In this issue:

An objective in model mechanical and

electrical codes and HVAC standards is

to protect life and property from fire and

smoke resulting from fires. One of the

protection methods used to accomplish

this objective involves restricting the

spread of smoke within a building by

minimizing the ignition sources and

combustibility of the elements within the

air handling systems.

Model codes and standards Model codes and standards address

combustibility of elements in air handling

systems, and define terms such as ducts,

plenums and air handling systems in

similar ways. While there are slight

differences throughout the Codes and

Standards on the terminology of ducts,

plenums or other spaces used for

environmental air, they fundamentally

seek to achieve the same end result in

the regulation of the construction and

materials used in air handling spaces.

Depending on whether the ventilation

compartment is a duct, plenum, or other

defined area, the codes may require

materials to be noncombustible or

constructed of specific materials with

identified surface burning and smoke

characteristics. For example, NFPA 90A

Products Used in Air Handling Spaces by John Taecker

(continued on page 5)

2008 ISSUE 4

2 Deck the Halls Safely This Year

6 Questions& Answers3 Understanding Panelboard

and Switchboard Short Circuit Current Ratings

7 NewsBriefs

A family member usually held

the base securely when it was

extended full-length to hang

lights on our second story roof

gutters, but I wondered what

would happen if the ladder failed.

The last thing I want to do is fall

off the ladder and face severe

injury or worse. This prompted

me to look up ladder safety tips,

which include the following:

Use wooden or fiberglass

ladders when near

power lines and electrical

wiring. Metal ladders

conduct electricity.

Use the right ladder for the

job, ensuring it extends 3

feet over the roofline or

working surface.

Set the ladder on a firm, level

surface and avoid soft or

muddy ground.

Never exceed the ladder’s

weight limit or the maximum

load rating.

Never stand on a step

ladder’s bucket shelf.

Read and follow the

warning stickers for

highest standing levels.

Have only one person on

the ladder.

Don’t carry equipment while

climbing. Wear a tool belt or

have someone hand

equipment to you.

Face the ladder when

climbing up or down, keeping

your body centered between

the side rails.

I added another personal safety

tip to this list, which was to not

trust a wobbly, 40+ year old

ladder just because it worked

well for my grandfather and

father. Accordingly, my early

Christmas present to myself

this year is a nice, new heavy-

duty extension ladder. For more

holiday decorating tips regarding

tree fire prevention, electrical

safety, ladder safety and candle

safety, see www.ul.com/newsroom/opdec/tips.html.Happy holidays!

Managing Editor

2008 Issue 4

02

While preparing to install our outdoor holiday lights this year I paused to examine the well-worn extension ladder I inherited from my grandfather. It always worked well, but over the past couple of years it seemed to have become a little wobblier each year.

The Code Authority

UL-eseDefinitions of terms

frequently used at UL

Repackages ProductsProducts repackaged from

bulk lots of UL Listed (or

other) products into smaller

packages and containers.

Repackagers of such

products may apply for

authorization to use a UL

Marking on their packages

under the Repackaged

Products program. The

repackaging program is

covered by an ongoing

follow-up services auditing

program to ensure the

repackaged products

continue to comply with

UL requirements.

www.ul.com/tca UL

Deck the Halls Safely This Year

2008 Issue 4

03The Code Authority UL

Understanding Panelboard and Switchboard Short Circuit Current RatingsQuestions often arise about how to install UL Listed panelboards and switchboards so that the overcurrent protective devices within the equipment have the ability to clear a fault without extensive damage to the equipment, as required by Sections 110.9 and 110.10 of the National Electrical Code (NEC).

Listed products installed and used in

accordance with their listing are considered

by the NEC to meet these requirements.

Short circuit current ratings (SCCR) and

available interrupting current (AIC) ratings

marked on the equipment provide the

information needed to provide a safe, code

compliant installation.

