedaccording to 4.8.2.

Structures that have exterior wall designs that result in irregular roof perimeters shall be treated on an individual basis.The outermost projections form an imaginary roof edge that shall be used to locate the strike termination

devices in accordance with 4.8.2.In all cases, however, strike termination devices shall be located in accordance with Section 4.8, as shown in

Figure 4.8.54.8.6.2.Strike termination devices installed on vertical roof members shall be permitted to use a single main-size

cable to connect to a main roof conductor.The main roof conductor shall be run adjacent to the vertical roof members so that the single cable from the

strike termination device is as short as possible and in no case longer than 4.9 m (16 ft).The connection of the single cable to the down conductor shall be made with a tee splice, as shown in Figure


Report on Proposals – June 2010 NFPA 7804.8.54.8.6.5.

The perimeter of open areas, such as light or mechanical wells, shall be protectedif the open area perimeter exceeds 92 m (300 ft), provided both rectangular dimensions exceed 15 m (50 ft).

Strike termination devices shall be located so that no portion of the structure islocated outside a zone of protection, as set forth in Section 4.7.

Strike termination devices shall be required on all chimneys and vents that are notlocated within a zone of protection, including metal chimneys having a metal thickness of less than 4.8 mm (3/16 in.).

Chimneys or vents with a metal thickness of 4.8 mm (3/16 in.) or more shall require only a connection to thelightning protection system.

The connection for 4.8.84.8.9.1 shall be made using a main-size lightning conductor and a bonding devicethat has a surface contact area of not less than 1940 mm2 (3 in.2) and shall provide two or more paths to ground, as isrequired for strike termination devices.

Required strike termination devices shall be installed on chimneys and vents, as shown in Figure4.8.84.8.9.3, so that the distance from a strike termination device to an outside corner or the distance perpendicular toan outside edge shall be not greater than 0.6 m (2 ft).

Where only one strike termination device is required on a chimney or vent, at least one main-size conductorshall connect the strike termination device to a main conductor at the location where the chimney or vent meets the roofsurface and provides two or more paths to ground from that location in accordance with Section 4.9 and 4.9.2.

Roof top mechanical units with continuous metal housings less than 4.8 mm (3/16 in.)thick such as air conditioning/heating units, metal air intake/exhaust housings, cooling towers, and so forth, shall beprotected by 4.8.109.1 through 4.8.109.2.2.

Air terminals shall be installed in accordance with 4.8.14.1.2.1 and 4.8.2.These shall be mounted on bases having a minimum contact area of 1940 mm2 (3 in.2) each secured to

bare metal of the housing or mounted by drilling and tapping to the unit's frame per 4.16.3.2 and 4.16.3.3.At least two-main-size conductors shall be installed.

The connection shall be made to bare metal at the base or lower edges of the unit using main-sizelightning conductors and bonding devices that have a surface contact area of not less than 1940 mm2 (3 in.2) and shallprovide two or more paths to ground, as is required for strike termination devices.

These two main bonding plates shall be located as far apart as practicable at the base or lower edges ofthe unit's electrically continuous metal housing and connected to the lightning protection system.

Committee changes made to comply with MOS1.8.3.2

4.1.2 to read as follows:4.1.2.1 Pitched roofs shall be defined as roofs having a span of 12 m (40 ft) or less and a slope 1/8 or greater, and

roofs having a span of more than 12 m (40 ft) and a slope 1/4 or greater.4.1.2.2 All other roofs shall be considered gently sloping and are to be treated as flat.4.1.2.3 For purposes of this standard, roof pitches shall be as shown in Figure 4.1.2.3.Change Figure 4.1.2.2 to 4.1.4.3.4.1.2.4 Protection for a shed roof shall be as illustrated for the gable method in Figure 4.1.2.

See Committee Action/Statement on 780-6a (Log #CP3).The TC edits the submitter's text. The change meets the submitter's intent.The TC relocated 4.8.1(A) and (B) to 4.1.2.




_______________________________________________________________________________________________Douglas J. Franklin, Thompson Lightning Protection Inc.

Paragraph 4.8.2.3 (A) - Change "15m (50 ft)" to "46 (150 ft)."Paragraph 4.8.2.3 (B) - Delete current wording - add -"For structures with pitched roof eaves over 150 ft above grade, the sloped area beyond the horizontal protected area

of the higher adjacent air terminals shall be protected in accordance with the rolling sphere method (see 4.7.3.1.B andFigure 4.7.3.3).

The current document contains errors or omissions overlooked in previous editions (1995 onward).1) Pitched roof protection has always been a subset of the 150 ft arc radius concept and has a separate, distinct set of

application rules beyond a blanket application of the "rolling sphere" to any and all structures.2) This proposal, by the addition of new paragraph (B) to paragraph 4.8.2.3 is technically compliant with the sphere

method when the zones of protection created in a horizontal plane from the air terminals above the eave line of astructure are incorporated in addition to the basic rolling sphere. These zones are always present (with the extentdetermined by air terminal height) and effectively raise ground potential to their specific mounting elevation. Thiseffectively renders the eave line to 0 elevation (i.e. grade or ground). This basically explains and reinforces the longstanding acceptability and satisfactory performance of "ridge only" protection while still being within the rolling spheremethod. The current wording in the 2008 edition has changed this viable, traditionally acceptable condition without anyreal justification. In fact, the study by S. Ait-Amar and G. Berger presented to the committee in September 2008 tendsto reinforce this proposal to a certain extent. Even though written around flat roof configurations an approximate parallelexists if the eave line is considered the "roof" line and the air terminal height is considered as the strike termination(s) atthe peak or ridge line.3) As background, from a real world application standpoint, the current wording and criteria have virtually never been

used or applied in practical, actual installations. It has been standard practice for the entire lightning protection systemworld, from installers to engineers to architects and owners to disregard these criteria and accept in their place, the"ridge only" protection method offered by another Nationally Recognized Testing Lab and its associated systemcertification that had accepted that method.4) The ridge only criteria have been the historical basis for all United States lightning protection standards (NFPA 780,

Ul 96A and LPI 175, etc.) for many decades since the early 1900's . There is not, and never has been, a justifiable,statistically verifiable record of damage or losses that would constitute a basis to support the change to the currentwording. This record was never appropriately considered at the time of this change. The current text was acompromise, a poor one at best, that resulted from the early attempts by this committee to more fully incorporate therolling sphere into the 780 document. We didn't get it right then and there is no need to continue this mistake now andinto the future.I have provided sketches for graphic examples related to this issue.Note: Supporting material is available for review at NFPA Headquarters.



HARGER, T.: Submitters substantiation is not valid. The current requirement was based upon accepted lightningmodels at the time. The requirement has not been "disregarded" and has been used in countless "actual" installations.The proposed change is too broad and all encompassing. A proposal that would allow a single air terminal for a 15story building with a footprint of 10000 SF is a drastic change that shouldn't be accepted lightlyMORGAN, M.: A qualifying parameter should be introduced between 50ft and 150ft. The distance from eave to ridge

should have a maximum length associated with it when invoking this section of the standard for air terminal placementon structures with pitched roofs. Additional information and elaboration on this submittal as it applies to pitched roofs ifrequired before this submittal should be addressed by the Committee.RAPP, R.: I cannot agree to relax the 150' rolling sphere design model without scientific testing, which has not been

submitted to the committee to review or discuss. Adopting such a proposal would only bring any user or reviewer toquestion any validity the committee or it's work may have.


Report on Proposals – June 2010 NFPA 780TOBIAS, J.: I do not agree with the interpretation of the rolling sphere method presented as sufficient for this

proposal. The materials presented by Dr. Berger and Mr. Ait-Amar need more careful study as sufficient justification,with calculated examples.

GUTHRIE, M.: Recent information published by Berger seems to support the concept of the proposal but it appearsthat a limit should be set on the span of the pitched roof. A comment on this proposal will be submitted during the ROCphase to address limiting the application of the proposal based on the research currently available.

_______________________________________________________________________________________________780-26 Log #76


Revise text to read as follows:Dormers as high as or higher than the main roof ridge shall be protected with strike termination devices, conductors,

and grounds, where required.Deleted text is redundant.



_______________________________________________________________________________________________780-27 Log #77


Revise text to read as follows:The connection of the single cable to the down conductor shall be made with a tee splice or other fitting listed

for the purpose, as shown in Figure 4.8.5.5.Original text does not allow the universally-used one-bolt fitting as a method of splicing, and seems

artificially restricted to only one type of fitting. Any fitting listed for splicing cables of the appropriate size should beallowable (tee-splice, one-bolt, two-bolt, crimp fastener, etc.). The accompanying figure could be changed to show othermethods of splicing.

The TC upholds its position.The TC intends the requirement for a tee splice.The submitter has not provided adequate technical substantiation.





Revise text to read as follows:Section 4.8.9 to be changed to 4.8.10 and read as follows:4.8.910.1 Air terminals shall be installed in accordance with 4.8.1 4.1.2.1 and 4.8.2

Committee changes made to comply with MOS1.8.3






Delete the following in its entirety:Strike termination devices shall be permitted to be "dead ended", as shown in Figure 4.9.2 with only

one path to a main conductor on roofs below the main protected level, provided the conductor run from the striketermination device to a main conductor is not more than 4.9 m (16 ft) in total length and maintains a horizontal ordownward coursing.Replace with the following new wording:

A "dead ended" main conductor shall be permitted between a single strike termination device or fullsize bonding fitting and a main conductor run under the following conditions:(A) The main sized conductor run to which the dead-end is connected must have a two-way path to ground.(B) At a main protected roof level when the horizontal portion of the dead-end conductor is not more than 8 ft (2.4 m) in

total length.(C) On a roof below the main protected level when the dead-end conductor is not more than 16 ft (4.9 m) in total length

as shown in Figure 4.9.2.(D) All dead end conductor runs shall maintain a horizontal or downward course from the strike termination device to

the connection point with the main conductor run.The current wording deals only with roof areas below the main protected level. The new wording

provides guidance for main level as well.

4.9.2 to read as follows:4.9.2 Dead Ends. A "dead ended" main conductor shall be permitted between a single strike termination device or full

size bonding fitting and a main conductor run under the following conditions:(A) The main conductor run to the dead end shall have a two-way path to ground.(B) The dead end conductor shall not exceed 4.9 m (16 ft) in total length as shown in Figure 4.9.2(B).(C) All dead end conductor runs shall maintain a horizontal or downward course from the strike termination device to

the connection point with the main conductor run.Change Figure 4.9.2 to Figure 4.9.2(B).

The TC changed the 8 ft dead end requirement to permit up to 16 ft.


MORGAN, M.: The committee action fails to meet the intent of the submitter. In changing the requirement, thecommittee has altered the basic faraday box principle of this standard at the most vulnerable part of the structure.There is no need or evidence of need to make this change.RAPP, R.: This proposal limits the use of this exception to a single strike termination device from the originally

worded "devices". I have not seen any scientific testing that would indicate that this exception should be limited to asingle device.TOBIAS, J.: Main protected level is not well defined and I don't believe there was sufficient justification to increase

the dead end to 16 ft.

GUTHRIE, M.: “I concur with the concept but do not agree with that the committee has properly justified changing theallowable dead end run from 8 feet to 16 feet for the main protected level. The term “main protected level” should alsobe defined to ensure proper application.”




Revise text to read as follows:Irregularly-shaped structures shall have additional down conductors as necessary to provide a two-way path from each

strike termination device.Revised for grammar.


_______________________________________________________________________________________________780-31 Log #79


Revise text to read as follows:Underground metallic piping, and electrical system and telecommunication grounding electrodes shall not be

used in lieu of lightning ground electrodes.This provision shall not prohibit the required bonding together of these items as required by 4.14.1.

Moved second clause of paragraph into its own section to comply with MOS. Deleted “required”because of redundancy.

4.13.1.3 to read as follows:4.13.1.3 Underground metallic piping or ground rod type electrodes for electrical, communication, or other systems

shall not be used in lieu of lightning ground electrodes.The TC grammatically changed the submitter's text. The change meets the submitter's intent.

The TC accepts the submitter's text for 4.13.1.4.





Delete 4.13.1.5 Grounding Electrodes shall be copper-clad steel, solid copper, or stainless steel.Add 4.13.2.3 Grounds Rods shall be copperclad steel, solid copper, or stainless steel.

The materials identified in 4.13.1.5 are not generally applicable to all forms of grounding electrodes.For example, a ground ring electrode or radial is specified as a main size lightning conductor, which refers back to Table4.1.1.1. This corrects the information to ground rods.

4.13.2.5 to read as follows:4.13.2.5 Grounds Rods shall be copperclad steel, solid copper, or stainless steel.

The TC accepts deletion of 4.13.1.5.The TC relocates the submitter's text to 4.13.2.5.


TOBIAS, J.: I believe expressing the alternative materials for grounding electrodes (as opposed to ground rods only)is correct as is in the present standard.

_______________________________________________________________________________________________780-33 Log #21


Renumber 4.13.2.1 as 4.13.2(A)Renumber 4.13.2.2 as 4.13.2(B), Renumber Figure 4.13.2.3(B) as Figure 4.13.2.1(B)Renumber 4.13.2.3 as 4.13.2.1Renumber 4.13.2.3 Ground Rod Depth as 4.13.2.1Renumber 4.13.2.4* Multiple Ground Rods as 4.13.2.2, Renumber Annex A.4.13.2.4 to A.4.13.2.2

Ground rods shall be not less than 12.7 mm (1/2 in.) in diameter and 2.4 m (8 ft) long.Rods shall be free of paint or other nonconductive coatings.

The ground rods shall extend vertically not less than 3 m (10 ft) into the earth.The earth shall be compacted and made tight against the length of the conductor and ground rod, as illustrated in

Figure 4.13.2.34.13.2.1(B).Where multiple connected ground rods are used, the separation between any two

ground rods shall be at least the sum of their driven depths where practicable.Task group made changes to comply with MOS1.8.3.2

Delete * after 4.13.2.4Add * after 4.13.2.2.Relocate text of A.4.13.2.4 to A.4.13.2.2.

The TC accepts the submitter's text and relocates A.4.13.2.4 to A.4.13.2.2. The changemeets the submitter's intent.





Revise text to read as follows:The ground rods shall extend as vertically as practicable not less than 3 m (10 ft) into the earth.

Ground rods often do not go in perfectly vertically. Every installing contractor needs a little wiggleroom in order to be able to install ground rods at a slight angle to avoid obstructions in the ground below.

The submitter's text adds no clarity to the section.


_______________________________________________________________________________________________780-35 Log #81


Revise text to read as follows:The encased electrode shall consist of not less than 6 continuous m (20 continuous ft) of bare copper

main-size conductor.

Suggest deleting paragraph because it simply repeats information that is already in .


_______________________________________________________________________________________________780-36 Log #44

_______________________________________________________________________________________________Melvin K. Sanders, Things Electrical Co., Inc. (TECo., Inc.)

Each radial electrode shall be not less than 3.6 m (12 ft) in length and not less than 460 mm (18in.) below grade and shall diverge at an angle not less greater than 90 degrees.

At less than 90 degrees, decreasing angles of divergence results in more of each radial arm-to-earthcurrent dissipation sphere to overlap. Because the same current polarity emanates from those electrode surfaces facingeach other the current is restrained from leaving those surfaces as these polarities reject each other. This would havethe effect of raising the apparent electrode-earth resistance, with the unwanted effect of decreasing, rather thanincreasing, their overall effectiveness.

4.13.5.2 to read as follows:4.13.5.2 Each radial electrode shall be not less than 3.6 m (12 ft) in length and not less than 460 mm (18 in.) below

grade.The change simplifies installation as the 90 degree requirement limits design flexibility.




