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Proposed Changes To The 2012 National Electrical Safety Code


National Electrical Safety Code C2-2007


Schedule 1 September 2009

Preprint of the change proposals for incorporation into the 2010 Edition of the NESC published for distribution to the NESC Committee and other interested parties. This opens the comment period, by interested parties, on the submitted change proposals and the subcommittee recommendations.

1 May 2010 The final date to submit comments on the submitted change proposal and the

subcommittee recommendations. All comments and recommendations on these proposals are due to the Secretary, NESC Committee.


Schedule – Cont’d September-October 2010

Period for NESC Subcommittee Working Groups and NESC Subcommittees to reconsider all recommendations concerning the proposed amendments and prepare final report.

15 January 2011 Proposed revision of the NESC, Accredited Standards Committee

C2, submitted to NESC Committee for letter ballot and to ANSI for concurrent public review.


Schedule – Cont’d 15 May 2011

NESC Committee approved revisions of the NESC submitted to ANSI for recognition as an ANSI Standard.

1 August 2011 Publication of the 2012 Edition of the NESC.


Section 1: IntroductionSection 2: Definitions Several CPs proposed to significantly revise and add to

Rule 010, Purpose; Rule 11, Scope; and Section 2, Definitions, to:

Harmonize the purpose and scope sections of the NESC and the NEC

Mitigate conflicts between the codes

Resolve the conflict in NEC 90.2(B)(5)b


Rule 215C: Grounding of Circuits, Supporting Structures, and Equipment – Non-Current Carrying Parts

All guys should be grounded or insulated.

Lists several requirements for guy insulators.

Clarifies that a guy’s electrical connection to an anchor is not an acceptable means of grounding.


Rule 218: Vegetation Management

Recommended that title should be changed to “Vegetation Requirements.”

Removed phrase “vegetation management should be performed as experience has shown to be necessary.” Refers reader to Rule 214A2.

Adds note to denote ANSI Standards A-300 and Z133.1 for information regarding vegetation management.


Rule 230B, 251B: Ice and Wind Loading for Clearances

Revises method for determining sags and clearances by elimination of the additive constant and increasing wind pressures accordingly.


Clearance Zone(for use with Rule 230B)

Zone 1 Zone 2 Zone 3Radial Thicknessof Ice (in) 0.5 0.25Horizontal Wind

Pressure (lbs/ft2) 4 8 4 8 9 10

Temperature (oF) 0 +15 +30Constand Added tothe Resultant (lbs/ft) 0.3 0.2 0.05

Clearance Zone (for use with Rule 230B)


CP3437: Rules 230B1, 250B, 250D;Figures 230-1 & 250-1;Tables 230-1, 230-2 & 251-1

Revises to add a fourth loading zone for temperate island use (below lat 25º).

Radial thickness of ice, wind pressure, temperature and constant are separated for altitudes 0- 9000 feet and above 9000 feet.

No loading is specified for extreme ice and concurrent wind for warm islands from 0- 25º lat, north or south.


Table 232-1, FN 7: Vertical Clearance of Wires, Conductors, and Cables Above Ground,Roadway, Rail, or Water Surfaces

For clearance to services, revises the phrase “where the height of a building does not permit the service drop to meet these values…” to “the clearance over residential driveways only may be reduced to…”

Removes the subjectivity of having to judge whether a building’s height will accommodate clearance.


Rule 234A: Clearance of Wires, Conductors, Cables, and Equipment from Buildings, Rail Cars, Swimming Pools and Other Installations- Application

Added a reminder statement that for horizontal clearances, both the “at rest” condition and the “blowout” condition must both be satisfied.


Rule 234E1: Clearance of Wires, Conductors, Cables or Unguarded Rigid Live Parts Installed Over Swimming Areas With No Wind Displacement

New wording (as a result of an interpretation request) that clarifies that spas including whirlpools, hot tubs, jacuzzis and other installations not suitable for swimming are not considered swimming pools.


Rule 234F2, Fig 234-4b: Clearance Envelope for Grain Bins Filled by Portable Augers, Conveyors or Elevators

Seeks to clarify clearance diagram to grain bins where the vertical requirements are referenced to grade instead of to the grain bin.


Rule 235C2b1(c): Vertical Clearance Between Line Conductors, Additional Clearances, Sag Related Clearances

Requirements for vertical clearance at the supports.

Recognizes that two vertical lines on the same support are at the same ambient but may be at different electrical loading and/or icing conditions.

Removes the exception for the same utility, same conductors at the same sags and tensions.


Rule 238:Vertical Clearance Between CertainCommunications and Supply Facilities Located on the Same Structure

Enforces official interpretation requests in ensuring that non-conductive wood or fiberglass braces and supports for communication conductors are not allowed in the worker safety zone.


Rule 250C- Extreme Wind Loading Rule 250DExtreme Ice With Concurrent Wind Loading

Proposal to exclude the 60’ exemption.

Status: Rejected- the proposals do not increase safety.


Proposed Changes to Rule 410A3- Arc Flash


1. Take Exception 2 and put it in rule. (For work where V< 1000 Volts: In lieu of analysis, limit exposure by applicable work rules and wear 4 cal/cm2 clothing).

2. Revise “…clothing made from the following materials…” to “clothing must have an acceptable arc rating” to make statement all inclusive.

3. Table 410-1 reword headings and footnotes.



QUESTIONS?

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Documents

nesc committee

oncor electric delivery

nesc subcommittees

purpose rule

loading zone

wind loading

subcommittee recommendations

submitted change proposals