CMR (Communications Multipurpose Cable, Riser) and CMP (Communications Multipurpose Cable, Plenum) cables are network cabling used in buildings. They are your CAT5e, CAT6, CAT6A, and CAT8 cables, rated for their use in the building. CMP and CMR have different specifications and uses based on the environments in which they can be safely installed.

What are CM cables?

CM cables are "Communications Multipurpose," a fire-resistant rating outlined in article 800 of the NEC. This communication cable standard coincides with UL 1581 and CSA FT1 flame tests. It is used in standard residential settings on the same floor.

What are CMR cables?

CMR cables (Communications Multipurpose Riser) are designed for use in riser applications, which typically include communications in in-wall vertical runs between the floors of a building through riser shafts. These cables are engineered to prevent the spread of fire from one floor to another and are more flame-resistant than regular PVC cables. However, they are unsuitable for plenum spaces where air circulation can cause fires to spread more quickly.

They coincide with the UL 1666 and CSA FT4 standards.

CMR cables are insulated with either PVC or PE.

What are CMP cables?

CMP cables (Communications Multipurpose Plenum), on the other hand, are made for use in plenum spaces or drop ceilings of buildings. Plenum spaces are the parts of the building through which air circulation for heating and air conditioning systems is facilitated. These spaces often have higher oxygen levels, which can accelerate fire. CMP cables are made of materials that emit low smoke and low toxicity when exposed to fire, so they are safer for use in these areas.

CMP has either a low-smoke PVC or FEP jacket.

They fit UL 910 plenum test and CSA FT6. Any CAT cable can be CMR or CMP.

Key differences between CMP and CMR

• CMP cables have higher fire resistance than CMR cables. CMP cables must resist burning and not emit harmful fumes when they do catch fire.
• CMP cables are suitable for plenum spaces due to their superior fire-retardant properties, while CMR cables are used in vertical risers or other non-plenum areas.
• CMP cables are generally more expensive than CMR cables due to their advanced safety features.
• CMP cables can be used in riser applications, but CMR cables cannot be used in plenum applications.
• CMP cables are generally required in any space used for air circulation for HVAC systems, while CMR cables are restricted to areas that do not handle environmental air.