_______________________________________________________________________________________________Paul Cabot, American Gas Association / Rep. ASC GPTC Z380 - Gas Piping Technology Committee

Revise text as follows:4.14 Common Grounding.4.14.1 General. All grounding media in or on a structure shall be interconnected to provide a common ground potential.4.14.1.1 This interconnection shall include lightning protection, electric service, telephone, and antenna system

grounds, as well as underground metallic piping systems.4.14.1.2 Underground metallic piping systems shall include water service, well casings located within 7.6 m (25 ft) of

the structure, customer owned underground gas piping, underground conduits, underground liquefied petroleum gaspiping systems, and so on.4.14.1.3 Interconnection to a customer owned gas line shall be made on the customer's side of the meter in

accordance with this section and NFPA 54 Section 7.13.4. Bonding to the gas utility's service line is prohibited. Theinstaller shall consult with the local gas utility to locate the termination of the service line.4.14.1.4 Main-size lightning conductors shall be used for interconnecting these grounding systems to the lightning

protection system.ADD A DRAWING:Add a picture, drawing, or schematic indicating the location of the customer owned piping versus gas provider’s piping.ADD A DEFINITION INTO CHAPTER 3 AS FOLLOWS:Service Line. A distribution line that transports gas from a common source of supply to an individual customer, to two

adjacent or adjoining residential or small commercial customers, or to multiple residential or small commercialcustomers served through a meter header or manifold. A service line ends at the outlet of the customer meter or at theconnection to a customer’s piping, whichever is further downstream, or at the connection to customer piping if there isno meter.

Interconnection of lightning protection system electrical grounding media to gas piping is oftenperformed improperly, resulting in both electrical interference and possible interruption of cathodic protection systemsdesigned to protect the integrity of a utility's buried gas piping. Although NFPA 780, Standard for the Installation ofLightning Protection Systems, Section 4.14.1.3 states “Interconnection to a gas line shall be made on the customer’sside of the meter,” installers of lightning protection systems commonly provide for interconnection on the gas provider’spiping. This may result in a failure to establish a common ground for customer owned piping and the gas provider’sfacilities can be compromised. In an effort to ensure the gas provider’s facilities are adequately protected and addressedwith regard to electrical grounding practices, the committee has submitted the recommend revisions.The Gas Piping Technology Committee (GPTC) consists of approximately 90 members with technical expertise in

natural gas distribution, transmission, and gathering systems. Its membership is balanced between gas distributionoperators, gas transmission operators, manufacturers, and general interest personnel such as federal and stateregulators.The GPTC is an independent technical committee and has been an American National Standards Institute (ANSI)

Accredited Standards Committee (ASC) since 1992 and has the designation of ANSI GPTC Z380. The American GasAssociation (AGA) has been the Secretariat to ASC GPTC Z380 since 1990.

4.14.1.3.1 to read as follows:4.14.1.3.1 Bonding shall not be permitted to the utility side of the meter.

The submitter is not referencing NFPA 780-2008; a previous version is being used.In principle ONLY, the TC accepts changing 4.14.1.3 and adds 4.14.1.3.1.The TC does not accept the submitter's text to change 4.14, 4.14.1, 4.14.1.1, 4.14.1.2, 4.14.1.3 and 4.14.1.4The proposal does not comply with 4.3.3(c) of the Regulations Governing Committee Projects in that it does not

contain proposed text or drawing, including the wording/drawing to be added, revised (and how revised), or deleted.


GUTHRIE, M.: I do not agree with the committee statement that the proposal does not contain proposed text.


Report on Proposals – June 2010 NFPA 780Proposed text is shown as underline. I concur with the submitter's suggestion that text identifying the "gas piping" in4.14.1.2 and 4.14.1.3 can be further defined as "customer owned gas piping."

_______________________________________________________________________________________________780-38 Log #60


Add new text as follows:Where galvanic corrosion is a concern or where a direct bond is prohibited by local code, an isolating spark gap shall

be permitted to be utilized provided significant follow current is not likely to be encountered.Clarification of intent.

4.14.1.5 to read as follows:4.14.1.5 Where galvanic corrosion is a concern or where a direct bond is prohibited by local code, an isolating spark

gap shall be permitted.The TC does not accept "significant follow current" as it is not quantified and unenforceable.





Change the reference to “structural steel” to “structural metallic components.”Editorial.

4.16 through 4.16.3.5 to read as follows:4.16 Structural Metallic Systems.4.16.1 General. The structural metal framework of a structure shall be permitted to be utilized as the main conductor of

a lightning protection system if it is equal to or greater than 4.8 mm (3/16 in) in thickness, electrically continuous or ismade electrically continuous by methods specified in 4.16.3.4.16.2 Strike Termination Devices.4.16.2.1 Strike termination devices shall be connected to the structural metal framing by direct connection, by use of

individual conductors routed through the roof or parapet walls to the metal framework, or by use of an exterior conductorthat interconnects all strike termination devices and that is connected to the metal framework.4.16.2.2 Where such an exterior conductor is used, it shall be connected to the metal framework of the structure at

intervals not exceeding 30 m (100 ft).4.16.3 Connections to Framework. Conductors shall be connected to areas of the structural metal framework that have

been cleaned to base metal, by use of bonding plates having a surface contact area of not less than 5200 mm2 (8 in.2)or by welding or brazing.4.16.3.1 Drilling and tapping the metal column to accept a threaded connector also shall be permitted.4.16.3.2 The threaded device shall be installed with at least five threads fully engaged and secured with at least a jam

nut.4.16.3.3 The threaded portion of the connector shall be not less than 12.7 mm (½ in.) in diameter.4.16.3.4 Bonding plates shall have bolt-pressure cable connectors and shall be bolted, welded, or brazed to the

structural metal framework so as to maintain electrical continuity.4.16.3.5 Where rust-protective paint or coating is removed, the base metal shall be protected with a conductive,

corrosion-inhibiting coating.The TC reviewed the submitter's recommendation and changed "steel" to "metal" throughout

this section. The change meets the submitter's intent.





Revise text to read as follows:Where such an exterior conductor is used, it shall be connected to the steel framework of the structure at intervals not

exceeding 30 m (100 ft), on average.For large steel structures with roof members spaced 60 ft apart, current text requires a connection to

every member. Connecting to one at 0 ft, one at 60 ft, and one at 180 ft gives an average spacing of 90 ft, but violatesthe current text. Permitting an average spacing allows flexibility in field installations for conditions in which buildingconstruction may necessitate slightly longer spacings.

4.16.2.2 to read as follows:4.16.2.2 Where such an exterior conductor is used, it shall be connected to the steel framework of the structure at

average intervals not exceeding 30 m (100 ft).The TC edits the submitter's text for clarity. The change meets the submitter's intent.


GUTHRIE, M.: The proposed wording will allow practices that can be dangerous. The clause refers tointerconnection of exterior roof conductors to the structural steel frame. The connection may be to either vertical orhorizontal steel members. The proposal would allow that all roof conductor connections be made at a spacing of 20 feetas long as the overall perimeter distance does not exceed 100 feet average. A maximum value as currently specifiedmust be required. The number of cases where the steel frame of a structure is not available for over 100 feet is notcommon. If such exist, alternative wording can be developed to require connections as close as practicable to availablesteel frame members. To average the spacing is not the answer to such conditions as this can lead to abuse andpossible dangerous arcing above and beyond the existing sideflash calculations.

_______________________________________________________________________________________________780-41 Log #65


Revise text to read as follows:The threaded device shall be installed with at least five two threads fully engaged and secured with at least a jam nut

or similar.Five threads fully engaged for ½ in. all thread means that 0.385 in thick steel is the minimum thickness

to drill and tap. NFPA 70 2580.8(A)(5) and (6) allow not less than two threads. Suggest revised text to harmonizecodes. Also, “at least” deleted to allow for other, just-as-effective methods of securing the threaded device.

The TC upholds its position that 5 threads fully engaged are required.The submitter has not provided adequate technical substantiation and the change would possibly reduce the margin of

safety.The TC notes the submitter provides an incorrect reference to NFPA 70 2580.8(A)(5) and (6).





Revise text to read as follows:The threaded portion of the connector shall be not less than 12.7 9 mm (1/2 3/8 in.) in diameter.

Class I copper air terminals are often drilled and tapped directly into steel on curtain walls. Older LPSinstallations tended to use them as through-roof connectors. Suggest revision to allow for both of these applications.

The TC upholds its position.The submitter has not provided adequate technical substantiation and the change would possibly reduce the margin of

safety.


RAPP, R.: Metal parts of the structure that are only 3/16" thick are allowed for strike termination devices andconductors. To not allow 3/8" threaded copper as part of the connection appears to be illogical at best. The Standardallows a 3/8" copper strike termination device to also be a conductor, I have not seen any technical validation that wouldconfirm that 3/8" threaded copper is not adequate for the purpose and or use as part of a connection.

_______________________________________________________________________________________________780-43 Log #23


Move section 4.18 to the annexThis section is outside the scope of this document. Section 1.2 clearly defines the purpose as

providing for the Safeguarding of persons and property from hazards arising from exposure to lightning. This sectiongoes beyond the scope to include protection of the contents inside of property.


safety.The proposal does not comply with 4.3.3(c) of the Regulations Governing Committee Projects in that it does not

contain proposed text or drawing, including the wording/drawing to be added, revised (and how revised), or deleted.


RAPP, R.: Surge Protection Devices should only be in the annex or more adequately with another NFPA committee.Lightning protection installers are not educated, tested or licensed to install any of these pieces of equipment. It iscomparable to mandating a plumber to be in charge of the installation of all systems that use electricity or electricalsignals. It is impossible for the LPS installer to know all of these systems at the time of the bidding of a project, and theinformation is not forthcoming from the contractors that are bidding these systems, because of competitive reasoning. ALPS installer is a sub of a sub asking for information on the system they are bidding on a project. It does not work andwill not work in this document and committee.

GUTHRIE, M.: “The purpose of this standard is to provide for the safeguarding of persons and property from hazardsarising from exposure to lightning. This cannot be accomplished by ignoring the threat due to lightning-generatedsurges. Such surges may be above and beyond normal switching transients encountered in a structure. It is notnecessary that all provisions of this standard be accomplished by a lightning protection system installer but it isnecessary that the standard address the threat due to lightning-generated surges.




Add new text as follows:4.18.2.4.1 SPDs shall be installed on branch distribution panels 30 m (100 ft) or more from the primary service

entrance panel where the electrical equipment fed by the panel is sensitive to overvoltages and determined to bemission critical or critical to life safety.4.18.2.4.2 SPDs installed on branch panels shall have a minimum nominal discharge current rating ( ) of 10 kA 8/20

ìs per phase.IEEE C62.41-2 identifies scenarios where the inductive coupling of electrical and magnetic fields can

result in surges sufficient to cause damage to sensitive electrical equipment. IEC 62305-4 goes on to identify thatpermanent failure of electrical and electronic systems due to LEMP can be caused by:● conducted and induced surges transmitted to apparatus via connecting wiring;● effects of radiated electromagnetic fields impinging directly onto apparatus itself.Protection at primary and sub-panels (coordinated SPD system) is a recommended technique to reduce these effects.

NEMA LS-1 and IEC 62305-4 suggest that the impedance resulting from 100 feet of wiring from an SPD can besufficient to allow overvoltages of magnitudes that can result in failure of sensitive electrical equipment. In order toreduce the probability of failure of mission critical equipment or equipment that is critical to life safety, SPDs arenecessary where the distance between the SPD at the service entrance exceeds 100 feet.

This standard does not preclude the installation of additional SPDs on branch panels orbranch distribution panels.


GUTHRIE, M.: The committee is remiss if it does not require that surge protection be considered where missioncritical or life safety circuits are located more than 100 feet from the primary service panel where the service entry SPDsare located. IEEE, IEC, and NEMA standards all provide technical substantiation that overvoltages capable of resultingin equipment failure for sensitive equipment can occur where wiring exceeds 100 feet. The requirement is applicableonly to those conditions where the owner or AHJ determines the circuits are mission critical or critical to life safety.4.18.2.5 provides engineering alternatives to the installation of the SPDs.




Move nonmandatory parts of section 4.18.1, to the annex, change 4.18.1* to read as follows:The requirements included within this standard shall be limited to permanently installed surge protective devices

(SPDs).This section provides requirements for surge protection systems installed for the electrical,

communications (including but not limited to CATV, alarm, and data) or antenna systems, or other electrical systemhardware. The requirements included within this standard are limited shall apply only to permanently installed surgeprotective devices (SPDs).

Task group made changes add mandatory text.

4.18.1 to read as follows:4.18.1* General. The requirements for surge protection systems installed for the electrical, communications (including

but not limited to CATV, alarm, and data) or antenna systems, or other electrical system hardware shall apply only topermanently installed surge protective devices (SPDs).

The TC edits the submitter's text. The change meets the submitter's intent to have onlymandatory text in the normative section



_______________________________________________________________________________________________780-46 Log #49


Revise text as follows:4.18.3.1.1 The SPD shall protect against a surges produced by a 1.2/50 μs, 8/20 μs combination waveform generator.

To make it clear that there may be more than one surge experienced in the lifetime of the device (andthat it is tested subsequently).






Revise text as follows:4.18.3.1.2 SPDs at the service entrance shall have an Imax rating of at least 40 kA 8/20 μs per phase or a nominal

discharge current (In) rating of at least 20 kA 8/20 μs per phase.The deleted text is relevant to UL 1449 Edition 2 which will be superceded by UL 1449 Edition 3 at the

time of publication of the standard.






Revise text as follows:Where an SPD has been listed as a transient voltage surge suppressor

(TVSS), The published suppressed voltage rating (SVR) Voltage Protection Rating (VPR) for each mode of protectionshall be selected to be no greater than those given in Table 4.18.4 for the different power distribution systems to whichthey can be connected.

Replace existing Table 4.18.4 with the following table:

To indicate that the Measured Limiting Voltage has been changed to Voltage Protection Rating in UL1449 Edition 3.

INCLUDE 780_L50_Tb 4.18.4_R.doc HEREThe TC includes the Table as it was not provided in the original ROP distribution.



DALEY, R.: New table 4.18.4 not shown.




Revise text as follows:The SPD protection of service entrances shall be listed for the protection of service entrances use Type 1 or

Type 2 SPD in accordance with UL 1449 Edition 3.To identify the correct references to type of devices referenced in UL 1449, Edition 3.

4.18.5.3 to read as follows:The protection of service entrances shall use Type 1 or Type 2 SPD and in compliance with applicable

standards such as UL 1449, UL Standard for Safety for Surge Protective Devices, Edition 3.The TC edits the submitter's text. The change meets the submitter's intent.

The TC includes the updated title to UL 1449.






Section 4.18.6.2 to read as follows:4.18.6.2 The selection of SPDs shall take into consideration aspects such as the frequency, bandwidth, and voltage.Section 4.18.6.3 to read as follows:4.18.6.3 Losses (such as returns loss, insertion loss, impedance mismatch, or other attenuation) introduced by the

SPD(s) shall be within acceptable operational limits.Renumber subsequent sections.4.18.6.2 SPDs shall be selected taking into consideration aspects such as the frequency, bandwidth, and voltage.4.18.6.3 Losses (such as returns loss, insertion loss, impedance mismatch, or other attenuation) introduced by the

SPD(s) shall be within acceptable operational limits.4.18.6.34 SPDs protecting communications systems shall be grounded.4.18.6.34.1* The SPD shall also be bonded to the point of grounding of the electrical service.4.18.6.34.2 If the point of grounding in 4.18.6.43.1 is greater than 6 m (20 ft) away, a supplementary earth electrode or

electrode system shall be installed at the SPD location.4.18.6.34.3 Where provided, a supplementary earth electrode or electrode system shall be electrically bonded to the

facility's main ground electrode system in compliance with NFPA 70, .4.18.6.34.4 SPDs shall not be grounded through a down conductor of the lightning protection system.4.18.6.34.5* SPDs for data and signal line protection shall provide common mode protection.

Task group made changes to comply with MOS 1.8.3

Section 4.18.6.2 to read as follows:4.18.6.2 The selection of SPDs shall take into consideration aspects such as the frequency, bandwidth, and voltage.