Circuit breakers and fuses are listed in

accordance with ANSI/UL 489 and UL 248

series standards, and are covered under

the DIVQ and JDDZ product categories,

respectively. These overcurrent protective

devices are marked with an interrupting

rating and must be sufficiently rated to

handle the available fault current at the

intended voltage of the overcurrent

protective device. Molded case circuit

breakers are required to be marked with the

AIC rating, when it exceeds 5000 amperes.

Panelboards and switchboards are Listed in

accordance with ANSI/UL 67 and ANSI/UL

891, and are covered under the QEUY and

WEVZ product categories, respectively.

This equipment is subjected to short circuit

tests1 using test current equal to its marked

maximum SCCR. After being subjected to

short circuit conditions, the mechanical

condition of the equipment must be

substantially the same as its condition prior

to the test, no live

parts can become

exposed, and

components within

the equipment cannot

be significantly

damaged.

The available fault

current for which the

panelboards and

switchboards must be

rated is typically found

on the electrical

one-line diagram. The

electrical engineer for

the project should

obtain the available

fault current from the

serving utility com-

pany and then calculate the available fault

current for all panelboards and switch-

boards in the electrical system. Once the

available fault currents are identified, the

system can be designed to provide an

acceptable level of short circuit protection

using methods referred to as either fully

rated systems or series rated systems.

Fully rated systems —

In the most simplistic terms, a fully rated

system is one in which all of the electrical

equipment (panelboards, switchboards,

and overcurrent protective devices) is

installed with SCCR or AIC ratings equal to

or greater than the available fault current to

which they might be subjected.

For example, if a panelboard has a 65K

ampere SCCR, with 65K ampere AIC rated

circuit breakers, the “full rating” (SCCR) is

65K ampere. See Fig. 1. If the panelboard

has a 65K ampere SCCR, with 22K ampere

(continued on next page)

1 The UL Standards allow exceptions to this testing under certain conditions.

AIC rated circuit breakers, the “full rating”

is 22K ampere. Conversely, if the panel-

board has a 65K ampere SCCR with a

100K ampere AIC rated circuit breaker, the

“full rating” is still 65K. In other words, the

“full rating” of a panelboard or switchboard

is based on the lowest rating of either the

equipment or any of the overcurrent

protective devices installed within

the equipment.

Series rated systems — NEC Section

240.86 includes requirements that allow a

circuit breaker to be used on a circuit

having an available fault current higher than

the marked interrupting rating, provided it is

connected on the load side of an accept-

able overcurrent protective device having a

higher rating, and provided that the series

combination complies with specific

requirements. The combination of these

devices has been found to work together

under fault conditions to clear the fault and

protect the equipment. This combination is

referred to as a series rated system.

UL series rated combinations are subjected

to short circuit testing using test currents

equal to the panelboard or switchboard’s

maximum rated short circuit current2.

The system is tested with (1) a line side

overcurrent protective device of the

maximum overcurrent rating, and (2) a load

side circuit breaker with the lower AIC

rating, as specified in the panelboard or

switchboard’s markings. The series rated

system is subjected to short circuit testing

in accordance with the UL 489 require-

ments for series

combinations.

See Fig. 2.

Markings— Listed panel-

boards and

switchboards are

required to be

marked with their

electrical ratings,

including their

SCCR. A typical

marking would

read, “Short-Cir-

cuit-Current Rating

65,000 RMS

symmetrical

amperes”. If the

unit contains

meter mounting

equipment other

than those for use

with current

transformers, they

are also marked

“Watthour meter

not included in

short-circuit-

current rating”.

Panelboards and switchboards that have

been investigated for use as series rated

systems include additional markings that

identify the combinations of integral or

remote line and load side overcurrent-pro-

tective devices that are required to achieve

the marked SCCR. See Fig. 3.

