Here’s a quick guide—learn about the types of fire-resistant cables in just one minute!-Qinshan

Here’s a quick guide—learn about the types of fire-resistant cables in just one minute!

Nov 28,2022

　　What are the types of fire-resistant cables? Let’s take a brief look at them together below. The UL flame-retardant standards primarily include several grades: CM, CMG, and CMX. 1) The enhanced-grade—CMP grade (Plenum Flame Test/Steiner Tunnel Test)—is the highest-level cable required under the UL fire-resistance standards (Plenum Cable), and it complies with the UL910 safety standard. The test involves placing multiple samples on horizontal air ducts within an installation and exposing them to a 87.9-kilowatt gas Bunsen burner (300,000 BTU/hr) for 20 minutes. The acceptance criterion for fire-resistant cables is that the flame must not propagate beyond 5 feet from the front of the gas Bunsen burner flame. The peak optical density shall not exceed 0.5, and the average optical density shall not exceed 0.15. Typically, CMP cables are installed in pressurized air return systems used in ventilation ducts or air-handling equipment, and they are recognized in both Canada and the United States. FEP/FLENUM materials that meet the UL910 standard exhibit superior flame-retardant performance and produce lower smoke concentrations during combustion compared to low-smoke, halogen-free materials that comply with IEC60332-1 and IEC60332-3 standards.

　　2) Riser Cable—CMR Grade (Vertical Flame Test—Riser Cable Planetary Test): This is a UL-standard enterprise-grade cable (Riser Cable), with safety standards specified by UL1666. The test procedure involves installing multiple samples on a simulated vertical axis and exposing them to a prescribed 154.5-kilowatt gas Bunsen burner (527,500 BTU/hr) for 30 minutes. The pass criterion is that the flame must not propagate beyond the ceiling of the room, which is 12 feet high. Riser-grade cables have no smoke density requirements and are typically used for both vertical and horizontal wiring within a single floor. 3) Commercial Cable—CM Grade (Vertical Flame Test—Vertical Tray Flame Test): This is a commercial cable conforming to UL standards, with safety standards specified by UL1581. The test procedure requires placing multiple fire-resistant cable samples on an 8-foot-high vertical base and subjecting them to a prescribed 20-kilowatt ribbon-type spray flame (70,000 BTU/hr) for 20 minutes. The pass criterion is that the flame must not spread beyond the top of the fire-resistant cable and must self-extinguish without further propagation. UL1581 is similar to IEC60332-3C, but differs in the number of cable cores wrapped around the cable. Commercial cables have no smoke density requirements and are typically used only for horizontal routing within the same floor; they are not suitable for vertical cabling between different floors.

　　4) General—CMG Grade (Vertical Tray Flame Test): This is a general-purpose cable that complies with UL standards, and its applicable safety standard is UL1581. The testing conditions for the Commercial Grade and Standard Grade are similar to those recognized in Canada and the United States. General-grade cables do not have specific smoke-density requirements and are typically suitable only for horizontal routing within the same floor level; they are not appropriate for vertical cabling between floors. 5) Home—CMX Grade (Vertical Wire Flame Test): This is a home-grade cable that conforms to UL standards, with the applicable safety standards being UL1581 and VW-1. The test procedure requires holding the fire-resistant cable sample vertically and exposing it to an experimental flame spray (3000 tu/hr) for 15 seconds, followed by a 15-second pause. This cycle is repeated five times. The pass criteria are as follows: the residual flame duration must not exceed 60 seconds; the sample must not burn more than 25% of its original length; and surgical cotton placed on the floor must not ignite upon falling debris. UL1581-VW-1 is similar to IEC60332-1, but the burning durations differ. This grade does not have any smoke or toxicity specifications and is intended solely for use in single-cable installations in residential or small-office systems. Such cables must not be bundled together and must always be installed using conduit.

Installation, Transportation, and Storage Considerations for Fire-Resistant Cables

Here’s a quick, no-nonsense guide—get an overview of the development trends in fire-resistant cables in just one minute!

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