Guide
Authored by:
Chris P. James, Principal Engineering Manager, UL Solutions, and Distinguished Member of Technical Staff — William Henry Merrill Society
Allan P. Sanedrin, Principal Engineer, UL Solutions, and Distinguished Member of Technical Staff — William Henry Merrill Society
For code authorities, review of fire-resistive cable systems starts with two questions: Does the installed system comply with the certified system, and has it been evaluated for circuit integrity and/or signal integrity under fire conditions?
Those questions reflect a shift in how fire-resistive cables are evaluated. The third edition of UL 2196, the Standard for Fire Test for Circuit Integrity of Fire-Resistive Power, Instrumentation, Control and Data Cables, evaluates more than whether the circuit maintains electrical continuity. It also addresses whether data and communication cables can support a defined signal performance during a fire event.
Understanding that shift begins with defining what makes a cable system "fire-resistive."
A fire-resistive cable system is defined as an assembly of components installed together to protect specific electrical wiring against the loss of circuit integrity and/or data transmission during a fire event. The hourly rating is defined by the installation with either one-hour or two-hour ratings being the requirement within most model codes. This hourly fire rating applies only to the complete fire-resistive cable system, which typically consists of a combination of a cable, connectors, clamps, supports, raceway, pull boxes and splices that was tested and certified together. A UL Certified cable paired with the wrong connector, clamp or raceway is no longer the system that obtained the hourly fire rating. Any modification after UL Certification requires a retest of the entire system.
Fire-resistive cable systems may be used where certain circuits are required to remain operational during a fire event, including high-occupancy and high-risk facilities such as high-rise buildings, healthcare facilities and transit tunnels.
Authorities having jurisdiction (AHJ) may encounter these requirements across several codes. In NFPA 70, National Electrical Code® (NEC), the relevant articles include Article 695 ("Fire Pumps"), Article 700 ("Emergency Systems"), Article 708 ("Critical Operations Power Systems"), Article 722 ("Cables for Power-Limited Circuits and Fault-Managed Power Circuits"), Article 760 ("Fire Alarm Systems") and Article 772 ("Fire-Resistive Cable Systems"). The International Building Code (IBC) and International Fire Code (IFC) add requirements in Chapter 9 (“Fire Protection and Life Safety Systems”), Chapter 27 ("Electrical") and Chapter 30 ("Elevators and Conveying Systems").
UL 2196 supports code-related applications addressed in NFPA 70, NFPA 72, NFPA 130, NFPA 502 and NFPA 1225, as well as the International Building Code.
Certification to UL 2196 involves a sequence of fire endurance, hose stream and mechanical evaluations using standardized test methods intended to assess circuit integrity during fire exposure.
Before any test begins, the manufacturer installs the complete system on a fabricated wall as it would appear in the field. How the system is built, and which components are used, is what is certified. Field modifications can impact whether the system maintains compliance with the certified system and the accompanying manufacturer’s installation instructions. The manufacturer’s installation instructions are reviewed as part of the certification evaluation process.
The assembly is placed into a vertical furnace that follows the time-temperature curve provided in UL 263, the Standard for Fire Tests of Building Construction and Materials, and ASTM E119, Test Methods for Fire Tests of Building Construction and Materials, using the values below. These values only include up to a two-hour duration but extend up to eight hours:
When testing power cable systems, at least 10 samples are required; in contrast, 12 samples are required for data and communication cables. These samples are split between horizontal and vertical orientations, with horizontal samples including at least one 90-degree bend. Cables must terminate no more than 3.0 m (120 in.) beyond the furnace confines, with no cable closer than 305 mm (12 in.) from the furnace wall. Throughout the fire endurance test, 10 samples are energized and monitored for any loss of continuity, while the additional two samples are monitored for data transmission quality.
Within five minutes of the fire endurance test ending, the assembly is subjected to a hose stream — first at the bottom center, then across the full exposed surface — from a nozzle 20 feet away. The cable system must withstand the erosion, cooling and force of the water and still maintain its circuit integrity and data/communication transmission requirements. The water pressure and duration are directly impacted by the hourly rating of the test assembly, drawing on the methodology in UL 10B, the Standard for Fire Tests of Door Assemblies.
During the fire endurance test, a weight is secured to the bottom of a vertical sample using the smallest conductor size. The weight represents the unsupported cable length, testing whether the cable can carry its own load as its structure degrades under fire conditions.