The marking is provided either on the

panelboard or switchboard. Alternately, the

marking may be provided in a pamphlet,

manual or instruction sheet located on or in

a pocket provided within the panelboard.

by Jeff Fecteau

For additional information on this topic

please refer to the 2008 UL White Book,

the Marking Guides for Panelboards,

Dead Front Switchboard and Molded Case

Circuit Breakers, or contact Jeff Fecteau

at Jeffrey.Fecteau@us.ul.com or at

+1.952.838.5453.

2008 Issue 4

04The Code Authority UL

Available FaultCurrent 65K amps

Main Circuit Breaker65K AIC

Utility Transformer Panelboard65K SCCR

Overall 65K amp rating

Branch CircuitBreakers 65K AIC

Available FaultCurrent 65K amps

Main “Type A”Circuit Breaker65K AIC

Utility Transformer Panelboard65K SCCR

Overall 65K amp rating

Branch “Type B”Circuit Breaker 10K AIC

Figure 1: Example of fully rated system

Figure 2: Example of series rated system

Branch Circuit Breaker Main Circuit Breaker Interrupting Rating

Type Amps No. Poles AIC Rating Type Amps No. Poles AIC Rating Symmetrical Amps V Ph

B 15–50 1 10,000 A 100 2 65,000 65,000 120/240 1

Figure 3: Example of series rated system for example in Fig. 2

Field markings for series rated systemsReplacing an overcurrent device in a

series rated system with one that has

not been investigated as part of the

combination can result in significant

safety concerns. In order reduce the

risk of an improper replacement circuit

protective device being installed,

NEC Section 110.22 (C) requires the

equipment enclosure(s) to be legibly

marked in the field by the installer to

indicate the equipment has been

applied with a series combination

rating. The marking shall be readily

visible and state the following:

CAUTION — SERIES COMBINATION

SYSTEM RATED ____ AMPERES.

IDENTIFIED REPLACEMENT

COMPONENTS REQUIRED.

Understanding Short Circuit Current Ratings (continued from previous page)

2 Testing using worst-case combinations may be representative of other combinations.

Section 4.3.10.2 requires materials

exposed to the airflow in ceiling cavity

plenums used for supply, return or exhaust

air from the occupied area to be noncom-

bustible, limited combustible, or have a

flame spread index not exceeding 25 and

a smoke-developed index not exceeding

50. Similarly, IMC Section 602.2.1 requires

materials exposed within plenums to be

noncombustible or to have a flame spread

index not more than 25 and a smoke-

developed index not more than 50. NFPA

90A, the NEC, the IMC, and the UMC all

include specific requirements for various

products used within plenums and other

air handling spaces, such as wiring, fire

sprinkler piping, pneumatic tubing,

combustible electrical equipment, light

diffusers, optical fibers and raceways,

loudspeakers, and/or recessed luminaires.

Refer to the code or standard in question

for specific requirements.

Testing for fire and smoke characteristicsMany materials used in plenums are

required to have a maximum flame spread

index of 25 and a maximum smoke

developed index of 50 when tested to UL

723 Test for Surface Burning Characteris-

tics of Building Materials (ASTM E84).

Using the Steiner Tunnel test apparatus,

test specimens measuring a nominal 2-ft

wide by 24-ft long are subjected to a 4-1/2

foot long flame. The time for flame

progression is measured and calculated as

a flame spread index. Also smoke obscu-

ration is measured and calculated as a

smoke developed index. Due to the test

specimen size, this standard could not be

used to test small discrete objects, such

as fluorescent ballasts and speakers.

A family of standards was developed to

test for flame spread and smoke density

for other products used in air handling

spaces such as wire and cable, fire

sprinkler pipe, and pneumatic tubing.

These methods use the same Steiner

Tunnel test apparatus as UL723, but the

sample mounting and testing criteria differ.