The TC edits the submitter's text and clarifies the correct 4.18.6.2 to use. The change meetsthe submitter's intent.





_______________________________________________________________________________________________William Priestley, Priestley Lightning Protection

Revise text as follows:SPDs shall not may be grounded through a down main conductor of the lightning protection system.

The proposed change would satisfy the requirements of 4.18.6.3 and would be far more efficaciousthan the requirements of 4.18.6.3.1 through 4.18.6.3.3.Consider the example of a roof-top antenna or dish that is already bonded to the lightning protection system, and

located hundreds of feet from the electrical service ground.Also, since communications equipment tends to be located on roofs, 4.18.6.3.2 would apply, but would be impossible

to meet in many cases.

The TC upholds its position.The SPD will not function properly if connected to a down conductor. Installation as the submitter proposes could

reverse bias the surge protection device.




_______________________________________________________________________________________________Richard A. Holub, Middletown, DE

Add new Exception No. 1 to 4.20.1.2For structures exceeding 18 m (60 ft) in height, the interconnection of the lightning protection system grounding

electrodes and other grounded media shall be in the form of a ground loop conductor.New Text (below):Exception: Where concrete-encased electrodes are utilized, as allowed in 4.13.3, a separate ground loop conductor is

not required if all metallic media are interconnected to the concrete encased electrode system.NFPA 70 requires the use of concrete encased electrodes in new construction, where available.

Adding a copper ground loop conductor outside the building and then interconnecting this ground loop with theGrounding Electrode may in fact cause galvanic action, with the rebar in the concrete footing becoming the "sacrificialAnode". When this phenomenon occurs, the rebar will corrode, expand, and compromise the footings. A paperdocumenting this was in fact presented at IEEE PCIC last year, 2007 (PCIC-2007-25). In the past, for many of ourbuildings, we've utilized the building steel as the down conductor for a lightning protection system and utilized theconcrete encased rebar in the building footings for the grounding electrode (as allowed in NEC® 250.52(A)(3). Theconcrete encased electrodes have been used for decades (since first being allowed in the early 1970's) as the primarygrounding electrode for many industrial facilities, and adding a copper ground loop conductor when the building is tallerthan some arbitrary height, in this case 60 ft., may in fact cause the primary grounding electrode and footings to fail.This fact is apparently recognized by the authors of NFPA 780 as they included a note in the Appendix A4.14.1indicating that "Isolating Spark Gaps can be used to provide the required bond in those cases where galvanic corrosionis a concern or where a direct bond is not allowed by local code." I don't see any corresponding language, however, inthe NEC® to confirm that the NEC® code panel so agrees that such a connection will satisfy the requirements of250.106. Assuming agreement can be reached among these two codes, I'd also urge the panel to consider making thenote from the Appendix A4.14.1 appear in the body of NFPA 780, where it is enforceable.Note: Supporting material is available for review at NFPA Headquarters.


safety.The TC disagrees with the submitter's substantiation. The corrosion concern between concrete enclosed rebar and

copper wire has been specifically addressed by the Institute of Electrical and Electronic Engineers standard 142,.





Change 4.20.3 to read as follows:Intermediate level potential equalization shall be accomplished by

the interconnection of the lightning protection system down conductors and other grounded media at the intermediatelevels between the roof and the base of a structure in accordance with 4.20.3.1 through 4.20.3.3.Renumber 4.20.3A as 4.20.3.1Renumber 4.20.3B as 4.20.3.2Renumber 4.20.3C as 4.20.3.3

Intermediate level potential equalization shall be accomplished bythe interconnection of the lightning protection system down conductors and other grounded media at the intermediatelevels between the roof and the base of a structure in accordance with 4.20.3.1(A) through 4.20.3.3(C).

Intermediate-loop conductors shall not be required for steel-framed structureswhere the framing is electrically continuous.

The lightning protection system down conductors and other grounded media shall beinterconnected with a loop conductor at intermediate levels not exceeding 60 m (200 ft).

The lightning protection down conductors and other grounded media shall beinterconnected with a loop conductor at intermediate levels not exceeding 18 m (60 ft).

Task group made changes to comply with MOS1.8.3.2





Renumber 4.21.2.1 as 4.21.2(A)Renumber 4.21.2.2 as 4.21.2(B)Renumber 4.21.2.3 as 4.21.2(C)Renumber 4.21.2.4 Structures More Than 40 ft (12 m) as 4.21.2.1Renumber 4.21.2.5 Structures Less Than 40 ft (12 m) as 4.21.2.24.21.1(A).1 through 4.21.1(C).3(A)4.21.1.1 Steel-Framed Structures. Grounded and ungrounded metal bodies exceeding 18 m (60 ft) in vertical

length shall be bonded to structural steel members as near as practicable to their extremities unless inherently bondedthrough construction at these locations.(B)4.21.1.2 Reinforced Concrete Structures Where the Reinforcement Is Interconnected and Grounded in Accordance

with 4.15.3. Grounded and ungrounded metal bodies exceeding 18 m (60 ft) in vertical length shall be bonded to thelightning protection system as near as practicable to their extremities unless inherently bonded through construction atthese locations.(C)4.21.1.3 Other Structures. Bonding of grounded or ungrounded long, vertical metal bodies shall be determined by

4.21.2 and 4.21.3, respectively.4.21.2 Grounded Metal Bodies. This subsection shall cover the bonding of grounded metal bodies not covered in

4.21.1.4.21.2.1(A) Where grounded metal bodies have been connected to the lightning protection system at only one

extremity, the formula shown in 4.21.2.44.21.2.1 or 4.21.2.54.21.2.2 shall be used to determine whether additionalbonding is required.4.21.2.2(B) Branches of grounded metal bodies connected to the lightning protection system at their extremities shall

require bonding to the lightning protection system in accordance with the formula shown in 4.21.2.44.21.2.1 or4.21.2.54.21.2.2 if they change vertical direction more than 3.6 m (12 ft).4.21.2.3(C) Where such bonding has been accomplished either inherently through construction or by physical contact

between electrically conductive materials, no additional bonding connection shall be required.4.21.2.4-1 Structures More Than 12 m (40 ft) in Height.

Grounded metal bodies shall be bonded to the lightning protection system where located within a calculatedbonding distance, , as determined by the following formula:where:

= calculated bonding distance= vertical distance between the bond being considered and the nearest lightning protection system bond= a value related to the number of down conductors that are spaced at least 7.6 m (25 ft) apart, located within a zone

of 30 m (100 ft) from the bond in question, and where bonding is required within 18 m (60 ft) from the top of anystructure

= 1 if the flashover is through air, or 0.50 if through dense material such as concrete, brick, wood, and so forth(B) The value shall be calculated as follows: = 1 where there is only one down conductor in this zone; = 1.5

where there are only two down conductors in this zone; = 2.25 where there are three or more down conductors in thiszone.(C) Where bonding is required below a level 18 m (60 ft) from the top of a structure, n shall be the total number of

down conductors in the lightning protection system.4.21.2.52 Structures 12 m (40 ft) and Less in Height.(A) Grounded metal bodies shall be bonded to the lightning protection system where located within a calculated

bonding distance, , as determined by the following formula:where:

= calculated bonding distance= either the height of the building or the vertical distance from the nearest bonding connection from the grounded

metal body to the lightning protection system and the point on the down conductor where the bonding connection isbeing considered

= a value related to the number of down conductors that are spaced at least 7.6 m (25 ft) apart and located within azone of 30 m (100 ft) from the bond in question

= 1 if the flashover is through air, or 0.50 if through dense material such as concrete, brick, wood, and so forth


Report on Proposals – June 2010 NFPA 780(B) the value n shall be calculated as follows: = 1 where there is only one down conductor in this zone; = 1.5

where there are only two down conductors in this zone; = 2.25 where there are three or more down conductors in thiszone.

Task group made changes to comply with MOS1.8.3.2




_______________________________________________________________________________________________Matthew Caie, ERICO, Inc.

Add new text to read as follows:

Grounded metal bodies shall be bonded to the lightning protection system where located within a calculatedbonding distance, D, as determined by the following formula:

****Insert E780-1 Here****

where:= calculated bonding distance= vertical distance between the bond being considered and the nearest lightning protection system bond= a value related to the number of down conductors that are spaced at least 7.6 m (25 ft) apart, located within a zone

of 30 m (100 ft) from the bond in question, and where bonding is required within 18 m (60 ft) from the top of anystructure

= 1 if the flashover is through air, or 0.50 if through dense material such as concrete, brick, wood, and so forth.or wood. The use of other dielectric materials to reduce the spark-over distance to adjacent metal bodies is permitted. Dcan be reduced by the ratio of the dielectric strength of insulating material to that of air, 3MV/m (1MV/ft)

The value shall be calculated as follows: = 1 where there is only one down conductor in this zone; = 1.5where there are only two down conductors in this zone; = 2.25 where there are three or more down conductors in thiszone.

Where bonding is required below a level 18 m (60 ft) from the top of a structure, n shall be the total number ofdown conductors in the lightning protection system.

Grounded metal bodies shall be bonded to the lightning protection system where located within a calculatedbonding distance, , as determined by the following formula:

****Insert E780-2 Here****

where:= calculated bonding distance= either the height of the building or the vertical distance from the nearest bonding connection from the grounded

metal body to the lightningprotection system and the point on the down conductor where the bonding connection is being considered

= a value related to the number of down conductors that are spaced at least 7.6 m (25 ft) apart and located within azone of 30 m (100 ft)from the bond in question

= 1 if the flashover is through air, or 0.50 if through dense material such as concrete, brick, wood, and so forthor wood. The use of other dielectric materials to reduce the spark-over distance to adjacent metal bodies is permitted. Dcan be reduced by the ratio of the dielectric strength of insulating material to that of air, 3MV/m (1MV/ft)

The value shall be calculated as follows: = 1 where there is only one down conductor in this zone; = 1.5where there are only two down conductors in this zone; = 2.25 where there are three or more down conductors in thiszone.

Dielectric StrengthThe maximum electric field strength that an insulating material can withstand, without experiencing failure of its

insulating properties.Provide guidance to the user of the standard as to the material available to potentially modify the

calculation of the bonding distance if need in the application of the standard. Presently only specific guidance isprovided within the NFPA 780 document for wood, brick and concrete.

The TC notes that the submitter's text for proposed 4.21.2.4(A) does not correlate with the


Report on Proposals – June 2010 NFPA 780formula provided.The TC does not wish to preclude any future consideration of the principle behind the submission of this proposal but

there is insufficient information on its application provided at this time.Dielectric building materials are not listed for the purpose.


CAIE, M.: The Technical Committee notes that the submitter’s text for proposed 4.21.2.4(A) does not correlate withthe formula provided.Please note: no new formula was provided. Formula referenced is that which is given in the current standard.

MORGAN, M.: The practical application of this proposal into the installation of a lightning protection system is veryunclear and appears to be impossible. More studies on the materials, distances and other effects of trying to alterbonding distances with materials that are not part of the permanent building construction are needed. The ICLP paperpresented by Dr. Rakov titled "Bonding Versus Isolating Approaches in Lightning Protection Practice,"(29th ICLP -Uppsala, Sweden), is relevant in this instance. It raises a variety of variables that affect bonding distances which wouldneed to be addressed prior to action on this proposal.TOBIAS, J.: The concept of dielectric shielding/standoff is useful to lightning protection. We need to pursue the

concept and reconcile the bonding calculations to dielectric standoff techniques.

_______________________________________________________________________________________________780-56 Log #67


Revise text to read as follows:Bondings connections shall be made between the lightning protection system and the grounded metal body and shall

not be required to run through or be connected to the isolated metal body.Revised for grammar.


_______________________________________________________________________________________________780-57 Log #68


Revise text to read as follows:Electrically continuous metal structures shall require only bonding to a grounding electrode(s) or electrodes.

Revised for grammar.




_______________________________________________________________________________________________Douglas J. Franklin, Thompson Lightning Protection Inc.

Add text to read as follows:5.8 Roof Top Helipads - Roof top helipads on a protected structure shall be protected in accordance with Chapter 4.

Where this is not possible due to the Authority Having Jurisdiction special criteria the following measures shall beacceptable alternatives to Chapter 4 criteria.A. Bonding of the metal framed perimeter safety net to the Lightning Protection System at 60 ft 0 in. intervals at the

perimeter of the pad shall be permitted to serve as an acceptable strike termination device.B. If the landing area within the perimeter safety net exceeds 50 ft 0 in. in both dimensions, a flat copper or bronze

plate 2 in. minimum in diameter (approx. 3 sq. in area) imbedded or installed flush with the top deck surface andexposed to the air, connected with a two way horizontal or downward path to the roof Lightning Protection System shallbe permitted to serve as the required mid-roof strike termination.C. Where aircraft warning lights are installed at the perimeter of the pad, air terminals shall be installed adjacent to the

fixture and shall be of at least the same height as the fixture or up to 10 in. above the fixture if permitted under theAuthority Having Jurisdiction height requirements for these areas. (Flexible, "tip-over" type air terminals arerecommended.)D. Steel framing at helipad support structure shall be permitted to be used as portions of the Lightning Protection

System.This proposal will provide specialized guidance to insure that the best level of protection possible is

provided to these areas within the height and safety criteria set forth by FAA or other AHJ's.In essence, this wording will put in writing standard industry practices that have been used for some time.

5.9 to read as follows:5.9 Roof Top Helipads - Roof top helipads on a protected structure shall be protected in accordance with Chapter 4.5.9.1 Bonding of the metal frame with a minimum thickness of 4.8 mm (3/16 in.) of the perimeter safety net to the

lightning protection system at 18 m (60 ft) intervals at the perimeter of the pad shall be permitted to serve as anacceptable strike termination device.5.9.2 If the landing area exceeds 15 m (50 ft) in both dimensions, a flat copper or bronze plate 1950 mm2 (3 sq in.)

minimum exposed area where the minimum thickness is 4.8 mm (3/16 in.) installed flush with the top deck surface andexposed to the air, connected with a two way horizontal or downward path to the roof lightning protection system shallbe permitted to serve as the required mid-roof strike termination.5.9.3* Where aircraft warning lights are installed at the perimeter of the pad, air terminals shall be installed adjacent to

the fixture and shall be of at least the same height as the fixture or up to 254 mm (10 in.) above the fixture if permitted.A.5.9.3 to read as follows:A.5.9.3 Flexible, "tip-over" type air terminals are recommended.

The TC accepts the submitter's text but locates it in new 5.9.The TC edits the submitter's text. The change meets the submitter's intent.


VANSICKLE, III, H.: Par. 5.9.1 is poorly worded. Why not try - "Bonding the metallic support framing for theperimeter safety net to the lightning protection system at 60 ft. intervals around the pad perimeter shall serve as striketermination devices when the framing has a minimum thickness of 3/16 in."




Insert new Chapter 7 in place of existing Chapter 7. Increment existing Chapter 7 to becomeChapter 8, and increment existing Chapter 8 to become new Chapter 9. Increment embedded references within existingChapters 7 and 8 to reflect their new numbering position.

****Insert Include 780_L43_R Here****

This proposed new Chapter 7 will provide one clear location for requirements deemed necessary formilitary installation lightning protection.I attempted to copy and paste from the parent file into the assigned block (3), but it was truncated. I have thereforeprovided it under separate cover as a separate “Include File” following NFPA MOS style.

See Committee Action/Statement on Proposal 780-68 (Log #89).


_______________________________________________________________________________________________780-60 Log #29


Delete 7.1.4. Inserted text as the opening paragraph to annex A.7.1.1.7.1.4 In the structures covered in Chapter 7, a spark that would otherwise cause little or no damage might ignite the

flammable contents and result in a fire or explosion.Task group made changes add mandatory text. Relocating non mandatory text to the annex.





