Communications Cable Ratings
When purchasing our Ethernet cables (Cat5e, Cat6, Cat6a), you may come across the following markings located on the cable or product listings: CM, CMR, CMG, CMP, CMX. These are cable markings that are used by the National Electrical Code or NFPA 70 when referring to their standards. In this post, we will be doing a quick overview of each of these common markings.
1. CM rated cables meet the UL 1685 standard and are suitable for general use in residential / commercial applications. These are typically found in everyday Ethernet stranded cables you see running from a computer to a router / switch / wall plate. CM rated cables can be used in-wall and used in non-plenum / non-riser environments. They meet the vertical-tray flame tests under UL 1685 for electrical and optical fiber cables.
2. CMG rated cables are tested to the CSA FT4 vertical-tray flame test in the UL 1685 standard and are also suitable for general use applications.
3. CMR rated cables or riser rated cables ("R" denotes the riser) are used between floors through risers or vertical shafts in non-plenum areas. These are typically found in our solid wire Cat5e, Cat6, and Cat6a bulk cables. CMR rated cables meet the UL 1666 standard - testing of flame propagation height for cables installed in vertical shafts.
4. CMP rated cables or plenum rated cables ("P" denotes the plenum) meet strict safety fire test standards set by the NFPA 262 and UL 910 - testing for flame propagation and smoke density. These types of cables are used in plenum spaces of buildings - air space above a drop ceiling or below a raised floor.
5. CMX rated cables meet UL 1581 and are typically used if the cable is enclosed in a raceway / combustible tubing, in conspicuous space where the length does not exceed 10 feet, or when the cable diameter is less than 0.25 inches (Section 800.154(E) NEC). These types of cables can also be marked for outdoor use. VW-1 flame test in accordance with UL 1581.