These standards are NFPA 262, Test

Method For Fire and Smoke Characteris-

tics of Electrical and Optical-Fiber Cables

Used in Air-Handling spaces; UL 1887, Fire

Test of Plastic Sprinkler Pipe for Visible

Flame and Smoke Characteristics; and UL

1820, Fire Test of Pneumatic Tubing for

Flame and Smoke Characteristics.

Materials tested to these standards are

required to exhibit a maximum flame

spread distance of 5 ft, a maximum peak

optical density of 0.5, and a maximum

average optical density of 0.15.

The Standard used to evaluate fire

performance and smoke-production

characteristics of smaller discrete objects

is UL 2043, “Fire Test for Heat and Visible

Smoke Release for Discrete Products and

Their Accessories Installed in Air-Handling

Spaces”. Products are subjected to a 60

kW ignition source, and all products of

combustion are arrested by a calorimeter

hood. Heat energy is determined using

oxygen consumption techniques and

equipment in the air stream determines

smoke density. To be acceptable, prod-

ucts are required to exhibit a peak heat

release rate of 100 kW or less, a maximum

normalized peak optical density of 0.5, and

an average normalized optical density of

0.15 or less.

These standards allow the fire perfor-

mance and smoke characteristics of these

various components to be determined and

quantified, and as a result, they have been

adopted by reference into IAPMO, ICC,

and NFPA model codes.

Products certified for use in plenumsUL certifies a number of products for use

in plenums, ducts and other space used

for environmental air. These certifications

can be found in the UL Online Certifica-

tions Directory at www.ul.com/database/,

Building materials — Material, such as

acoustical panels, pipe insulation and

coverings, duct coverings, insulation,

vapor retarder facings, adhesives, and

ducts have been Classified by UL in

accordance with UL 723 for flame spread

and smoke developed indices. These

products, or their packaging, are marked

with the specific indices, or are marked

“FHC 25/50”.

Wiring — Electrical cables and raceways

that comply with NFPA 262 are identified

with a suffix “P” on the cable designation

(such as CMP, CL2P, or FPLP). These

cable and raceway categories include

DUZX, DVCS, HNIR, QAYK, and QPTZ.

Fire sprinkler piping — All UL Listed

CPVC sprinkler pipe and fittings (VIWT)

comply with UL 1887. These products are

not required to be marked for use in

plenums. However, Listed support devices

for the sprinkler piping (VIXH) and cover

systems for the sprinkler piping (VIXO)

have not been evaluated to UL 1887,

unless specifically marked for plenum use.

Pneumatic tubing — UL Classified

pneumatic tubing (QNVT) that has been

tested and found to comply with UL 1820

is required to be marked “NFPA 90A”. (This

should be suitable for use in either a NFPA

90A, UMC or IMC application.) .

Combustible electrical equipment —

Most products tested and found to comply

with UL 2043, such as ballasts, loud-

speakers, recessed luminaires, information

technology equipment, wire positioning

devices, germicidal lamps, and other air

duct accessories, are provided with a

marking or installation instruction which

states “Suitable for Air Handling Spaces”,

“Suitable for Use in Other Environmental

Air Space in Accordance with Section

300.22(c) of the National Electrical Code,”

or similar wording.

Some recessed air handling

luminaires (HYXT) are restricted to

certain air handling applications, and

include markings that identify the

intended application.

For more information on products

certified for use in plenums, ducts and

air handling spaces, contact Dwayne

Sloan in Research Triangle Park, NC

at +1.919.549.1676, or at

Dwayne.E.Sloan@us.ul.com

2008 Issue 4

05The Code Authority UL

Air Handling Spaces (continued from cover)

I have recently heard about flexible sprinkler piping. Can you advise what it is, where it can be used, what are its limitations, and is it UL Listed?

