On Sept. 12, 2012, Underwriters Laboratories (UL) notified all fire-resistive (FR) cable manufacturers that UL and ULC (UL Canada) were withdrawing all current listings for FR cable products conforming to the current UL 2196 and ULC S-139 standards. While an interim program was quickly developed, this meant all FR cable manufacturers were no longer permitted to place the UL or ULC mark on the following products:
• UL classified FR cable (FHJR)
• ULC listed FR cable (FHJRC)
• UL listed cable with “-CI” suffix (circuit integrity)
Additionally, all electrical circuit protective systems constructed with FR cable (FHIT) were removed from the UL certification directory, including mineral insulated (MI) cable systems covered under UL System 10 (FHIT 10). Soon thereafter, UL formed a panel to reexamine the 2196 testing standard. This effort is still ongoing.
In the interim, UL invited manufacturers of the formerly listed cable products to retest. The interim program focuses on two key points for initial testing of cable products:
1) The need to establish repeatability, with all the necessary system components; and,
2) Whether representative testing may be possible in some cases if the critical variables of the fire-resistive and CI cable systems are understood, and a worst-case configuration can be determined.
As of May 10, 2013, there have been two products that have been re-certified, resulting in the following two new UL listings:
• System 1850 (FHIT 1850): This system provides a listed 2-hour FR cable assembly only for MI cable products.
• System 120 (FHIT 120): This system provides a listed 1-hour FR cable assembly only for the family of metal jacketed thermoset insulated cable products that include MC type cable and also CI (circuit integrity) type cables for power limited application, such as fire alarm systems.
For additional information and specific product brands, search the UL Online Certifications Directory by keywords “1850” or “120” at database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/gfilenbr.html.
How does this affect you?
The 2011 NEC requires feeder circuit wiring in emergency systems (which typically means the life/safety branch of the emergency generator system) be protected with a 2-hour fire-resistance rating [700.10(D)(1)], in assembly occupancies for not less than 1,000 persons or in buildings above 75 feet in height with any of the following occupancies: assembly, educational, residential, detention and correctional, business, and mercantile. These requirements also apply to the emergency portion of the essential electrical system in health care occupancies [517.26 (meaning the life/safety and critical branches)].
Per 700.10(D)(1), feeder circuit wiring shall meet one of the following conditions:
1) Feeders are installed in a space or area that is fully protected by an automatic fire suppression system. This would include all above-ceiling spaces where emergency system feeders could be installed.
2) Be a listed electrical circuit protective system with a minimum 2-hour fire rating. This would include the FHJR cable products and FHIT systems that are now no longer listed by UL, with the exception (as of Dec. 21, 2012) of the MI products now covered under the new FHIT 1850 and thermoset MC products covered under FHIT-120.
3) Be protected by a listed thermal barrier system for electrical system components with a minimum 2-hour fire rating. This would include intumescent “conduit wrap” products available from various manufacturers.
4) Be protected by a listed fire-rated assembly that has a minimum fire rating of 2 hours and contain only emergency wiring circuits. This would include architectural assemblies that are listed in the UL Fire Resistance Directory, and the spaces enclosed by these assemblies may contain only emergency system wiring.
5) Be encased in a minimum of 2 inches of concrete.
Looking back at previous editions of the NEC, we see the 2005 and 2008 editions note similar requirements, with one significant change being the fire rating requirement. In these earlier editions of the Code, the following was stated in 700.9(D)(6):
“Be a cable listed to maintain circuit integrity for not less than 1 hour when installed in accordance with the listing requirements.” (Note the 1-hour requirement, as opposed to 2 hours.)
It should also be noted that prior to 2005 (i.e., 2002 and earlier editions of the NEC), the language in 700.9(D)(1)(1) read as follows:
“1) Be installed with buildings that are fully protected by an approved automatic fire suppression system.”