Throughout the fire endurance test and after the hose stream, the system is evaluated for electrical continuity. Confirmation comes through visual indicators for open circuits, and a 3 A Class K, non-time-delay fuse placed in each ungrounded conductor for short circuits.
Historically, such cables were only evaluated for electrical continuity. But a fire alarm or emergency voice system cable can technically maintain acceptable continuity while the signal can have unacceptable degradation. Continuity alone may not demonstrate that a cable can support the communication performance expected in a fire and life safety signaling system.
That concern is consistent with research published by the NFPA Fire Protection Research Foundation in 2022, which examined whether elevated temperatures can affect the transmission and functional quality of alarm/data signals and voice messages in pathway-survivable cables used for life safety systems, including emergency voice/alarm communication systems (EVACS) and emergency responder communications enhancement systems (ERCES).[1] The report found that fire-related signal impacts are possible, though researchers did not find documented evidence of those impacts in EVACS or ERCES installations. The issue is not that every survivable pathway is known to lose signal quality during a fire — it is that continuity alone may not provide enough information about how voice, data or radio frequency (RF) signals perform as heat, water exposure and mechanical stress affect the installed pathway.
The report also found no scientific studies showing that fire-rated enclosures or sprinkler systems specifically mitigate thermally induced data or voice signal degradation in cables, although those protections can reduce the temperatures to which cables are exposed. Knowing whether the circuit remains intact is not the same as knowing what communication performance the cable system was tested to support under defined fire conditions.
The third edition of UL 2196 requires data and communication cables to maintain acceptable signal integrity in accordance with the manufacturer's performance specifications while also maintaining circuit integrity throughout both the fire endurance test and the hose stream test.
Two details are particularly important when interpreting a manufacturer's performance specifications. First, UL 2196 permits manufacturers to define performance specifications for both normal operating conditions and conditions following exposure to the fire endurance and hose stream tests. These specifications are to be based on recognized industry standards, such as those published by the Telecommunications Industry Association (TIA) or the International Electrotechnical Commission (IEC), applicable military specification sheets or other accepted standards.
Second, compliance with the manufacturer's performance specifications is evaluated through testing. Data acquisition is performed every five minutes throughout the entire fire endurance test. Following the hose stream test, measurements are taken within five minutes of test completion and then recorded at five-minute intervals for a minimum of 30 minutes. This approach allows signal performance to be monitored throughout the testing process rather than being evaluated only at the conclusion of testing.
ERCES are in-building radio systems that enable emergency responders to communicate with one another within a building or with their incident command teams at the exterior of the building, when the building's construction, such as concrete, steel or below-grade areas, would otherwise impair radio signal coverage. A responder's radio transmission travels through the building's distributed antenna system to a signal booster, then through the backbone cable to an exterior antenna. Model codes, local jurisdictions or project specifications may require ERCES equipment or systems to be certified to UL 2524, the Standard for Emergency Responder Communication Enhancement Systems.
The rapid growth of ERCES installations was a major driver behind the changes to UL 2196. As such, an appendix was added to provide guidance for testing coaxial cable used in distributed antenna systems, a common configuration in ERCES installations. The guidance addresses the applicable cable type, coaxial cable; the performance characteristics to be evaluated, including insertion loss (IL), return loss (RL), and voltage standing wave ratio (VSWR); and the test equipment used to assess performance, such as a vector network analyzer and signal generator.
UL 2196 applies to many types of cable, including coaxial, twisted-pair, fiber-optic and other communication cables. The signals transmitted over these cables and the performance attributes that define acceptable operation can vary significantly. By allowing compliance to be evaluated against a manufacturer's published performance specifications rather than enforcing a universal pass-fail threshold, UL 2196 provides a flexible approach that recognizes the differing tolerances of different fire and life safety systems to signal degradation.
Product iQ® is an online database for architects, engineers, contractors, manufacturers and code authorities to search for, verify and confirm UL Certified products, components and materials. During plan review or inspection, code authorities can use it to confirm whether the specified or installed system matches the certified assembly, including the design number, hourly rating, cable type, supports, splices and other required components.
Product iQ is available at no cost to use but requires a one-time registration. Fire-resistive cable systems can be found in Product iQ under the following category control numbers (CCNs):
Code authorities can also search directly by a manufacturer's UL Solutions file number to access the associated certification information.
Fire-resistive cable systems are certified as complete assemblies, evaluated across fire endurance, hose stream and mechanical conditions, and — for data and communication cables — held to defined signal performance under those same conditions. That certification record is searchable in Product iQ.