Delete 7.3.1.2.Delete 7.3.1.3.Delete 7.3.1.4.Delete 7.3.2.7.3.3 to read as follows:7.3.3 Zone of Protection for Masts, and Overhead Ground Wires.Renumber remaining sections.Relocate 7.3.3.5 and 7.3.3.5(A) to Annex as A.7.3.3.4 to read as follows:A.7.3.3.5 The striking distance is related to the peak stroke current and thus to the severity of the lightning stroke; the

greater the severity of the stroke, the greater the striking distance. In the vast majority of cases, the striking distanceexceeds 30 m (100 ft).Add * after 7.3.3.4.Change 7.3.3.5(B) as 7.3.3.5 to read as follows:7.3.3.5 The zone of protection shall be based on a striking distance of 30 m (100 ft) or less.

The TC effects changes to correlate with the Editorial Task Group recommendation to relocatesections of Chapter 7 to Chapter 4. This correlates with proposal 780-61.


TOBIAS, J.: I would like to thank the entire committee for their work on CP4. Despite tedious details, the entirecommittee participated to ensure this is a technically sound and usable proposal.




This section to be reorganized and renumbered when moved to Section 4.Section to be renamed by removing the word Rods, and

renumbered 4.6.5.Delete 7.3.1.2 and renumbered as 4.6.5.1.Delete 7.3.1.3 to be renumbered to 4.6.5.2.Delete 7.3.1.4 to be renumbered to 4.6.5.3.

Overhead ground wire material shall be chosen to minimize corrosion from conditions at the site.The overhead ground wire selected shall be sized in cross sectionalcross sectional area to a main conductor

and shall be self supporting with minimum sag under all conditions.7.3.1.4 The overhead ground wire shall be constructed of aluminum, copper, stainless steel, or protected steel such as

copper-clad, aluminum-clad, lead clad, or galvanized steel.

Overhead ground wire material shall be chosen to minimize corrosion from conditions at the site.The overhead ground wire selected shall be sized in cross sectional area equal to that of a main conductor and

shall be self supporting with minimum sag under all conditions.The overhead ground wire shall be constructed of aluminum, copper, stainless steel, or protected steel such as

copper-clad, aluminum-clad, lead-clad, aluminum conductor steel reinforced (ACSR) or galvanized steel.Task group made changes to comply with MOS1.8.3.2.



_______________________________________________________________________________________________780-62 Log #37


This section to be reorganized and renumbered when moved to section 4.Section to be renamed by removing the word Rods, and

renumbered 4.6.5.Delete 7.3.1.2 and renumbered as 4.6.5.1.Delete 7.3.1.3 to be renumbered to 4.6.5.2.Delete 7.3.1.4 to be renumbered to 4.6.5.3.

Task group made changes to comply with MOS1.8.3.2.






Revise text to read as follows:The overhead ground wire selected shall be sized in cross-sectional area equal to that of a main conductor and shall

be self supporting with minimum sag under all conditions.Revised for grammar.



_______________________________________________________________________________________________780-64 Log #32


Revise text as follows:The zone shall be based on a striking distance of 30 m (100 ft) or less.

* The striking distance is related to the peak stroke current and thus to the severity of the lightning stroke; thegreater the striking distance.

In the vast majority of cases, the striking distance exceeds 30 m (100 ft).Accordingly, tThe zone of protection shall be based on a striking distance of 30 m (100 ft) or less is protected.

Task group made changes add mandatory text.



_______________________________________________________________________________________________780-65 Log #70


Revise text to read as follows:The zone of protection afforded by any configuration of masts or other elevated, conductive grounded objects

shall be determined.

This information is inherent in 7.3.1.1, so this paragraph is redundant and unnecessary.




_______________________________________________________________________________________________Victor Minak, ExxonMobil Research & Engineering Company / Rep. API Subcommittee on Electrical

EquipmentRevise text to read as follows:

. Where floating roofs utilize hangers located within a vapor space, the roof shall beelectrically bounded to the shoes of the seal through a direct electrical path at intervals not greater than 3 m (10ft) on thecircumference of the tank.(A) These shunts shall consist of flexible Type 302, 28-gauge [0.4 mm x 50 mm (1/64 in. x 2 in)] wide stainless steel

straps or the equivalent in current-carrying capacity and corrosion resistance.(B) The metallic shoe shall be maintained in contact wit the shell and without opening (such as corrosion holes)

through the shoe.(C) Tanks without a vapor space at the seal shall not require shunts at the seal.(D) Where metallic weather shields cover the seal, they shall maintain contact with the shell.(E) Where a floating roof is equipped with both primary and secondary seals, the space between the two seals could

contain a vapor-air mixture within the flammable range; therefore, if the design of such a seal system incorporateselectrically conductive materials and a spark gap exists within that space or could be created by roof movement, shuntsshall be installed so that they directly contact the tank shell above the secondary seal.(F) The shunts shall be spaced at intervals not greater than 3 m (10 ft) and shall be constructed so that metallic contact

is maintained between the floating roof and the tank shell in all operational positions of the floating roof.. For tanks that have metallic external floating roofs storing liquids which can result in

periphery vapor-air mixtures within the flammable range, the floating roof shall be directly bonded to the tank shell.(A) For conduction of the fast and intermediate components of lightning stroke current, shunt conductors shall be used

for the connection between the floating roof and tank shell.(1) The shunt conductors and connections shall be submerged at least 0.3m (1 ft) below the surface of the

liquid product and shall have as direct a path as possible from the bottom of the conductive floating roof to thetank shell.

(2) The shunt conductors shall be spaced at intervals no greater than 3m (10 ft) around the perimeter of thefloating roof.

(3) The shunt conductors shall consist of a self adjusting, stainless steel conductor of at least 20 mm2 (0.031in2) cross sectional area or of other conductors of equivalent current carrying capacity and corrosion resistance. Theminimum width of the shunts shall be 10 mm (0.4 in). The shunts shall not interfere with the function of the floatingroof seal assembly.(B) For conduction of the intermediate and long duration components of the lightning stroke current, bypass conductors

shall be installed between the floating roof and tank shell.(1) A minimum of two bypass conductors shall be connected between the floating roof and tank shell.(2) The maximum end-to-end resistance of each bypass conductor shall be 0.03 ohms.(3) The bypass conductors and termination connections shall be positioned and of sufficient flexibility,

cross sectional area, and corrosion resistance to have a service life of 30 years minimum.(C) Any parallel conducting paths in the seal assembly components, e.g., springs, scissor assemblies, seal

membranes, etc., shall be electrically insulated between the tank shell and floating roof.In the existing NFPA 780 text for this section, shunts are required to be installed on floating roof tanks

above the seal at 3 meter (10 feet) spacing around the tank perimeter. The purpose of these shunts is to provide aconductive path from the tank floating roof to the tank shell. Tests conducted for the API RP 545, "Lightning Protectionfor Above Ground Storage Tanks", Task Group have shown that these shunts can generate showers of incendiarysparks during lightning strikes. If there is a gap between the seal and the tank shell and a flammable mixture is presentduring a lightning strike, a tank fire may result.The API RP 545 Task Group has conducted tests to evaluate alternative methods of providing a conductive path

between the tank floating roof and the tank shell to meet the intent of NFPA 780.Following is a summary of the test results:· Testing demonstrated that for long duration current (~0.5 seconds), the magnitude of sparking and other

effects was clearly reduced by having a parallel roof bonding conductor (termed a "Bypass Conductor"). Theeffectiveness of the strap is determined by its resistance, since any arcs will extinguish if the voltage drop along theconductor is <14V.


Report on Proposals – June 2010 NFPA 780· A bypass conductor alone, without shunt conductors, is not effective in conducting the fast high energy

components of lightning, even with several installed.· Testing demonstrated that, with a combination of a 20 mm depth submerged shunt conductor and 10m?

bypass cable, there were no ignitions of the butane-air diagnostic gas. Occasionally, however, small pieces of burningmetallic particles from the submerged shunt floated up and reached the oil surface. To avoid this potential source ofignition, further testing was done with the shunt submerged lower into the liquid. A shunt depth of 0.3 m (1 ft) resulted inno incendiary sparks reaching the liquid surface during the tests. A 1 mm (0.04 in) insulated spacer between the shuntand the tank shell significantly reduced arcing for tests applying current of long duration (~0.5 seconds) when a parallelbypass conductor path was provided for the current.· Inductance of the roof bypass conductor increases the voltage at the roof/shell interface during a rapid increase

or decrease of current (V=L(di/dt)), as occurs during the "fast" (100 µsec) and "intermediate" (5 msec) duration current,increasing the arcing the roof /shell interface.Based on these test findings and historical observations, we have the following conclusions and preliminary

recommendations:· Based on relevant test observations, it is reasonable to conclude that shunts can be the ignition source for rim

fires, especially if there is a gap between the secondary seal and the tank shell.· The best defense against lightning ignitions is the absence of flammables; e.g., a tight secondary seal.· Standard shoe seal designs have seal assemblies which could provide parallel metallic current paths through

the hanger mechanism to any submerged shunt conductor. These multiple paths to ground present the potential ofarcing in or around the vapor space without some type of modification. These need to be insulated from the tank floatingroof to allow current to take a preferential path either through the shunt conductors or through the bypass conductors.· Primary seal hanger mechanisms can be a source of sparking when located in the vapor space and required to

be insulated from the tank floating roof to allow current to take a preferential path either through the shunt conductors orthrough the bypass conductors.

7.4.1.2 to read as follows:7.4.1.2* Floating-Roof Tanks. Metallic external roofs shall be directly bonded to the tank shell.7.4.1.2.1 Conductors shall be used for the connection between the floating roof and tank shell.7.4.1.2.1.1 The shunt conductors and connections shall be submerged at least 0.3m (1 ft) below the surface of the

liquid product.7.4.1.2.1.2 The shunt conductors and connections shall provide as direct a path as practicable from the bottom of the

conductive floating roof to the tank shell.7.4.1.2.1.3 The shunt conductors shall be spaced at intervals no greater than 3m (10 ft) around the perimeter of

the floating roof.7.4.1.2.1.4 The shunt conductors shall consist of a self adjusting, stainless steel conductor of at least 20 mm2 (0.031

in2) cross sectional area or of other conductors of equivalent current carrying capacity and corrosion resistance.7.4.1.2.1.5 The minimum width of the shunt conductors shall be 10 mm (0.4 in).7.4.1.2.1.6 The shunt conductors shall not interfere with the function of the floating roof seal assembly.7.4.1.2.2* Conductors shall be installed between the floating roof and tank shell.7.4.1.2.2.1 A minimum of two conductors shall be connected between the floating roof and tank shell.7.4.1.2.2.2 The maximum end-to-end resistance of each conductor shall be 0.03 ohms.7.4.1.2.2.3 Stainless steel shall be permitted.7.4.1.2.2.4 The conductors and termination connections shall be positioned and of sufficient flexibility, cross sectional

area, and corrosion resistance to provide a service life of 30 years minimum.7.4.1.2.2.5 The conductor total cross sectional area shall be at least equal to a main size conductor.7.4.1.2.3 Any parallel conducting paths in the seal assembly components, (e.g., springs, scissor assemblies, seal

membranes, etc.), shall be electrically insulated between the tank shell and floating roof.A.7.4.1.2.2 The purpose of the conductor is for conduction of the slow and intermediate components of lightning stroke

current.The TC edits the submitter's text. The change meets the submitter's intent.


MINAK, V.: The concepts for the application of the"shunt conductor" and "bypass conductor," with the definitions asproposed by API in Proposal 780-3, need to be retained to meet the intent of this proposal.


Report on Proposals – June 2010 NFPA 780Using the definitions, as proposed by API in Proposal 780-3:Bypass Conductor. A conductive cable or wire that provides a direct electrical connection between the tank shell andtank roof.Shunt Conductor. A short conductor that is electrically connected to the tank roof and contacts the tank shell.Recommend that the Committee Meeting Action for 7.4.1.2 be modified to read as follows:7.4.1.2* Floating-Roof Tanks. Metallic external roofs shall be directly bonded to the tank shell.

7.4.1.2.1* Shunt Conductors. Shunt conductors shall be used for the connection between the floating roof and tankshell.7.4.1.2.1.1 The shunt conductors and connections shall be submerged at least 0.3m (1 ft) below the surface of the liquidproduct.7.4.1.2.1.2 The shunt conductors and connections shall provide as direct a path as practicable from the bottom of theconductive floating roof to the tank shell.7.4.1.2.1.3 The shunt conductors shall be spaced at intervals no greater than 3m (10 ft) around the perimeter of thefloating roof.7.4.1.2.1.4 The shunt conductors shall consist of a self adjusting, stainless steel conductor of at least 20 mm2 (0.031in2) cross sectional area or of other conductors of equivalent current carrying capacity and corrosion resistance.7.4.1.2.1.5 The minimum width of the shunt conductors shall be 10 mm (0.4 in).7.4.1.2.1.6 The shunt conductors shall not interfere with the function of the floating roof seal assembly.7.4.1.2.2* Bypass Conductors. Bypass conductors shall be installed between the floating roof and tank shell.

7.4.1.2.2.1 A minimum of two bypass conductors shall be connected between the floating roof and tank shell.7.4.1.2.2.2 The maximum end-to-end resistance of each bypass conductor shall be 0.03 ohms.7.4.1.2.2.3 Stainless steel shall be permitted.7.4.1.2.2.4 The bypass conductors and termination connections shall be positioned and of sufficient flexibility, crosssectional area, and corrosion resistance to provide a service life of 30 years minimum.7.4.1.2.2.5 The bypass conductor total cross sectional area shall be at least equal to a main size conductor.7.4.1.2.3 Insulation of Seal Assembly. Any parallel conducting paths in the seal assembly components, (e.g., springs,scissor assemblies, seal membranes, etc.), shall be electrically insulated between the tank shell and floating roof.A.7.4.1.2.1 The purpose of shunt conductors is for conduction of the fast and intermediate components of lightning

stroke current.A.7.4.1.2.2 The purpose of the bypass conductor is for conduction of the slow and intermediate components of lightningstroke current.

LANZONI, J.: Recommend revising sections 7.4.1.2.2.1 and 7.4.1.2.2.2 to agree with the most current version ofAPI-545, as follows:7.4.1.2.2.1 Change to, “Conductors should be spaced every 100 feet around the tank circumference.” On a large tank,using only two conductors is insufficient to carry the intermediate and long components of the lightning strike currentwithin a short enough time to prevent arcing. The revised statement agrees with API-545.7.4.1.2.2.2 Amend existing statement to read, “The maximum end-to-end resistance of each conductor shall be 0.03ohms, and each conductor shall be of the minimum length necessary to permit full movement of the floating roof.” Thestatement encourages the use of short conductors, which have lower resistance than unnecessarily long conductors andhence better performance under lightning conditions. The phrase “shall be of the minimum length necessary to permitfull movement of the floating roof” is included in the most current version of API-545.TOBIAS, J.: Thanks to Mr. Minak and API for this significant action using science-based results. I think this will

significantly improve protection for floating roof tanks.VANSICKLE, III, H.: Par. 7.4.1.2.2 - Add the word "Main" to begin sentence. This differentiates between these

conductors and the shunt conductors, since the Committee did away with the word "bypass".Par. 7.4.1.2.2.1 - Is there ever more than 2 main conductors, and under what circumstances? Should this refer back to4.10.10 Number of Down Conductors? A second issue with this paragraph - Does the conductor have to be connectedat or near the shell base, or maybe within 12 ft. of the base, or could it connect anywhere on the shell (like the top rimdown to a floating roof)?Par. 7.4.1.2.2.4 - requiring a service life of 30 years minimum looks like a product liability lawsuit waiting to happen.What if someone can develop a product for an installed cost of 50% that lasts "only" 27 years - it wouldn't meet theStandard? I think we can specify resistance, cross section, flexibility, insulation, even inspection and maintenance - butthe "30 years minimum" should be deleted.



_______________________________________________________________________________________________780-67 Log #71


Revise text to read as follows:Metallic tanks with wooden or other nonmetallic roofs shall not be

considered self protecting, even if the roof is essentially gastight and sheathed with thin metal and with all gas openingsprovided with flame protection.

Original wording was odd, trying to legislate what a structure can be. Suggest revised wording tomake more grammatical and physical sense.