This change, which took effect in the 2005 NEC, is significant because emergency system cables were no longer considered to be protected simply by being located in a building with full sprinkler coverage. From 2005 on, all areas and spaces through which an emergency system cable passed (e.g., above finished ceilings) were now required to have sprinkler protection — or, alternatively, the installation could meet one of the other requirements noted in 700.10(D)(1) [for the 2011 edition] and 700.9(D)(1) [for the 2008 edition].
Prior to the removal of the FR cable products listing by UL, it was possible to run emergency system feeder circuit wiring in non-rated, “non-sprinklered” spaces that could also contain non-emergency circuit wiring, because of the availability of FR cable products, such as RHW-2, which met the listed electrical circuit protective system requirements of 700.10(D)(1)(2) noted above.
When UL removed its listing for all cable products used in listed electrical circuit protective systems, we were left with 700.10(D)(1)(1), (3), (4), and (5) as the only remaining options for complying with 700.10(D)(1) requirements. The subsequent approval by UL of System 1850 (FHIT 1850) has provided a limited (to one MI cable manufacturer) option for compliance via 700.10(D)(1)(2). Where the 2008 NEC is in effect, the MI option is supplemented by UL System 120 (FHIT 120), which provides a 1-hour rated installation as required by 2008 and earlier versions of the NEC
Why did this happen in the first place?
The reason UL removed the listings can be explained as follows.
UL received information that zinc in the system could affect the 2-hour rating. The concern regarding performance of these products is the presence of zinc, wherein circuit integrity was compromised by the reaction of the zinc with the copper conductor to form brass was validated. As a result of this validation, UL and ULC revised the guide information and individual certifications to exclude the use of zinc components.
During further research on a wide array of products, including conduits without zinc interior coating, systems and cables were not able to consistently achieve a 2-hour fire-resistive rating. Therefore, UL rescinded the listing, and a joint U.S. and Canada standards working group was formed. The group will determine what upgrades in requirements are necessary as well as focus on a strategy to address installation variables, sampling requirements for testing, and the need for further research.
It is important to note that other listings (i.e., other than fire resistance) on these cable products are not affected. UL removed the listing for MI products listed for System 10 (FHIT 10) and for MC-type products. The outcome of the new testing by one MI product manufacturer has resulted in all of its MI products passing tests and a new listing under system 1850 (FHIT 1850, 2 hour) being posted by UL that is specific to that manufacturer’s MI cable products. Also, one manufacturer of MC-type products has obtained a product-specific listing (FHIT-120, 1 hour). UL has confirmed that FHIT 1850 and FHIT-120 are now the only listed FR cable systems, although the invitation for other manufacturers to retest their products is still in effect.
It should be noted that fire alarm “CI” cabling was also among the cable types affected by this action.
Options for moving forward
MI cable products from a single manufacturer are the only FR cable products that satisfy the requirement for a 2-hour listed (FHIT-1850) electrical circuit protective system as noted in 700.10(D)(1)(2) of the 2011 NEC. In my experience, this product has seen limited use, primarily due to the cost of the product and the difficulty of installation. To date, fire pump feeders have been the most notable application for the MI product. For those jurisdictions that have not yet adopted the 2011 NEC and are still using the 2008 or earlier editions, there is also the option of using a single manufacturer’s 1-hour listed thermoset MC type cable products (FHIT-120).
Sprinkler protection of above-ceiling spaces is an option, but it comes with requirements for maintaining clear uncongested space such that the dispersion of water from the sprinkler heads to the protected cable is not blocked by ductwork and other elements typically located in these spaces. This can (and usually will) be a major problem in retrofit applications. Additionally, some jurisdictions do not favor “sprinklering” of electrical rooms, and, if so, that would lead to rating of the room as the preferred option for protecting feeders. Another consideration, especially where sprinkler protection of above-ceiling spaces may be required, is that such a design decision may not be obvious when subsequent renovations to the building are undertaken, which could lead to a decision to remove sprinklers originally installed in these spaces for feeder protection.
