What Does Cm Rated Cable Mean

When installing ethernet cable in walls or ceilings you may encounter terms like cm cmr cmp or some others like pvc and lszh.

What does cm rated cable mean.

Among all these terms cm cmr and cmp are the most common ethernet cable ratings specified by the national electric code nec. In the case of cm the standard outlines general use or use in cases where the fire code does not place any restrictions on cable type. This is the next step up. A cmr rating means the cable can be used in the risers of commercial buildings because they limit the spread of flames better than cables in the cl cm family.

Another common cable rating is cm which denotes communications cable such as cat 5e or cat 6 networking cable. When shopping for cables you may notice they re nearly always classified as cat 5 cat6e or something similar. Cat simply stands for category. Cl2 and cl3 cable doesn t reduce smoke or gases but minimize the possibility of shock.

These are used for regular networking from room to room as long as the cable does not need to pass through an air duct. Cmr cable often called riser rated cable is constructed to prevent fires from spreading floor to floor in vertical installations. Often this type of cable meant for home usage will carry an x suffix signifying that it is intended for use in buildings where the cable is enclosed in a non combustible conduit. They can be installed anywhere except plenums.

Do you know what these terms really mean and which one does your project actually need.