Add new Chapter 8 as follows:

This Chapter provides the minimum requirements for lightning protection of structures housing explosivematerials.

The provisions of this chapter shall not be required for structures housing Division 1.4 materials, for structureshousing explosives of net explosives weight (NEW) of 25 pounds or less, or where exclusion is justified by a riskassessment.

The risk assessment process found in NFPA 780 Annex L may be used for facilities provided that it isadequately documented.

This chapter shall not apply where it conflicts with airfield or flightline operations, as determined by theauthority having jurisdiction.

Lightning protection systems shall not be required where the following conditions are met:(1)* The facility is served by an approved local lightning warning system as determined by the authority having

jurisdiction, and the lightning warning system shall permit explosives operations to be terminated before a thunderstormis within 16 km (10 miles) of the installation.

Data by R.E., and R.L. Holle, (1999) suggests at least 9.6 -12.8 km (6-8 mile) minimum warningdistance is required to ensure no significant damage from a lightning strike.(2) All personnel are evacuated to a shelter providing adequate protection.(3)* The resulting damage and loss from a lightning strike is acceptable to the authority having jurisdiction.

Annex L provides guidance for performing a facility risk assessment.(4) The facility contains only explosive materials that cannot be initiated by lightning, and where no fire hazard exists,

as determined by documented tests and analyses and approved by the AHJ.(5) Personnel are not expected to sustain injury; there will be a minimal economic loss to the structure, its contents, or

the surrounding facilities; and the resulting damage and loss from a lightning strike is acceptable to the AHJ.Where lightning protection is not installed on a facility, the reasons for not protecting the facility shall be

documented and kept with related risk acceptance or site approval documentation.For those locations where a LPS is not installed, bonding and surge suppression shall be installed as

described in 4.18, 8.5, and 8.7.

Lightning protection systems designed to protect structures housing explosives shall bebased on a striking distance of 30.5 m (100 ft.), as discussed in 7.3.3.

Where the effects of electromagnetic coupling are of concern, a mast or overheadwire (catenary) system shall be installed.

Buildings containing explosives shall have lightning protection consisting of one ormore of the types given in 8.3.1 through 8.3.4.

Where optimum protection for structures housing explosives is required (asdetermined by the AHJ), a grounded, continuously conductive enclosure, as shown in Figure 8.3.1, shall be used.

The best method to protect extremely sensitive operations from all sources of electromagnetic radiation isto enclose the operations or facility inside a metallic (“Faraday-like”) cage. A metallic (“Faraday-like”) cage is anenclosure composed of a continuous grid of conductors, such that the voltage between any two points inside theenclosure is zero when immersed in an electrostatic field. A metallic cage or Faraday shield LPS is one where theprotected volume is enclosed by a heavy metal screen (i.e., similar to a birdcage) or continuous metallic structure withall metallic penetrations bonded. The lightning current flows on the exterior of the structure not through the interior. A“Faraday—like” shield (which is not an ideal Faraday cage) is formed by a continuous conductive matrix that is properlybonded and grounded.A freestanding structure that is determined by the AHJ to be a metallic cage or “faraday-like” shield may not require

either grounding systems or strike termination device. Using of a strike termination system on these structures providesa preferred attachment point for lightning and may prevent structural damage, such as concrete spall, from directlightning attachment.


Report on Proposals – June 2010 NFPA 780The intent of this type structure is to prevent the penetration of lightning current and related electromagnetic field into

the object to be protected and prevent dangerous thermal and electrodynamics effects of current as well as dangeroussparking and overvoltages for electrical and electronic systems. Effective lightning protection is similarly provided bymetallic structures such as those formed by the steel arch or the reinforcing steel in the walls and floors of earth-coveredmagazines (also referred to as bunkers, huts or igloos) if the steel reinforcement is bonded together and it meets thebonding resistance of 8.6.6.

***Insert Figure 8.3.1 Metallic (Faraday-like) Cage Here***

Mast-type systems shall be designed as specified in 7.3.A mast-type LPS shall be permitted to be remote from the structure in order to provide a primary

attachment point for a lightning discharge.The isolation of the down conductors from the structure will reduce the magnetic field strength in the

structure and the probability of a sideflash from a down conductor.Metallic masts shall be a minimum diameter of 16 mm (5/8 in.).Wooden masts shall have a strike termination device or metal cap connected to ground by at least one

down-conductor.For wooden masts using a pole guy wire as a down conductor, the guy wire shall be a continuous metal

cable without any ceramic or insulating sections.Each metallic guy cable shall be bonded at its lower end to the ground ring electrode.

Grounding of masts shall comply with the requirements of 7.3.3.Metallic masts shall be grounded as shown in Figure 8.3.2.2.2.

***Insert Figure 8.3.2.2.2 Connection of Metallic Masts to Ground Ring Electrode Here***

Catenary systems shall be designed as specified in 7.3.3 and as shown inFigure 7.3.3.2 (b).

Integral lightning protection systems shall be installed as specified in Chapter 4, except asmodified below.

Strike termination devices spacing dimensions based upon the 30.5 m (100 ft.) rolling sphere method(RSM) with terminals 0.3 m (12 in.) tall is 7.6 m (25 ft.) at the center of the roof, 6.1 m (20 ft.) at the roof perimeter, and0.6 m (2 ft.) set-back from the outer end of roof ridges. For those 0.6 m (24 in.) tall, the dimensions increase to 12 m (35ft.) at the center of the roof, 6.1 m (20 ft.) at the roof perimeter, and 0.6 m (24 in.) set-back from the outer end of roofridges.

Bonding connections and conductor splices shall not be painted.

A ground ring conductor shall be required for all lightning protection systems on buildings containingexplosives, with all down conductors, structural steel, ground rods, and other grounding systems connected to theground ring conductor as shown in Figures 8.4.1(a) and 8.4.1(b).

***Insert Figure 8.4.1(a) Main and Additional Grounding Systems for Explosives Facilities Here***

***Insert Figure 8.4.1(b) Single Ground Ring Electrode for Explosives Facilities Here***

A ground ring electrode shall not be required for structures with areas of 46.5 m2 (500 ft2) or less orthose that can be protected by a single mast or air terminal.

A ground ring electrode shall not be required for portable structures meeting the provisions of 8.5.5.Ground rods shall comply with Section 4.13.2, except as modified below.

Ground rods shall be sized no less than ¾” x 10’.


Report on Proposals – June 2010 NFPA 780Ground rods shall be buried with their upper end no less than 610 mm (24 in.) below finished grade.

Concrete encased electrodes shall comply with Section 4.13.3.Ground ring electrodes shall be uninsulated cables meeting or exceeding the

requirements for Class II conductors.In soils where highly corrosive soils are encountered, larger cables shall be permitted.Ground ring electrodes shall be augmented with a minimum of two ground rods meeting the requirements of

Section 4.13.2.4.The ground ring electrode shall be installed no less than 0.9 m (3 ft.) and no more than 2.4 m (8 ft.) from

building foundation or footing.Radials shall comply with the requirements of section 4.13.5.

Ground plate electrodes shall comply with 4.13.6.Chemical grounds installed for the specific purpose of providing electrical contact with the

earth, or a conductor immersed in nearby salt water shall be permitted.

Bonding requirements for the protection of structures housing explosive materials shall comply withSection 4.19 and 4.21 as applicable.

Sideflash distances shall be calculated using the method in Section 4.21.2.4(A).Any isolated metallic masses within the sideflash separation distance shall be bonded

to the lightning protection system.Metallic masses with a surface area of less than 0.26 m2 (400 in2) or a volume of less than 1.64 x 104 cm3

(1000 in3) shall not be required to be bonded.Direct bonding techniques shall include the following:

(1) Welding(2) Brazing(3) Bolting(4) Riveting

Soft soldering shall not be permitted.Self-tapping screws shall not be used for bonding purposes in explosives facilities.After completion of the joining process the bond region shall be sealed with appropriate protective agents to

prevent bond deterioration through corrosion of the mating surfaces.Fences shall have bonding across gates as well as other discontinuities and shall be bonded to the

lightning protection system ground ring electrode to provide electrical continuity.Bonding shall be made between the fence and the structure or facility where the fence is located within 1.9 m

(6 ft) of the structure or facility.All gateposts shall be grounded to a ground rod.

Gateposts shall have bonding conductors run between them, buried not less than 38 mm (18 in.).Gates shall be bonded to grounded gateposts.

Wooden posts supporting horizontal single metallic strands shall have down conductors extending the fullheight of the wooden pole and bonded to each single strand to form a continuous path to ground.

Where non-metallic coated fencing is supported by metallic posts the posts shall be connected together at theirtop by a rigid metallic bar or wire bonded to the support post.

All metallic doors permitting access to the building or structure shall be bonded to the ground ringelectrode.

Frames of roll-up or slatted doors shall be bonded to the ground ring electrode.Metallic barricades and bollards within the sideflash distance as calculated per

Section 4.21.2.4(A) shall be bonded to the ground ring electrode using a buried conductor.All railroad tracks that come within 1.9 m (6 ft) of an explosives facility shall be bonded to the

lightning protection system ground ring electrode as shown in Figure 8.5.12.

***Insert Figure 8.5.12 Grounding and Bonding of Railroad Tracks Here***

Where railroad tracks provide electrical signaling, insulated joints shall be provided to isolate railroad sidingtracks from the main railroad track.

Siding tracks shall provide external bonds for bonding to the facility’s ground ring electrode.Where railroad tracks enter a facility, they also shall be bonded to the frame of the structure or facility.



Lightning protection on earth covered magazines shall be installed as specified inChapter 4, except as modified below.

Air terminals shall be placed on the headwall, the rear ventilator (if present), and at the perimeter of themagazine roof as required to obtain a 100’ radius zone of protection.

***Insert Figure 8.6.1.1 Here***

Tall air terminals in the center of the magazine headwall and roof shall be permitted in lieu of perimeter airterminals only if they provide adequate protection in accordance with 8.2.1.

The steel doors, door frames, and steel reinforcement shall be bonded to the grounding system.Incoming power, data, and communication systems shall be bonded to the ground ring electrode or steel

reinforcement upon entering the structure.LPS shall be required on piers and wharves when explosive materials cannot be moved to

a protected area at the approach of a thunderstorm.The purpose of the LPS on the piers or wharves is to protect the explosives positioned on these structures

from being ignited by direct lightning strikes. A ship alongside is capable of providing a zone of protection for a sectionof a wharf or pier. The portion of the pier or wharf used for explosives staging will require lightning protection from amast or catenary system.

The portion of the pier or wharf used for explosive material staging shall be provided with a mast or catenarysystem.

The mast or catenary systems shall be interconnected with a ground ring conductor.An additional conductor shall be installed along the pier or wharf for bonding of all permanently installed metal

objects on the pier.All pier and wharf ground ring conductors shall be interconnected.A path to earth consisting of a metal plate bonded to this additional ground ring conductor shall be permitted to

create a low resistance path by submerging in water.All cranes shall be provided with inner and outer ground ring conductors interconnected with each other.

The crane shall be bonded to the inner ground ring conductor.Cranes shall be re-located into the lightning protection zone of protection at the approach of a thunderstorm.Boom and cable lifting shall be bonded to the outer ground ring conductor.

Metal lifting hooks on cranes equipped with hook insulating links shall not be required to be bonded to anyof the ground ring conductors.

Open storage pads shall be provided with a mast or catenary system.An additional ground ring conductor shall be installed where:

(1) Explosive materials are within sideflash distance of cables or masts(2) Flammable gases or exposed flammable liquids are present on the pad

Portable magazines that provide equivalent protection of a metallic cage asdescribed in 8.3.1 shall be grounded using main-size conductors.

Metal portable magazines of the box-type having 4.8 mm (0.19 in) steel or equivalent where the walls, floor,and roof are welded together shall require bonding of the doors across each hinge.

Power, data and communication systems shall be bonded to the structure at their respective service entrances.

Single portable magazines less than 2.323 m2 (25 ft2) (using outside dimensions) shall require a singleground rod.

Single portable magazines equal to or greater than 2.323 m2 (25 ft2) shall be grounded by using a minimumof two separate ground rods each placed in a different corner, preferably at opposing corners.

Connections to an existing ground ring electrode shall be permitted in lieu of ground rods.

Each group shall have a minimum of two connections to earth.Groups exceeding 76 m (250 ft.) in perimeter shall have a connection to earth for every 30.5 m (100 ft.) of

perimeter or fraction thereof, such that the average distance between all connections to earth does not exceed 30.5 m(100 ft.).

For small groups requiring only two connections to earth, the connections shall be placed at opposite ends ofthe group and as far apart as is practical.


Report on Proposals – June 2010 NFPA 780Connections to existing ground ring electrodes shall be permitted in lieu of ground rods.All earth connections shall provide as low as practical resistance to earth.

Surge protection as described in 4.18 shall be required for all power, communication, or dataconductors entering or exiting a structure housing explosives.

Power and metallic communication lines (including intrusion detection lines) shall enter the facility in shieldedcables or metallic conduit run underground for at least 50 feet from the structure.

Conduits shall be bonded to the ground ring electrode where they cross.Use of low-pass filters shall be permitted for added protection on critical electronic loads as determined by the

AHJ.A maintenance and inspection plan shall be developed for all protection systems

used to protect structures housing explosives.The effectiveness of any LPS depends on its installation, maintenance, and testing methods used.

Therefore, all installed LPS shall be properly maintained and inspected in accordance with this TP and the requirementsoutlined in DoD 6055.9-STD4 and NFPA 780. Proper records of maintenance and inspections shall be maintained oneach facility to ensure adequate safety. These records are part of the lightning protection requirements and shall bemaintained by the DoD Components.

The initial installation shall be inspected by the authority having jurisdiction and re-inspected and recertifiedfollowing any work done on the structure.

Maintenance guidelines of the LPS shall be provided at the completion of any LPS installation.Maintenance personnel shall ensure that repairs of all discrepancies found during inspections are made prior to

resuming explosives operations.Any indication of damage produced by a lightning strike to a structure or its LPS shall be immediately

documented and reported to the appropriate authority.Where allowed by the AHJ, photographic records of damage suspected to have resulted from a lightning strike

shall be obtained prior to repair.To prevent personnel shock, maintenance, inspection and testing shall not be conducted during threat of

thunderstorm.Lightning protection systems on explosives facilities shall be inspected visually at 6 month intervals for evidence

of corrosion or broken wires/connections.All necessary repairs shall be made immediately.Any detected damage to the system shall be entered in the test records.Lightning surge protection shall be inspected in accordance with manufacturer’s instruction at intervals not

exceeding 24 months or whenever electrical testing of the LPS is performed per 8.8.7.2.The lightning protection system shall be tested electrically every 12 months.

The instrument used in earth resistance testing should be capable of measuring 0 ohms to 50 ohms ± 10percent. The instrument used to measure bonding resistance should be capable of measuring 0 ohms to 10 ohms ±10percent.

The DC resistance of any single object bonded to the lightning protection system shall not exceed 1 ohm.The test shall be conducted in accordance with the appropriate test equipment manufacturer’s instructions.The test shall be conducted by personnel familiar with lightning protection system testing.Only those instruments designed specifically for earth resistance testing shall be permitted for use in this

application.Test instruments shall be properly maintained and calibrated in accordance with manufacturer’s instructions.The three-point fall-of-potential test method shall be used when measuring the resistance to earth of grounding

systems for explosives facilities.Surge suppressors shall be verified operable every 12 months or after any suspected lightning strike.Records and test measurement data of resistance to earth and bonding tests shall be documented and shall

be available for a time period acceptable to the AHJ.Only qualified personnel having the necessary training and expertise shall be permitted to maintain, inspect

and test explosives facilities.Assistance in determining a qualified person can be found in NFPA 70E Standard for “Electrical Safety in

the Workplace.”This proposal was developed by the NFPA 780 Explosives TG committee members to move Annex K

into the normative portion of the document.