Since MI cable — from a single manufacturer at this point — has regained its listing, use of this product as a 2-hour fire-resistance-rated listed electrical circuit protective system is an option, and would be most practical (i.e., cost effective) in cases where the required system capacity is low (i.e., there would not be a requirement for large numbers of paralleled conductors). For those jurisdictions not yet enforcing the 2011 NEC, the use of 1-hour rated thermoset MC type cable (again, form a single manufacturer) is also an option. It is also possible that some jurisdictions may accept listings by agencies other than UL, should such listings be available. Given the nature of the testing failures, however, this seems unlikely.
Use of listed thermal barrier systems comes with high price, again, due to material cost and difficulty of installation. Protecting the feeders with listed fire-rated assemblies can also carry a significant cost. However, much of this can be “zeroed out” if the spaces for these electrical systems are assigned and configured with proper adjacencies and stacking in such a way as to inherently limit the amount of exposed cable runs required outside of 2-hour rated electrical equipment and shaft areas and spaces.
As a result of this action, UL-listed FR cable products are currently limited to MI cable and MC products from a specific manufacturer. Previously certified cable manufacturers have expressed an interest to UL in the interim program, and it is expected that additional certifications will be forthcoming in the near future. Updates on product certifications can be found at UL.com/fireratedcables.
For now, the options that remain for complying with the requirements of Art. 700.10 of the 2011 NEC using FR cable systems are limited and can prove to be very costly and difficult to implement. A more cost-effective option, especially for new construction, would be to plan electrical equipment spaces and pathways so as to minimize the need for FR cable systems, additional sprinkler work, or thermal barrier systems/supplemental pathway protection via extensive fire-rated construction.
Neithammer is an associate principal with Ballinger in Philadelphia. He can be reached at [email protected]. Research credit on this article is also given to Mike Ginder, a senior electrical engineer at Ballinger.
SIDEBAR 1: Where Are These SystemsTypically Located?
Fire-resistive, fire-resistant, and circuit integrity cables are primarily installed in mixed occupancy high-rise buildings, tunnels, bridges, and other commercial infrastructures. In many circumstances, the referenced systems exist in conjunction with other fire mitigation system options, which are not in question. Within a building or structure, the locations of these fire-resistive circuit cable systems are typically found as part of the following life safety installations:
• Fire pump-feeder/controls
• Smoke control equipment
• Command center critical systems
• Pressurized stairway systems
• Smoke management systems
• Fire alarm systems
• Electrical equipment rooms - feeders/service
• Emergency generators and standby power systems
Source: Underwriters Laboratories (UL)
SIDEBAR 2: Recommendations for Buildings/Structures with Installed Systems or Systems That are Awaiting Sign-Off
A Fire Safety Task Force consisting of representatives from UL’s Fire and Electrical Councils recently met and offers the following guidelines. Because of the variability in the design and construction of buildings and other structures that may have an electrical circuit integrity system (ECIS), it is difficult to determine if any corrective action is needed. We recommend that code authorities, contractors, architects, and building owners work with fire protection specialists to determine the reliance on these products and systems for code compliance and then decide if any action is required.
In determining if corrective action is necessary, we suggest you consider a performance approach to assess the building’s unique situation. First, employ a safety team to review and identify risks in the building (e.g., are there redundant systems in place, and is there a need for an additional fire mitigating system?). Specific to the installed or specified ECIS, guide the team to consider all relevant factors and variables, including, but not limited to, the following:
• Length of cable in ECIS
• Location and access of current system cable
• Redundant protection systems currently in place
• Is Critical Operations Power Systems (COPS) classification essential to owner?
• Number of stories in building
• Occupancy (type) of building
• Fuel loading
• Sprinkler coverage
• Fire alarm system coverage
Assessing these variables will help your team determine if any action is needed.
Source: Underwriters Laboratories (UL)