Products Used in Air Handling Spaces by John Taecker

Transcription

1 2008 ISSUE 4 Products Used in Air Handling Spaces by John Taecker 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 (continued on page 5) In this issue: 2 Deck the Halls Safely This Year 3 Understanding Panelboard and Switchboard Short Circuit Current Ratings 6 Questions & Answers 7 News Briefs

2 The Code Authority 02 -ese Definitions of terms frequently used at Repackages Products Products repackaged from bulk lots of Listed (or other) products into smaller packages and containers. Repackagers of such products may apply for authorization to use a 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 requirements. Deck the Halls Safely This Year 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. 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 heavyduty extension ladder. For more holiday decorating tips regarding tree fire prevention, electrical safety, ladder safety and candle safety, see newsroom/opdec/tips.html. Happy holidays! Managing Editor

3 Understanding Panelboard and Switchboard Short Circuit Current Ratings Questions often arise about how to install 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 and of the National Electrical Code (NEC). 03 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/ 489 and 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/ 67 and ANSI/ 891, and are covered under the QEUY and WEVZ product categories, respectively. This equipment is subjected to short circuit tests 1 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 company and then calculate the available fault current for all panelboards and switchboards 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 Standards allow exceptions to this testing under certain conditions.

4 04 Understanding Short Circuit Current Ratings (continued from previous page) AIC rated circuit breakers, the full rating is 22K ampere. Conversely, if the panelboard 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 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 acceptable overcurrent protective device having a higher rating, and provided that the series Available Fault Current 65K amps Utility Transformer Main Circuit Breaker 65K AIC Figure 1: Example of fully rated system Available Fault Current 65K amps Utility Transformer Main Type A Circuit Breaker 65K AIC Figure 2: Example of series rated system Panelboard 65K SCCR 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. series rated combinations are subjected to short circuit testing using test currents equal to the panelboard or switchboard s maximum rated short circuit current 2. 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 489 requirements for series combinations. Branch Circuit Breakers 65K AIC Branch Type B Circuit Breaker 10K AIC Panelboard 65K SCCR Overall 65K amp rating Overall 65K amp rating See Fig. 2. Markings Listed panelboards and switchboards are required to be marked with their electrical ratings, including their SCCR. A typical marking would read, Short-Circuit-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-circuitcurrent 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-protective 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 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 Field markings for series rated systems Replacing 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 (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. 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 ,000 A ,000 65, /240 1 Figure 3: Example of series rated system for example in Fig. 2 2 Testing using worst-case combinations may be representative of other combinations.

5 05 Air Handling Spaces (continued from cover) Section requires materials exposed to the airflow in ceiling cavity plenums used for supply, return or exhaust air from the occupied area to be noncombustible, limited combustible, or have a flame spread index not exceeding 25 and a smoke-developed index not exceeding 50. Similarly, IMC Section requires materials exposed within plenums to be noncombustible or to have a flame spread index not more than 25 and a smokedeveloped 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 characteristics Many 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 723 Test for Surface Burning Characteristics 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 obscuration 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 723, but the sample mounting and testing criteria differ. These standards are NFPA 262, Test Method For Fire and Smoke Characteristics of Electrical and Optical-Fiber Cables Used in Air-Handling spaces; 1887, Fire Test of Plastic Sprinkler Pipe for Visible Flame and Smoke Characteristics; and 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 The Standard used to evaluate fire performance and smoke-production characteristics of smaller discrete objects is 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, products 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 performance 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 plenums certifies a number of products for use in plenums, ducts and other space used for environmental air. These certifications can be found in the Online Certifications Directory at Building materials Material, such as acoustical panels, pipe insulation and coverings, duct coverings, insulation, vapor retarder facings, adhesives, and ducts have been Classified by in accordance with 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 Listed CPVC sprinkler pipe and fittings (VIWT) comply with 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 1887, unless specifically marked for plenum use. Pneumatic tubing Classified pneumatic tubing (QNVT) that has been tested and found to comply with 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 2043, such as ballasts, loudspeakers, 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 (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 , or at Dwayne.E.Sloan@us.ul.com

6 06 Questions & Answers engineers answer questions concerning and its operations, Standards for Safety, product certifications, and the code applications for which products are certified. 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 Listed? Flexible sprinkler piping is 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. 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 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 , or at John.Bender@us.ul.com.

7 News Briefs 07 Global Fire Service Leadership Conference a Success launched The Global Fire Service Leadership Conference on September 19, The conference, the first of its kind, was fully developed and sponsored by, 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 discussed 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 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. Science of Safety Webinars Now Online 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 subject matter experts. Sessions include: Smoke Alarms: Advancement in Research and Requirements, included a presentation on smoke alarms and a panel discussion with 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 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 html and select the Webinar you would like to view. What s ul.com The Regulators page of.com ( was developed specifically for you, the regulatory authority. Here are the most recent additions: The Regulators page of.com ( 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 Learn why regulatory authorities look for the Mark. The Fire & Security Authority Issue 3 of the Fire & Security Authority is available Online at This issue takes a look at noncombustible building materials, s updated holographic label, Listed security container modifications and the new Listed Document. Ultimate 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 system. Get public notices, newsletters and topical announcements by signing up at You put in you information, tell us what interests you and we send you information 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 remember and look to the right for the Ultimate banner. We hope to hear from you! U Training Courses for AHJs There are now eight training courses for AHJs on our University website, including our newest course covering the structural stability of engineered lumber in fire conditions. See 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.

8 The Code Authority 08 Calendar of Events The Code Authority Published by Regulatory Services Department Underwriters Laboratories Available to assist regulatory authorities W:: ul.com/regulators T:: E:: Managing Editor Howard Hopper T:: E:: Editor Heather Kile T:: E:: Address changes and additions Diane Fonzino E:: All rights reserved. Reprints with permission of Underwriters Laboratories Inc. BDI If you would like The Code Authority to consider publishing your upcoming events, contact Heather Kile, editor, by fax at ; or by at Please type Calendar in the subject line. December 8 12 ICC Residential Inspection Institute Seattle, WA December NFPA Professional Development Seminar Week Orlando, FL January 16 19, 2009 Building Owners and Managers Association (BOMA) International Winter Business Meeting and Leadership Conference Indian Wells, Calif. January American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Winter Conference Chicago, IL Underwriters Laboratories Inc. 333 Pfingsten Road Northbrook, IL United States of America