Report on Proposals – June 2010 NFPA 780Relocate existing Chapter 8, Protection for Watercraft to Chapter 9.New Chapter 9 to read as follows:

**** INCLUDE 780_L89_CA.doc HERE****

****Insert Fig 780_L89_R 9_3_2_2_2.jpg HERE ****

****Insert Fig 780_L89_R 9_5_8.jpg HERE****The TC edits the submitter's text. The change meets the submitter's intent.

Affirmative: 23 Abstain: 15 Batchelor, C., Rakov, V., Reehl, D., Rison, W., Strother, L.

DALEY, R.: Annex A should note that DOD recommends 25 ohm resistance to ground for system.Referenced drawings not shown.



_______________________________________________________________________________________________

Mitchell A. Guthrie, Independent Engineering ConsultantRevise text to read as follows:

"A.8.1.3 Annex L can be used as a guide in quantifying the level of risk associated with the level of protection providedin the application."Add the following revision to Annex L to provide the level of assessment required for this application:"L.1 General. This Lightning Risk Assessment methodology is provided to assist the building owner, safety

professional, or architect/engineer in determining the risk of damage due to lightning. This annex provides a simplified,quick-look risk assessment (Annex L.5) and a more detailed assessment for those requiring a more detailed analysis(Annex L.6). Once the risk has been determined, the development of protection measures can begin. The methodologyconsiders only the damage caused by a direct strike to the building of structure to be protected and the currents flowingthrough the lightning protection system.L.1.1 There are some cases where the need for protection should be given serious consideration regardless of the

outcome of the risk assessment. Examples are those applications where the following are factors:(1) Large crowds(2) Continuity of critical services(3) High lightning flash frequency(4) Tall isolated structure(5) Building containing explosive or flammable materials(6) Building containing irreplaceable cultural heritage"Delete L.1.2 and Table L.1.2Renumber existing L.1.3 through L.1.5 as L.1.2 through L.1.4.L.2 through L.4 remains unchanged.Change title of L.5 from "Tolerable Lightning Frequency" to "Simplified Risk Assessment" and revise the text as

follows:"L.5 Simplified Risk Assessment.L.5.1 General. The methodology for a simplified risk assessment is described in this section. The objective is to

calculate the tolerable lightning frequency (Nc) and compare it to the expected lightning strike frequency as calculatedaccording to Clause L.3. The tolerable lightning frequency (Nc) is a measure of the risk of damage to the structureincluding factors affecting risks to the structure, environment, and monetary loss. It is calculated by dividing theacceptable frequency of property losses by various coefficients relating to the structure, the contents, and theconsequence of damage. The acceptable frequency of property losses may be set by the authority having jurisdiction ora default value of 1.5 × 10-3 may be used. The coefficient value (C) used in the denominator is the product of thecomponent coefficients where C = (C2)(C3)(C4)(C5). The values of C2 through C5 are obtained from Table L.5.1(a)through Table L.5.1(d)"Renumber Tables L.5(a), Table L.5(b), Table L.5(c), and Table L.5(d) as Table L.5.1(a), Table L.5.1(b), Table L.5.1(c),

and Table L.5.1(d).Renumber L.6 as L.5.2 and rename "Risk Calculation."Renumber L.6.1, L.6.2, L.6.3, and L.6.4 as L.5.2.1, L.5.2.2, L.5.2.3, and L.5.2.4. Change title of Table L.6.4 to: "Table

L.5.2.4 Determination of Protection System Requirement"Change L.6.4 to read as follows:"L.5.2.4 Table L.5.2.4 provides a simple method of calculating and using the simplified assessment methods described

in Annex L.5."Add new L.6 as follows:" L.6 Detailed Assessment.L.6.1 Introduction. The methodology described in this clause involves the calculation of the risk of losses due lightning

with the tolerable level of risk. The procedure involves the comparison of the evaluated risk to the tolerable oracceptable risk to a structure. These assessments will provide a risk for lightning discharges to cause a loss of humanlife (or living beings), a loss of cultural heritage, and economic losses. Providing three risk factors will allow a facilityowner or manager to make an informed decision as to the benefits of providing lightning protection for the structurebased on a more diverse set of factors.


Report on Proposals – June 2010 NFPA 780L.6.2 Values of Tolerable Risk, R. Values of tolerable levels of loss may be selected by the authority having jurisdiction.

Some default values that may be used where levels are not provided by the authority having jurisdiction are given inTable L.6.3.

Table L.6.3Typical Values of Tolerable RiskType of Loss RT/yr

Loss of human life or injury 10-5

Loss of service to the public 10-3

Loss of cultural heritage 10-3

L.6.3 Types of Risk Due to Lightning. The types of risk due to lightning for a particular structure or facility may includeone or more of the following:(a) R1 - risk of loss of human life or injury(b) R2 - risk of loss of service to the public(c) R3 - risk of loss of cultural heritage(d) R4 - risk of loss of economic valueThese risk categories are composed of risk components that are summed to determine the overall risk of the loss in a

given application. The risk components are characterized according to the type of loss and source of the threat. Threatsto be considered in the assessment are associated with:- flashes to the structure- flashes to a service entering a structure- flashes near a service, and- flashes near a structureL.6.4 Risk Components. Relevant risk components to be considered in the assessment of the risk of the losses

identified in L.6.3 are identified in 6.4.1 through 6.4.4. They are categorized according to the cause of the damage.L.6.4.1 Lightning strikes directly to a structure- RA - injury to humans due to flashes to a structure (touch and step potentials)- RB - damage to structure due to direct strike to a structure- RC - failure of internal systems due to flashes to a structureL.6.4.2 Flashes to a connected service- RU - injury to humans due to flashes to connected service- RV - damage to structure due to flashes to connected service- RW - failure of internal systems due to flashes to connected serviceL.6.4.3 Flashes near a connected service- RZ - failure of internal systems due to flashes near a serviceL.6.4.4 Flashes near a structure- RM - failure of internal systems due to flashes near a structureL.6.5 Calculation of Risk. Each component of risk Rx depends on the number of dangerous events Nx (strikes in the

area of interest), the probability of damage Px (or shock to living beings), and the expected loss related to the event Lx.The value of each component of risk Rx may be calculated using the following expression:

Rx = Nx × Px × Lx

where:Nx = average number of lightning strikes affecting the structure or servicePx = probability of damageLx = loss factorL.6.6 Procedure for Risk Assessment and Management. The procedure for the risk assessment is to first identify the

structure or facility to be evaluated. This involves defining the extent of the facility or structure being assessed. Thestructure or facility will be a standalone structure in most cases. The structure may encompass a building and itsassociated outbuildings or equipment support structures. One must then determine all relevant physical, environmental,and service installation factors applicable to the structure.The second step is to identify all the types of loss relevant to the structure or facility. For most structures, only R1 and

R3 may need to be considered. R2 will apply to museums, galleries, libraries, churches, and heritage listed buildings. Foreach type of loss relevant to the structure, choose the relevant loss factors.


Report on Proposals – June 2010 NFPA 780Next, determine the maximum tolerable risk (RT) for each relevant type of loss for the structure by identifying the

components (Rx) that make up the risk, calculate the identified components of risk, and calculate the total risk due tolightning (R).Compare the total risk (R) with the maximum tolerable risk (RT) for each type of loss relevant to the structure. If R < RT

for each type of loss relevant to the structure than lightning protection may not be needed."The proposed text of 8.1.3 correctly cautions that the protection detailed in the chapter reduces but

does not eliminate the risk to watercraft and its occupants; but it does not provide information as to how one coulddetermine the overall risk. This proposal attempts to provide guidance to the user in determining the risk and provides aproposed revision to Annex L to provide a sufficient level of assessment adequate to cover the application.



TOBIAS, J.: Thanks to the Dr. Covino & the explosives structures task group for realizing this new chapter in thenormative section. Well done!

_______________________________________________________________________________________________780-70 Log #72


Revise text to read as follows:

The paragraphs following this title have nothing to do with dissimilar metals, and simply describe thepermitted materials. Hence, the wording change.


_______________________________________________________________________________________________780-71 Log #33


Revise text to read as follows:8.2.2.4* Carbon fiber composite (CFC) shall not be used as a conductor in a lightning protection system.

Carbon fiber composite (CFC) is not permitted toshall not be used as a conductor in a lightning protectionsystem.

Task group made changes add mandatory text. Relocating non mandatory text to the annex.





Revise text to read as follows:Strike termination devices shall meet the requirements of Section 4.6 and Table 4.1.1.1(A) and shall be so located and

high enough so as to provide a zone of protection that covers the entire watercraft.Revised for clarity, grammar, and streamlining.


_______________________________________________________________________________________________780-73 Log #6

_______________________________________________________________________________________________Eduardo Mariani, CIMA Ingenieria SRL

Revise text as follows:Cp= specific heat capacity in J kg-2 K-1 J kg-1 K-1

The specific heat capacity is defined for the unit of mass. [gram, Kg, mole, etc]. Kg-2 is a misspelling.


_______________________________________________________________________________________________780-74 Log #36


Eliminate hyphen from main-size in the following sections: 8.4.3.1.Committee changes made to delete the Hyphen in order to establish consistency as per the manual of

style.





Revise text as follows:8.4.5.2 When a joint is made between conductors of the same material, the contact area shall be at least as large as

the cross sectional area of the conductor.8.4.5.2.1 Depending on the material, the contact minimum area for a joint in a main conductor shall be given by 8.4.1.1

(for copper), 8.4.1.2 (for aluminum), or 8.4.1.3 (for other metals).8.4.5.2.2 For a joint in a bonding conductor, or between a bonding conductor and main conductor, the contact

minimum area shall be given by 8.4.2.1 (for copper), 8.4.2.2 (for aluminum), or 8.4.2.3 (for other metals).When a joint is made between conductors of the same material, the contact area shall be at least as large as

the cross-sectionalcross sectional area of the conductor.8.4.5.2.1 Depending on the material, the contact minimum area for a joint in a main conductor shall be given by

8.4.1.1 (for copper), 8.4.1.2 (for aluminum), or 8.4.1.3 (for other metals).8.4.5.2.2 For a joint in a bonding conductor, or between a bonding conductor and main conductor, the contact

minimum area shall be given by 8.4.2.1 (for copper), 8.4.2.2 (for aluminum), or 8.4.2.3 (for other metals).Task group made changes to comply with MOS 1.8.3.


_______________________________________________________________________________________________780-76 Log #2

_______________________________________________________________________________________________Ewen Thomson, Marine Lightning Protectin Inc.

Add text as follows:8.5.3.4 A main grounding electrode may comprise multiple immersed solid conductors that are interconnected by at

least one main conductor where each conductor satisfies Section 8.5.3.3 and the aggregate contact area as determinedby Section 8.5.3. is at least 0.09 m2 (1.0 ft2).

A.8.5.2.1 recommends that grounding electrodes should be mounted as close to the waterline aspossible. If a total immersed area of 1.0 ft2 is required as a minimum, it is more effective to divide this amongst multipleconductors that can then be mounted further outboard and located to promote symmetrical current flow towards thewaterline. This minimizes current flow, and hence step voltages, beneath the watercraft. Otherwise, if only one is usedits placement is limited to the bow or the stern if it is to be close to the waterline. Alternatively, it is likely to be placedamidships, thereby maximizing step voltages, or to one side of a keel, thereby promoting asymmetrical current flow.

8.5.3.4 to read as follows:8.5.3.4 A main grounding electrode shall be permitted to be comprised of multiple immersed solid conductors that are

interconnected by at least one main conductor where each conductor satisfies 8.5.3.3 and the aggregate contact areaas determined by 8.5.3. is at least 0.09 m2 (1.0 ft2).

The TC edits the submitter's text as it was not in mandatory language.The change meets the submitter's intent.




_______________________________________________________________________________________________Carl S. Johnson, II, AVCON, Inc.

Please see the document I have included that provides language for a proposed new Chapter 9 toaddress lightning protection for airfield lighting systems.

***** See Include 780_L3_R***** - The Include contains 3 pieces of artwork***

NFPA 780 does not address lightning protection for airfield lighting circuits. The new proposedChapter 9 provides lightning protection criteria for airfield lighting systems. Please see Part 5 for research paper andreference list that I have provided.Note: Supporting material is available for review at NFPA Headquarters.

The TC sees this as bonding and grounding issues rather than lightning protection issues.The proposal is beyond the scope of NFPA 780. The submitter is referred to 1.1.1.There are 4 different standards that currently exist on this subject. The TC believes it would be improper to address

this subject without coordination with other organizations such as FAA, NAVAIR, and Air Force program offices.


GUTHRIE, M.: I do not agree with the committee statement that the hazard identified is not a lightning protectionproblem. It is the lightning threat that results in the grounding problem addressed.



_______________________________________________________________________________________________Matthew Caie, ERICO, Inc.

Add new text to read as follows:

The intent of this chapter shall be to provide lightning protection requirements for wind turbines,specifically wind turbine structures that comprise externally rotating blades, a nacelle, and supporting tower.

Lightning protection systems installed on wind turbines shall be installed in accordance with the provisions of thischapter.

This chapter does not include the lightning protection of the wind turbine blades. This protection is addressed byspecific manufacturer product approval standards.

Placement of air terminations for the nacelle, shall be determined as described in section 4.7, assuming theblades are oriented so they provide the smallest zone of protection to the structure.

The nacelle, hub and other structural components of the wind turbine shall be substituted for air terminals andconductors where possible in accordance with section 4.6.1.3 and 4.16.

Air terminations, down conductors and bonding for the protection of meteorological instruments and aircraftwarning lights located on the nacelle, shall be provided in accordance with the Chapter 4.

The blade to hub transition conductor shall be sized in accordance with table 4.1.1.1 (B) for main conductors andprovided with a minimum required allowance and flexibility for adequate motion of the blade.

The cover for the hub, referred to as the spinner shall be protected with a strike termination device as required inSection 4.6.

t least two down conductors shall be provided for the tower of the wind turbine. The down conductorrequirements from the nacelle to ground shall be provided in accordance with Section 4.9.9.

Metal bodies located outside or inside the wind turbine structure that contribute to lightning hazards because theyare grounded or assist in providing a path to ground for lightning current shall be bonded to the overall lightningprotection system in accordance with Sections 4.19, 4.20, and 4.21.

The nacelle, hub, tower and base structure sections ofthe wind turbine typically house electrical and mechanical control systems, consideration shall be given to the protectionof these systems with bonding, shielding and surge protection in accordance with section 9.3

Maintain separation distance and bonding techniques in accordance with Sections 4.20 and 4.21.Maximise the distance between lightning conductors and electrical system components, locate electrical system

cabling on or near a ground plane.Electrical system cabling shall be magnetically shielded by either braided wire sheath or wire mesh screen or

bonding of metallic conduit, cable trays or raceways.Locate electrical equipment that is exposed to lightning electromagnetic impulse (LEMP) within metal enclosures.Avoid large loop areas within electrical cabling.SPDs shall be installed as close as practicable to the equipment to be protected. SPDs shall be in accordance

with section 4.18.Each wind turbine structure shall be equipped with a common grounding system in accordance with

Section 4.14, and interconnect to the site grounding system, if present.The lightning protection grounding system shall be in accordance with 4.13.1 through 4.13.8, consideration shall

be given to design requirements for power generation facility grounding, including sizing of conductors for fault currentsand touch and step potential requirements.

The grounding system for a wind turbine shall comprise a ground ring electrode and ground rods located externalto the wind turbine foundation, in contact with the soil and bonded to the foundation reinforced concrete using fittingslisted for the purpose.

Electrical continuity of steelwork in reinforced concrete structures must be ensured. Steelwork within reinforcedconcrete structures are considered to be electrically continuous if the major parts of vertical and horizontal bars areconnected.

Free standing structures located adjacent to the base of the wind turbine shall be bonded to the ground electrodesystem of the main structure in accordance with Section 4.14.1.4.


Report on Proposals – June 2010 NFPA 780Closed metallic grid-like or continuous screen enveloping the object to be protected, or part of it, used to reduce failuresof electrical and electronic systems.