Flexible sprinkler piping is UL Listed under

product category VENF as “Flexible

Sprinkler Hose with Fittings.” This category

covers flexible sprinkler hose with fittings

intended for use in sprinkler systems

between the branch line and sprinkler

when installed in accordance with ANSI/

NFPA 13, “Standard for the Installation of

Sprinkler Systems;” ANSI/NFPA 13R,

“Standard for the Installation of Sprinkler

Systems in Residential Occupancies up to

and Including Four Stories in Height;” or

ANSI/NFPA 13D, “Standard for the

Installation of Sprinkler Systems in

One- and Two-Family Dwellings and

Manufactured Homes,” and the

manufacturer’s installation instructions.

A flexible sprinkler hose assembly consists

of a flexible hose, inlet fitting for

connection to the branch line and an outlet

fitting for connection to the sprinkler.

These flexible hose with fittings are

intended to be installed using the

anchoring devices referenced in the

manufacturer’s installation instructions.

Flexible hose length is limited to a

maximum of 6 feet so as to minimize the

potential for inadequate support and

undesirable movement of a sprinkler after

installation. UL’s Listing information

includes additional information relative to

proper use such as allowable number of

bends, minimum bend radii, pressure loss,

type of flexibility and maximum

temperature rating. The manufacturer’s

installation instructions include additional

information such as anchoring device

installation procedures and sprinklers to

be attached to the outlet fitting.

As indicated in the individual Listings,

these products may have high flexibility or

limited flexibility. Products having high

flexibility are intended for use in

applications where frequent movement

between the two ends of the hose is

expected after installation. Products

having limited flexibility are intended for

use in applications where little or no

movement between the two ends is

expected after installation.

These products are intended for use in

hydraulically-designed sprinkler systems.

The hydraulic pressure loss associated

with these devices needs to be included in

the hydraulic design calculations. Pressure

loss is published in equivalent length, in

feet of 1-in. diameter Schedule 40 steel

pipe (where the Hazen-Williams coefficient

of friction is C equals 120).

The basic standard used to investigate

products in this category is UL 2443,

“Flexible Sprinkler Hose with Fittings for

Fire Protection Service.” Authorities Having

Jurisdiction should be consulted before

installation.

For additional information on flexible

sprinkler hose with fittings contact

John Bender at +1.443.567.8241,

or at John.Bender@us.ul.com.

2008 Issue 4

06The Code Authority UL

Questions & AnswersUL engineers answer questions concerning UL and its operations, UL Standards for Safety, product certifications, and the code applications for which products are certified.

2008 Issue 4

07The Code Authority UL

Global Fire Service Leadership Conference a SuccessUL launched The Global Fire Service

Leadership Conference on September 19,

2008. The conference, the first of its kind,

was fully developed and sponsored by UL,

and attendees included leading fire

experts and industry leaders from more

than 19 countries.

The conference provided fire service

leaders from some of the world’s largest

jurisdictions the opportunity to share best

practices and return home with a global

perspective on the issues that most

commonly wreak havoc and endanger

lives in fire, disaster and emergency

situations. Best practices, management

and leadership skills and life safety issues

facing the fire industry today were dis-

cussed in Chicago between September

21-24, then continued in Washington D.C.

through September 26.

“The reality is that regardless of where you

live, accidental death and property loss

from fires or natural disasters are global

concerns; materials and products found in

our homes or buildings burn in the same

manner in Chicago, Beijing, New York,

Delhi, Buenos Aires,

and every city in

between.” said Chris

Hasbrook, vice

president and general

manager of UL’s

Global Fire Sector.

“The challenges

faced by fire fighters

around the world

often share more

commonality than we

realize. The wealth of knowledge these

leaders exchange may eventually keep us

all safer from fire and disaster.”

UL Science of Safety Webinars Now OnlineUL’s Science of Safety Webinar series is

available for online viewing. The series

originated as an open forum for the fire

community to share information and

discuss fire safety topics with UL subject

matter experts. Sessions include:

“Smoke Alarms: Advancement in

Research and Requirements,” included a

presentation on smoke alarms and a panel

discussion with UL and International

Association of Fire Chiefs representatives.

