Brief Discussion on Cable Safety Grade of Cabling Specification

UL divides the wiring used by voice and data systems into "communications cabling and cabling," abbreviated CM. This category provides a variety of security levels for specific applications that are used to verify the quality of cable jackets. See specifics below:

CMP: Fill-level communication cable, this is the highest cable safety rating, it has perfect flame-retardant ability and emits low smoke and toxins. According to the definition of UL, under the condition that the fan is forced to intensively burn, a bundle of CMP cables must extinguish itself within less than 5 meters of the combustion spread. The CMP cable uses Teflo-based chemicals to prevent the combustion from spreading and to minimize the emission of smoke and toxins. This adds a lot of cost compared to lower UL grade cables. CMP grade cables are used to vent air back into the building where the cable is laid. In the event of a fire, the building will not be full of smoke or dangerous toxins emitted by the cables. The air return network is widely used in the United States, but it is used less frequently in other parts of the world. CMP grade cables must undergo a rigorous burn test: UL 910 - "Flame Propagation and Smoke Density Value Test"

CMR: trunk level communication cable. This is the second-ranked cable. It has perfect flame-retardant capabilities, but it does not test for emitted aerosol toxins. In addition to CMP and cables, CMR cables and all other communication cables use halide-based chemicals, such as chlorine, to prevent combustion and diffusion. By definition, a bundle of CMR cables must self-extinguish within less than 5 meters of the combustion spread under forced fan combustion conditions. CMR cable jackets are generally made of a type of PVC that emits chlorine gas in the combustion chamber. Chlorine depletes the oxygen in the air and extinguishes the flame. CMR grade cables are widely used in mainline applications where the ventilation system is physically separated from the wiring system. This is very common in Asia and Australia. CMR grade cables must pass a intensive flame test: UL1666 - "Vertical cable flame propagation height test for installation into the centre."

Low Smoke Zero Halogen (LSZH) : Another level of safety used in the cabling industry is the Low Smoke Zero Halogen (LSZH) cable. This safety level is divided by ISO/IEC standards and is widely used in Europe. The LSZH grade, like the UL CMP grade, tests the flame retardant ability and emitted gas. As the name implies, the burning LSZH will not emit halide gas, and the emitted smoke is very low. The LSZH grade cable can be used for copper and fiber optic communications cables, and its structure is similar to that of UL grade cables.

CM/CMG: General communication wiring. This is common in the horizontal alignment of the building and they are usually divided into smaller bundles than CMR grade cables. The CM/CMG grade cable uses a halide-based chemistry for timelines. By definition, in a small bundle of cables, the CM/CMG cable must self-extinguish within less than 5 meters of the combustion spread. The flame did not use a fan to force combustion. CM/CMG grade cable jackets are usually made of some type of PVC and emit chlorine in the combustion chamber. CM/CMG grade cables are commonly used in horizontal cabling in the United Kingdom, Asia, and Australia. CM/CMG grade cables must pass the CSA FT-4 "Vertical Burn Test".

CMX: Residential communications wiring. This type of cable is limited to other small applications where there is a very small number of residential or telecommunication cables in use. These applications typically use only one cable. CMX grade tools cannot be used for bundled cable applications. CMX grade cable must pass UL VW1 combustion test.