Electromagnetic effects of lightning current, which includes conducted surges as well as radiated impulseelectromagnetic field effects.

Provide guidance to the application of lightning protection to wind turbine structures. Presently nospecific guidance is provided within the NFPA 780 document.

Relocate existing Chapter 8, Protection for Watercraft to Chapter 10.Delete 5.8.Delete Annex N.New Chapter 10 to read as follows:

****INCLUDE 780_L87_CA .doc HERE****

The TC edits the submitter's text. The change meets the submitter's intent.


MCAFEE, D.: This should be new Chapter 9, not Chapter 10 as stated in the Report on Proposals.TOBIAS, J.: Thanks to Mr. Caie & the Wind Turbine task group for bringing this to the normative section. Well done!VANSICKLE, III, H.: Par. 10.2.3 - remove the word "the" before Chapter 4 at the end of the sentence.

Par. 10.4.1 & 10.4.2 seem to require 2 different approaches, one called "lightning protection grounding" which could beby various means including a plate or radial and the other called "the grounding system" which must be a ground ringwith ground rods. This is confusing.Par. 10.4.3 & 10.4.4 outlines the need for continuity during construction of the rebar, but lacks a reference to 4.10.13which necessitates bonding the down conductors to the reinforcing steel top and bottom of each run.3.3.b defines "Magnetic Shield", but I don't see this specific term used. Par. 10.3 (C) discusses "magnetically shielded".Is this the proper reference?



_______________________________________________________________________________________________Bob Eugene, Underwriters Laboratories Inc.

Revise text as follows:A.3.3.27 Suppressed Voltage Rating (SVR). The SVR is a rating (or ratings) selected by the manufacturer based on

the measured limiting voltage determined during the transient voltage surge suppression test specified in UL 1449, ULStandard for Safety Transient Voltage Surge Suppressors, 2nd Edition. This rating is the maximum voltage developedwhen the SPD is exposed to a 6KV/500 A, 1.2x50 us, 8/20 us current limited combination waveform through the device.It is a specific measured limiting voltage rating assigned to a TVSS by testing done in accordance with UL 1449.Nominal SVR values include 330 V, 400 V, 500 V, 600 V, 700 V, and so forth.Devices rated in accordance with ANSI/UL 1449, UL Standard for Safety Transient Voltage Surge Suppressors

Protective Devices, Edition 3, will reflect a Voltage Protection Rating (VPR) in place of the SVR. This is to reflect thedifference that the voltage protection rating test will utilize a 3 kA peak current instead of the 500 A current level used inthe SVR test of UL 1449, Edition 2.

The ANSI designation should be added to UL 1449, Third Edition to reflect the ANSI approval of thereferenced standard. Additional editorial changes reflect the differences between the 2nd and 3rd editions of thestandard.







Revise text as follows:The SVR VPR is a rating (or ratings) selected by the manufacturer

based on the measured limiting voltage determined during the transient voltage surge suppression test specified in UL1449, . This rating is the maximumvoltage developed when the SPD is exposed to a 500 3 kA, 8/20 ìs current limited waveform through the device. It is aspecific measured limiting voltage rating assigned to a TVSS an SPD by testing done in accordance with UL 1449,Edition 3. Nominal SVR VPR values include 330 V, 400 V, 500 V, 600 V, 700 V, and so forth.

To reflect the changes made to UL 1449, Edition 3.

Delete * following 3.3.27.Add * following 3.3.35.A.3.3.35 to read as follows:A.3.3.35 Voltage Protection Rating (VPR). The SVR VPR is a rating (or ratings) selected by the manufacturer based on

the measured limiting voltage determined during the transient voltage surge suppression test specified in UL 1449,. This rating is the maximum voltage

developed when the SPD is exposed to a 500 3 kA, 8/20 ìs current limited waveform through the device. It is a specificmeasured limiting voltage rating assigned to a TVSS an SPD by testing done in accordance with UL 1449, Edition 3.Nominal SVR VPR values include 330 V, 400 V, 500 V, 600 V, 700 V, and so forth.

The TC changes A.3.3.27 to A.3.3.35 (add * following A.3.3.35) and changes the title of UL1449.






A.4.7.3.1 to be changed to A.4.7.4.1 and read as follows:43 Figure 4.7.43.3 depicts the 46 m (150 ft) rolling sphere method for structures of selected heights up to 46

m (150 ft). Based on the height of the strike termination device for a protected structure being 7.6 m (25 ft), 15 m (50 ft),23 m (75 ft), 30 m (100 ft), or 46 m (150 ft) above ground, reference to the appropriate curve shows the anticipated zoneof protection for objects and roofs at lower elevations.

The graph shows the protected distance ("horizontal distance") as measured radially from the protected structure.The horizontal distance thus determined shall apply only at the horizontal plane of the "height protected."

Committee changes made to address the issue of no mandatory text.



_______________________________________________________________________________________________780-82 Log #22


Renumber Annex A.4.13.2.4 to A.4.13.2.2Minimal benefit is gained from the second ground rod if placed closer than the sum of the driven depth of

both rods.Task group made changes to comply with MOS1.8.3.2



_______________________________________________________________________________________________780-83 Log #74


Revise text to read as follows:Radial aAugmentation of the grounding system specified in 4.13.5 and 4.13.8.2 by the use of one or more

radial conductors is recommended. Radial conductors should be sized in accordance with the requirements for mainconductors and installed in accordance with 4.13.8.1.

Word deleted because radials are not mentioned in 4.13.8.2.





Change A.4.18.1* to read as follows:A.4.18.1 General. This section provides requirements for surge protection systems installed for the electrical,

communications (including but not limited to CATV, alarm, and data) or antenna systems, or other electrical systemhardware. Surge protection alone is not intended to prevent or limit physical damage from a direct lightning strike to afacility or structure. Rather, it is intended to defend against indirect lightning effects imposed upon the electrical servicesto a structure as part of a coordinated lightning protection system installed in accordance with the requirements of thisstandard. Surge currents and their corresponding overvoltage transients can be coupled onto electrical utility feeders ina number of ways. These mechanisms include magnetic or capacitive coupling of a nearby strike or the more dramaticbut much less frequent conductive coupling of a direct cloud-to-ground discharge. These overvoltage transients pose asignificant threat to modern electrical and electronic equipment.

Task group made changes add mandatory text. Relocating nonmandatory text to the annex.







Revise text as follows:SPDs are typically sized significantly larger than the expected challenge level. At service entries, it is

generally agreed that a maximum nominal discharge current (In)between 40 kA and 60 of 20 kA will provideadequate protection. However, larger ratings that protect against less probable, but more powerful lightning events, willusually provide a better capability to handle multiple strikes and will usually provide a longer service life.Rating the SPD’s higher than the minimums in this document is recommended in areas with frequent lightning.Where installed, SPDs at branch panels or subpanels should have an rating of 210 kA 8/20 ìs or greater per

phase.Where installed, supplementary protection (also called point of utilization) SPDs should have an rating of 10 5

kA 8/20 ìs or greater per phase.To reflect the changes made in UL 1449. Edition 3.



_______________________________________________________________________________________________780-86 Log #54


Revise text as follows:The measured limiting voltages of the SPD should be selected to limit damage to the service or equipment

protected. Devices rated in accordance with UL 1449,Protective Devices., Edition 3, will reflects a VPR in place of the SVR. This is to reflect that the voltage rating test inEdition 3 will utilizes a 3 kA peak current instead of the 500 A current level used in the SVR test of UL 1449, Edition 2.

To reflect the incorporation of UL 1449, Edition 3.






Add new text as follows:A.4.18.6.1 SPDs should be placed on both ends of external signal, data, and communication lines longer than 30 m

(100 ft) connecting pieces of equipment or facilities, to protect against surges coupled into the wiring or caused byground potential differences.

To supplement the proposal to add discussion on need for additional protection for specialapplications.

NFPA 780-2008 already has this identical text.


_______________________________________________________________________________________________780-88 Log #55


Revise text as follows:Some SPD units are provided with a failure indicator. This feature is recommended since it facilitates

maintenance or test procedures. Where used, this indicator should be visible. Building maintenance should considerperiodic inspection or test of SPDs (see NFPA 70B – Recommended Practice for Electrical Equipment Maintenance).

To incorporate reference to NFPA 70B.

Add to Annex O.1.1 in alphabetical order to read as follows:NFPA 70B , 2006 Edition

The TC accepts the submitter's text. The TC adds reference to 70B in Annex O.1.1.






Revise text as follows:The ability of the SPD earth ground resistance is part of by the total impedance of the SPD path to ground

circuit. The ability of the SPD to discharge current to ground is affected by this impedance.Also, a lower ground resistance minimizes voltage differences of conductors attached to SPDs near the service

entrance and reduces the chance of arcing or insulation breach. Consequently, it is essential to minimize impedance inthis circuit.

Editorial.

A.4.18.8 to read as follows:The effectiveness of the SPD is based on the impedance of the path to ground.

A lower ground resistance minimizes voltage differences of conductors attached to SPDs near the service entranceand reduces the chance of arcing or insulation breach. Consequently, it is essential to minimize impedance in thiscircuit.

The TC edits the submitter's text for clarity.The submitter's concern has been addressed by the text change.






Revise text as follows:In the structures covered in Chapter 7, a spark that would otherwise cause little or no damage might

ignite the flammable contents and result in a fire or explosion.Flammable vapors can emanate from a flammable liquid [flash point below 37.8°C (100°F)] or a combustible liquid

[flash point at or above 37.8°C (100°F)] when the temperature of the liquid is at or above its flash point. Chapter 7applies to these liquids when they are stored at atmospheric pressure and ambient temperature. Provided that thetemperature of the liquid remains below the flash point, combustible liquids stored under these conditions will notnormally release significant vapors since their flash point is defined to be at or above 37.8°C (100°F). Metallic tanks,vessels, and process equipment that contain flammable or combustible liquids or flammable gases under pressurenormally do not require lightning protection since this equipment is well shielded from lightning strikes. Equipment of thistype is normally well grounded and is thick enough not to be punctured by a direct strike. This chapter applies toflammable or combustible liquids such a gasoline, diesel, jet fuel, fuel oil, or crude oil stored at atmospheric pressure. Itdoes not apply to liquids or gases stored under pressure, such as liquefied natural gases or liquefied petroleum gases.

Task group made changes add mandatory text. Relocating non mandatory text to the annex.



_______________________________________________________________________________________________780-91 Log #45


Revise Figure F.1 tree trunk/root/electrode detail as follows.Show the radial electrode arms at regular intervals around the entire tree trunk and interconnected at their tree trunkend. Delete the (apparent) main conductor leading from the splicer to (apparently) Figure F.1 Item (7).

These changes will then have Figure F.1 matching the present text in Section F.2.5(1) which indicatesthat either the radial arm electrode system can be employed or the single driven rod installed.The radial arm electrodes can be divergent at any appropriate spacing, with the end result having the electrode systemmimic a disk of the same radius because of the overlapping mutual spheres of each radial arm.

As this is Annex material, the figure does not provide requirements and is not intended to be aliteral representation of the text.





Revise text to read as follows:Design concerns for lightning protection systems on open shelters include the following:

(1) Step potential(2) Touch potential(3) Sideflash to persons and animalsLightning protection systems for open shelters should conform to the requirements of Chapters 4 and 5 with the

guidance given in G.1.1.1 through G.1.1.3.There’s no reason that shelters can’t be protected according to Chapter 4, if they’re more like actual

structures.

G.1.1 to read as follows:G.1.1 Design concerns for lightning protection systems on open shelters include the following:(1) Step potential(2) Touch potential(3) Sideflash to persons and animalsLightning protection systems for open shelters should conform to the requirements of Chapter 4 with the guidance

given in G.1.1.1 through G.1.1.3.The TC notes that the correct reference is to Chapter 4 and not to Chapter 5.




_______________________________________________________________________________________________David E. McAfee, Fire and Lightning Consultants

Completely replace the existing Annex L with the proposed new Annex MaterialReplace Figures L.2 (a) with the new figure attached.Replace Figure L.2 (b) with attached figure attached.

***Include 780_L90_R here***

The existing Annex L material is being replaced with revised text and material to update themethodology to more closely adhere to the methodology provided by the IEC. The new text revises the existingmethodology to update it and change it to a Simplified Risk Assessment. The new material also provides a new DetailedRisk Assessment methodology that includes additional risk and loss factors that more closely resemble methods used ininternational Lightning Codes and Standards.

INCLUDE 780_L90_CA.doc HERE

INCLUDE 780_L90_R L_2.pdf HERE

INCLUDE 780_L90_R L_4_1_1.pdf HERE

INCLUDE 780_L90_R L_4_1_2_a.pdf HERE

INCLUDE 780_L90_R L_4_1_2_b.pdf HEREThe TC edits the submitter's text for clarity. The change meets the submitter's intent.


TOBIAS, J.: This significant and useful revision is due to the efforts of Mr. McAfee & the Risk Assessment taskgroup. Thanks and well done!



_______________________________________________________________________________________________Todd W McGibney, Law Office of Marc E. Mandel, LLC

Revise text to read as follows:Annex MGuide for Personal Safety from LightningM.2.3(5) Swimming Pools (Indoor or outdoor), lakes and seashoreM.3.3 No one should be in the water during a lightning storm. However, an indoor pool that is properly grounded in

accordance with this and NFPA 70 and properly maintained greatly reduces the risk of injury to swimmers usingthe indoor pool during a thunderstorm. This should not be construed to prevent swimmers from using an indoorpool during a thunderstorm.

During inclement weather, many indoor pools operate under the recommendation that swimmers mustexit the pool and remain out of the pool for a full 30 minutes from the last report of lightning or thunder. As a result, theswimmer's recreation or therapeutic time in the pool is disrupted. This need not be the case, because there is virtuallyno risk of injury to an individual who is swimming in a properly grounded building pursuant to the National Electric Code(NFPA 70). In the event that lightning strikes a properly grounded building containing an indoor pool, the charge shouldbe carried away from the body of water and not pose danger to the swimmers. In fact, there has not been any recordeddeaths to persons in indoor pools from lightning. Richard Kithil & Kevin Johnston,

http://www.lightningsafety.com/nlsi pls/indoor_pools.html (accessed Nov. 1, 2008).Note: Cross reference proposal for NFPA 70 regarding indoor pools sent on Nov. 5, 2008.

The submitter has not provided adequate technical substantiation and the change wouldpossibly reduce the margin of safety.





Revise text to read as follows:

The purpose of this annex is to furnish a guide for personal safety from lightning. Persons can be at riskprior to any visual or audible indication of a thunderstorm. Any time conditions exist that could lead to lightning activity,personal safety should be considered. Lightning warning systems are available to provide early warning of lightningactivity.

