One of the most recognized authorities on cabling safety is UNDERwriters Laboratories (UL), a non-profit organization dedicated to establishing and maintaining safety standards for a wide range of industries. UL provides a wide range of quality inspection services to the cabling industry. Its services include: inclusion in the UL list. Verify wiring and associated hardware safety levels.
UL test. To verify the transmission performance and safety level of cabling according to the performance specification specified in TIA/EIA cabling standards; And through the quality assurance monitoring and factory surprise inspection, regular inspection.
UL communication wiring
UL divides the wiring used for voice and data systems into "communication wiring and cables", abbreviated CM. In this category, a variety of safety levels are provided for specific applications to check the quality of cable jacket, as shown below:
CMP: Packed grade communication cable, the highest cable safety rating, has perfect flame retardancy and emits very little smoke and toxins. According to UL definition, a bundle of CMP cables must self-extinguish within 5 meters of the combustion diffusion under fan-forced intensive combustion conditions. CMP cables use Teflo based chemicals to prevent combustion from spreading and minimize the smoke and toxins emitted. This adds a significant amount of cost compared to lower UL grade cables. CMP class cables are used to ventilate the return air into buildings where cables are laid. In the event of a fire, the building will not be filled with large amounts of smoke or dangerous toxins from cables. This return mesh is widely used in the United States, but less so in other parts of the world. CMP class cables must undergo a rigorous fire test: ULArray10- "Flame Propagation and smoke density Value Test"
CMR: Trunk class communication cable. This is the second highest grade cable. It has perfect flame retardant capability, but there is no test for smoke and toxin emission. In addition to CMP and cables, CMR cables and all other communication cables use halide based chemicals, such as chlorine, to prevent combustion from spreading. By definition, a bundle of CMR cables must extinguish themselves within 5 meters of the combustion diffusion under fan forced combustion conditions. The CMR cable jacket is typically made of a type of PVC that emits chlorine in the combustion chamber, which depletes the air of oxygen and extinguish the flame. CMR class cables are widely used in mains applications where ventilation systems are physically separated from wiring systems. This is very common in Asia and Australia. CMR class cables must undergo intensive flame test: UL1666- "Flame Propagation Height test for cables to medium vertical installation"
CM/CMG: General purpose communication wiring. This is common in the horizontal wiring of buildings, which are usually broken up into smaller bundles than CMR grade cables. The CM/CMG class cable USES halide based chemicals. By definition, in a small bundle of cables, the CM/CMG cable must self-extinguish within 5 meters of the combustion diffusion. The flame does not use a fan for forced combustion. CM/CMG class cable jackets are usually made of some type of PVC and emit chlorine in the combustion chamber. CM/CMG class cables are commonly used in horizontal lines in the United Kingdom, Asia and Australia. CM/CMG class cables must undergo CSAFT-4 "Vertical combustion test"
CMX: Residential communication wiring. This cable is limited to residential or other small applications where a very small number of communication cables are used, and these applications are generally limited to a single cable. CMX level tools cannot be used for baled cable applications. CMX class cables must undergo ULVW1 combustion test
Low smoke zero halogen (LSZH)
Another level of safety used in the cabling industry is low smoke zero halogen (LSZH) cables. This level of safety is defined by ISO/IEC standards and is widely used in Europe.
The LSZH class, like the ULCMP class, tests flame retardancy and emission of gases. As the name suggests, burning LSZH does not emit halide gas and emits very low smoke. LSZH class cables can be used for copper and fiber optic communication cables and are similar in structure to UL class cables.