“Smoke Alarms: Ionization, Photoelectric

and Dual Technology,” delved further into

the science behind the requirements and

demonstrated the differences in the

various technologies.

“The Threat of Modern Fires,” looked at

the science behind the threat of fires in

modern home environments.

“Firefighter Safety Research,” provided

information on UL research related to

firefighter safety. The session featured

panelists from the Chicago Fire Department

and International Association of Fire Chiefs.

To access the recorded Webinars visit

www.ul.com/ss/SafetyAdvancements.html and select the Webinar you would

like to view.

News Briefs

What’s new @ UL.com

The Regulators page of UL.com (www.ul.com/regulators) was developed specifically for you, the regulatory authority. Here are the most recent additions:

The Regulators page of UL.com

(www.ul.com/regulators) was

developed specifically for you, the

regulatory authority. Here are the most

recent additions we hope you find useful:

The Code Authority — Electrical

Connections — The October 2008

issue of The Code Authority — Electrical

Connections is available Online at

www.ul.com/tca. Learn why regulatory

authorities look for the UL Mark.

The Fire & Security Authority® — Issue

3 of the Fire & Security Authority is

available Online at www.ul.com/fsa. This

issue takes a look at noncombustible

building materials, UL’s updated

holographic label, UL Listed security

container modifications and the new

UL Listed Document.

Ultimate Email — Regulatory Services

offers a free subscription service that

allows you to get the regulatory news

that interests you delivered to your

mailbox via the Ultimate Email system.

Get public notices, newsletters and

topical announcements by signing up at

www.ul.com/regulators/contact.cfm.

You put in you information, tell us what

interests you and we send you infor-

mation that is relevant to you. No spam,

no selling your information — from its

inception, this database has been about

sharing relevant information with the

regulatory community. Sign up or tell a

friend. If you forget the link, just re-

member www.ul.com/regulators and

look to the right for the Ultimate Email

banner. We hope to hear from you!

ULU Training Courses for AHJs —

There are now eight training courses

for AHJs on our UL University website,

including our newest course covering

the structural stability of engineered

lumber in fire conditions. See

www.uluniversity.us/home.aspx.

If there is something you would like

to see on the Regulators page, send

your suggestions to Heather Kile in

Northbrook, IL at Heather.Kile@us.ul.com.

ul.comul.com

Calendar of Events

2008 Issue 4The Code Authoritywww.ul.com/tca UL

08

Underwriters Laboratories Inc.333 Pfingsten RoadNorthbrook, IL 60062-2096United States of America

The Code Authority®

Published by Regulatory Services

Department Underwriters Laboratories®

Available to assist regulatory authorities

W:: ul.com/regulators

T:: +1.800.595.9844

E:: ULRegulatoryServices@us.ul.com

Managing Editor

Howard Hopper

T:: +1.408.754.6609

E:: Howard.D.Hopper@us.ul.com

Editor

Heather Kile

T:: +1.847.664.1265

E:: Heather.Kile@us.ul.com

Address changes and additions

Diane Fonzino

E:: Diane.E.Fonzino@us.ul.com

© 2008. All rights reserved.

Reprints with permission of

Underwriters Laboratories Inc.®

BDI 080515

If you would like

The Code Authority to

consider publishing your

upcoming events, contact

Heather Kile, editor, by fax at

1.847.407.1265; or by email

at Heather.Kile@us.ul.com.

Please type “Calendar” in

the subject line.

December 8–12ICC Residential Inspection InstituteSeattle, WA

www.iccsafe.org

December 15–19NFPA Professional Development Seminar WeekOrlando, FL

www.nfpa.org

January 16–19, 2009Building Owners and Managers Association (BOMA) International Winter Business Meeting and Leadership ConferenceIndian Wells, Calif.

www.boma.org

January 24–282009 American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Winter ConferenceChicago, IL

www.ashrae.org