Most lightning strike victims are struck before or after the rain that usually accompanies thunder storms. Thiswould indicate that most people have the good sense to get out of the rain, but are not as conscious of the lifethreatening hazards presented by lightning. Atmospheric conditions that cause lightning can be measured and theprobability of a lightning event predicted. However, it is not possible to predict the exact location where lightning willstrike since it has been known to attach to earth beyond the visible horizon.Lightning is extremely dangerous and unnecessary exposure should be avoided.(1) When possible, plan outdoor activities around the weather forecast. Although it is difficult to know exactly if a

storm will occur, the conditions that create lightning storms such as the meeting of high and low pressure systems arepredicted days in advance. On days when such weather patterns are forecast, avoid planning activities where shelter isnot readily available such as boating or camping.(2) Check the forecast the night before and the morning of planned outdoor activities to see if lightning is a possibility.(3) Check internet website weather maps before you leave. Most weather sites have recent satellite and radar images

of the area of your activity.(4) When you arrive at the area of your activity, devise a plan on where to go in the event of an approaching Lightning

Storm. Tell all persons in your party, especially children, where to go in accordance with section M.2.2. Also, tell yourparty where you will meet a half hour after thunder is last heard, since you may not be together when the threat of astorm arises.(5) Carry a weather radio with an Alert feature to receive severe weather warnings. Respond accordingly when

warnings are issued.If you hear thunder, seek shelter immediately. Do not try to predict how close lightning is by counting the time

between the flash of lightning and the sound of thunder. Stay indoors until one half hour after you last heard thunder.Seek shelter in structures such as the following:(1) Dwellings or other buildings that are protected against lightning(2) Underground shelters such as subways, tunnels, and caves(3) Large metal-frame buildings(4) Large unprotected buildings(5) Enclosed automobiles, buses, and other vehicles with metal tops and bodies(6) Enclosed metal trains and street cars(7) Enclosed metal boats or ships(8) Boats that are protected against lightning(9) City streets shielded by nearby buildingsIf caught in a Lightning Storm with no shelter available, the following rules should be observed when a location can be

selected:(Insert sections to be former M.2.5(1),(2),(4) delete (3) completely)

Do not go out of doors or remain out, unless it is necessary. Seek shelter in structures such as the following:(1) Dwellings or other buildings that are protected against lightning(2) Underground shelters such as subways, tunnels, and eaves(3) Large metal frame buildings(4) Large unprotected buildings(5) Enclosed automobiles, buses, and other vehicles with metal tops and bodies(6) Enclosed metal trains and street cars(7) Enclosed metal boats or ships(8) Boats that are protected against lightning


Report on Proposals – June 2010 NFPA 780(9) City streets shielded by nearby buildings

If possible, avoid places with little or no protection from lightning such as the following:(1) Small, unprotected buildings, barns, sheds, and so forth(2) Tents and temporary shelters(3) Automobiles (nonmetal top or open)(4) Trailers (nonmetal or open)

Certain locations are extremely hazardous during thunderstorms and should be avoided if at all possible.Approaching thunderstorms should be anticipated and the following locations avoided when thunderstorms are in theimmediate vicinity:(1) Hilltops and ridges(2) Areas on top of buildings(3) Open fields, athletic fields, golf courses(4) Parking lots and tennis courts(5) Swimming pools (indoor or outdoor), lakes, and seashores(6) Near wire fences, clotheslines, overhead wires, and railroad tracks(7) Under isolated trees(8) Near electrical appliances, telephones, plumbing fixtures, and metal or electrically conductive objects

It is especially hazardous to be riding in or on any of the following during thunderstorms while in the locationsdescribed in M.2.3:(1) Open tractors or other farm machinery operated in open fields(2) Golf carts, scooters, bicycles, or motorcycles(3) Open boats (without masts) and hovercraft(4) Automobiles (nonmetal top or open)

If caught in a Lightning Storm with no shelter available, the following rules should be observed when a locationcan be selected:it is not always possible to choose a location that offers good protection from lightning, but the following rules should be

observed when a location can be selected:(1) Seek depressed areas -- avoid mountaintops, hilltops, and other high places.(2) Seek dense woods -- avoid isolated trees.(3) Seek buildings, tents, and shelters in low areas -- avoid unprotected buildings.(43) If caught in an exposed area, crouch as low as possible, kneel on the ground, keeping feet together, pPutting

your hands on your thighs knees. Do not place your hands on the ground. To minimize risk of direct strike, it isnecessary to keep as low as possible. To minimize risk of step potential hazards, it is necessary to minimize the area ofthe body in contact with the ground. Do not lie flat.

Inasmuch as the basic purpose of protection against lightning is toensure the safety of persons, it is appropriate that the precautions and suggestions in M.3.1 through M.3.3 be listed inaddition to all applicable recommendations in the preceding sections.

One should remain inside a closed boat, as far as practical, during a lightning storm and should not danglearms or legs in the water.

To the extent consistent with safe handling and navigation of the boat during a lightning storm, one shouldavoid making contact with any items connected to a lightning protection system, especially in such a way as to bridgebetween these items. For example, it is undesirable for an operator to be in contact with reversing gear levers andspotlight control handle at the same time.

No one should be in the water during a lightning storm.

Lightning Conditions are to be monitored continuously. In most cases, a combination of a lightning networksubscription service, a professional grade lightning warning system, and a high quality hand held detector is suggested.However, if thunder is heard, the danger from lightning is close enough to suspend operations and seek refuge.

Suspension and resumption of work activities are planned in advance, through policies and training.Information can be transmitted by some or all of the following methods:

(1) Sirens(2) Strobe lights(3) Text messages(4) 2-way radios(5) Telephone


Report on Proposals – June 2010 NFPA 780Yellow condition: Lightning is in the 20-40 mile (30-60 km) range and the threat may exist.Amber condition: Lightning is in the 10-20 mile (16-30 km) range and the threat is nearby.Red Alert: Lightning is in the 0-10 mile (0-16 km) range and no personnel are allowed outdoors. All outside personnel

must seek safety in a designated shelter that is equipped with a lightning protection system that complies with thisstandard. If not available, seek shelter in the structures listed above in M.2.2.

Wait until one-half hour after thunder is no longer heard before resuming outdoor activities. Be extra cautiousduring this storm phase as lightning still may be a significant hazard.

Organizations should create, publish and train personnel on appropriate lightning safety guidelines, inaccordance with the recommendations above.

Individuals that have been struck by lightning do not carry an electrical charge and are safe to assist.Administer first aid and/or CPR immediately, if qualified. Get emergency help immediately.

Committee changes made to reflect changes in technologies, understanding and recommendedpractices

Revise text to read as follows:Annex M Guide for Personal Safety from Lightning

M.1 Scope. The purpose of this annex is to furnish a guide for personal safety from lightning. Persons can be at riskprior to any visual or audible indication of a thunderstorm. Any time conditions exist that could lead to lightning activity,personal safety should be considered. Lightning warning systems are available to provide early warning of lightningactivity.M.2 Personal Conduct During Concerning Lightning Activity.M.2.1 Most lightning strike victims are struck before or after the rain that usually accompanies thunder storms. This

would indicate that most people have the good sense to get out of the rain, but are not as conscious of the lifethreatening hazards presented by lightning. Atmospheric conditions that cause lightning can be measured and theprobability of a lightning event predicted. However, it is not possible to predict the exact location where lightning willstrike since it has been known to attach to earth beyond the visible horizon.Lightning is extremely dangerous and unnecessary exposure should be avoided. The following recommendations are

advisable:(1) When possible, plan outdoor activities around the weather forecast. Although it is difficult to know exactly if a

storm will occur, the conditions that create lightning storms such as the meeting of high and low pressure systems arepredicted days in advance. On days when such weather patterns are forecast, avoid planning activities where shelter isnot readily available such as boating or camping.(2) Check the forecast the night before and the morning of planned outdoor activities to see if lightning is a possibility.(3) Check internet website weather maps before you leave. Most weather sites have recent satellite and radar images

of the area of your activity.(4) When you arrive at the area of your activity, devise a plan on where to go in the event of an approaching Lightning

Storm. Tell all persons in your party, especially children, where to go in accordance with section M.2.2. Also, tell yourparty where you will meet a half hour after thunder is last heard, since you may not be together when the threat of astorm arises.(5) Carry a weather radio with an Alert feature to receive severe weather warnings.(6) Respond accordingly when warnings are issued.M.2.2 If you hear thunder, seek shelter immediately. Do not try to predict how close lightning is by counting the time

between the flash of lightning and the sound of thunder. Stay indoors until one half hour after you last heard thunder.Seek shelter in structures such as the following:(1) Dwellings or other buildings that are protected against lightning(2) Underground shelters such as subways, tunnels, and caves(3) Large metal-frame buildings(4) Large unprotected buildings(5) Enclosed automobiles, buses, and other vehicles with metal tops and bodies(6) Enclosed metal trains and street cars(7) Enclosed metal boats or ships(8) Boats that are protected against lightning(9) City streets shielded by nearby buildings


Report on Proposals – June 2010 NFPA 780If caught in a Lightning Storm with no shelter available, the following rules should be observed when a location can be

selected:M.2.23 If possible, avoid places with little or no protection from lightning such as the following:(1) Small, unprotected buildings, barns, sheds, and so forth(2) Tents and temporary shelters(3) Automobiles (nonmetal top or open)(4) Trailers (nonmetal or open)M.2.34 Certain locations are extremely hazardous during thunderstorms and should be avoided if at all possible.

Approaching thunderstorms should be anticipated and the following locations avoided when thunderstorms are in theimmediate vicinity:(1) Hilltops and ridges(2) Areas on top of buildings(3) Open fields, athletic fields, golf courses(4) Parking lots and tennis courts(5) Swimming pools (indoor or outdoor), lakes, and seashores(6) Near wire fences, clotheslines, overhead wires, and railroad tracks(7) Under isolated trees(8) Near electrical appliances, telephones, plumbing fixtures, and metal or electrically conductive objectsM.2.45 It is especially hazardous to be riding in or on any of the following during thunderstorms while in the locations

described in M.2.3:(1) Open tractors or other farm machinery operated in open fields(2) Golf carts, scooters, bicycles, or motorcycles(3) Open boats (without masts) and hovercraft(4) Automobiles (nonmetal top or open)M.2.56 If caught in a Lightning Storm with no shelter available, the following recommendations should be observed:it is not always possible to choose a location that offers good protection from lightning, but the following rules should be

observed when a location can be selected:(1) Seek depressed areas -- avoid mountaintops, hilltops, and other high places.(2) Seek dense woods -- avoid isolated trees.(3) Seek buildings, tents, and shelters in low areas -- avoid unprotected buildings.(43) If caught in an exposed area, crouch as low as possible, kneel on the ground, keeping feet together, pPutting your

hands on your thighs knees. Do not place your hands on the ground. To minimize risk of direct strike, it is necessary tokeep as low as possible. To minimize risk of step potential hazards, it is necessary to minimize the area of the body incontact with the ground. Do not lie flat.M.3 Protection for Persons in Watercraft. Inasmuch as the basic purpose of protection against lightning is to ensure

the safety of persons, it is appropriate that the precautions and suggestions in M.3.1 through M.3.3 be listed in additionto all applicable recommendations in the preceding sections.M.3.1 One should remain inside a closed boat, as far as practical, during a lightning storm and should not dangle arms

or legs in the water.M.3.2 To the extent consistent with safe handling and navigation of the boat during a lightning storm, one should avoid

making contact with any items connected to a lightning protection system, especially in such a way as to bridge betweenthese items. For example, it is undesirable for an operator to be in contact with reversing gear levers and spotlightcontrol handle at the same time.M.3.3 No one should be in the water during a lightning storm.M.4 Lightning Safety For Outdoor WorkersM.4.1 DetectionM.4.1.1 Lightning Conditions are to be monitored continuously. In most cases, a combination of a lightning network

subscription service, a professional grade lightning warning system, and a high quality hand held detector is suggested.However, if thunder is heard, the danger from lightning is close enough to suspend operations and seek refuge.M.4.2 NotificationM.4.2.1 Suspension and resumption of work activities are planned in advance, through policies and training.

Information can be transmitted by some or all of the following methods:(1) Sirens(2) Strobe lights(3) Text messages(4) 2-way radios(5) Telephone


Report on Proposals – June 2010 NFPA 780M.4.2.2 A conservative warning threshold could be:Yellow condition: Lightning is in the 20-40 mile (30-60 km) range and the threat may exist.Orange condition: Lightning is in the 10-20 mile (16-30 km) range and the threat is nearby.Red Alert: Lightning is in the 0-10 mile (0-16 km) range and no personnel are allowed outdoors. All outside personnel

must seek safety in a designated shelter that is equipped with a lightning protection system that complies with thisstandard. If not available, seek shelter in the structures listed above in M.2.2.M.4.3 Reassess the Threat.M.4.3.1 Wait until one-half hour after thunder is no longer heard before resuming outdoor activities. Be extra cautious

during this storm phase as lightning still may be a significant hazard.M.4.4 Policies, Procedures, Education and Training.M.4.4.1 Organizations should create, publish and train personnel on appropriate lightning safety guidelines, in

accordance with the recommendations above.M.5 Lightning Strike VictimsM.5.1 Individuals that have been struck by lightning do not carry an electrical charge and are safe to assist.

Administer first aid and/or CPR immediately, if qualified. Get emergency help immediately.The TC edits the submitter's text. The change meets the submitter's intent.


RAPP, R.: There is no 9.9.9. Also the 24 months in this paragraph appears to be at variance with 9.9.7 which wouldmake this 14 months. paragraph 9.9.7.7 this paragraph seems to be at variance with 9.9.6.3 and 9.9.7.TOBIAS, J.: Thanks to Mr. Humeniuk & Personal safety task group for this useful revision. Well done!



_______________________________________________________________________________________________Richard Kithil, National Lightning Safety Institute (NLSI)

Add new text as follows:M.2.6 Lightning safety for outdoor workers depends on advanced threat recognition. "Move from a high risk situation to

a low risk location." A comprehensive lightning safety program can consist of the following details:M.2.6.1 Detection. Lightning conditions are to be monitored continuously. Some options are: a lightning network

subscription service; a professional-grade lightning warning system; weather warnings on TV; etc. Generally, if thunderis heard the danger is close enough to suspend operations and to seek refuge.

M.2.6.2 Notification. Suspension and resumption of work activities should be planned in advance. Information toworkers can be transmitted by some or all of --- sirens, strobe lights, text messaging, 2-way radio, telephone, verbal, etc.A conservative warning threshold could be:

Yellow Condition: 20-40 mi. (30-60 km).Orange Condition: 10-20 mi. (16-30 km).Red Alert: 0-10 mi. (0-16 km).

M.2.6.3 Safe Shelter. Safe evacuation sites include:a. Fully enclosed all-metal vehicles.b. Permanent, substantial buildings.c. Designated metal shelters especially designed.d. Other locations as identified by safety personnel.UNSAFE AREAS during thunderstorms include proximity to electrical equipment, metal objects, machinery, and

other conductors. AVOID rooftops. AVOID water. AVOID all open areas. AVOID tall trees.M.2.6.4 Re-Assess The Threat. Wait until thunder is no longer heard before resuming activities. Be extra cautious

during this storm phase as lightning still may be a significant hazard.M.2.6.5 Resume Normal Outdoor Activities When Notified.M.2.6.6 Policies & Procedures. Education & Training.

People who have been struck by lightning do not carry an electrical charge and are safe to assist. Apply first aidimmediately if you are qualified to do so. Get emergency help promptly

4.1 Annex M Presently does not address safety in the outdoor workplace where many lightningincidents occur.4.2 Our proposed changes are based upon some 15 years of work in this topical field.






Revise text as follows:O.1.2.4 UL Publications. Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062-2096.ANSI/UL 1449, UL Standard for Safety Transient Voltage Surge Suppressors Protective Devices, 1996 2006.

Update referenced standards to most current revision. Add ANSI designation for referenced standardthat meet the ANSI approval procedures.

Revise text as follows:O.1.2.4 UL Publications. Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062-2096.ANSI/UL 1449, UL Standard for Safety for Transient Voltage Surge Suppressors Protective Devices, 1996 2006.

The TC corrects the title of the UL 1449 document.


_______________________________________________________________________________________________780-98 Log #42


Revise text as follows:O.2.5 UL Publications. Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrook, IL 60062-2096.UL 452, UL Standard for Safety Antenna Discharge Units, 1993 2006, revised 2007.ANSI/UL 497, UL Standard for Safety Protectors for Paired Conductor Communications Circuits, 2001, revised 2004.ANSI/UL 497A, UL Standard for Safety Secondary Protectors for Communications Circuits, 2001, revised 2008.ANSI/UL 497B, UL Standard for Safety Protectors for Data Communications and Fire Alarm Circuits, 1999 2004,

revised 2008.ANSI/UL 497C, UL Standard for Safety Protectors for Coaxial Communications Circuits, 2001, revised 2008.

Update referenced standards to most current revision. Add ANSI designation for referenced standardthat meet the ANSI approval procedures.



committee on nfpa 780, and iec61312-1, .iec 62305-4, the deleted documents are no longer in...

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