Fires can’t always be prevented, but with a plan in place, fires are more easily contained and people can be kept safer. The same principle applies when choosing cables for your communication network. Some cable materials can pose real threats when ignited, especially if the fire is in an enclosed space where evacuation is not an option. For this reason, cable flammability ratings were developed. Here, we’ll take a look at what these ratings mean and how to use them to keep yourself safe and keep your communications equipment from going up in flames.
Most commercially available cable assemblies have an outer jacket made from polyvinyl chloride (PVC). PVC is durable and flexible, making it a great option for many applications. But for all of its benefits, PVC has some serious shortcomings. In a fire, PVC cables can act as a flame accelerant and emit dangerous, toxic gases. Fortunately, there are cable jacket materials on the market that are less-flammable and much safer. These are especially good options for installations in enclosed spaces such as ships, aircraft, submarines, trains and other vehicles.
General Purpose (CM, CMG, CMx)
These cables comply with UL-1582. They will burn but they partially self-extinguish. These are often used for workstation cables and patch cords, but are not for use between building floors or in air plenum spaces.
Riser-rated (CMR)
Riser-rated cables are UL-1666 compliant and are designated for use in vertical tray applications such as cable runs between floors, through cable risers or in elevator shafts. In order for a cable to be Riser-rated, it must be able to self-extinguish.
Plenum-rated (CMP)
Plenum-rated cables comply with NFPA-262 and UL-910. They are the only cables permitted in spaces identified as air plenums, such as raised flooring systems and air handling ducts. Cables designated as plenum-rated are able to self-extinguish and will not re-ignite.
Low-Smoke Zero-Halogen (LSZH)
As the name states, these cables produce low-smoke and zero halogen, plus they are self-extinguishing. Because they significantly reduce the amount of smoke and eliminate harmful halogen from being emitted, they are used in enclosed spaces where smoke and fumes can injure people and equipment.
