What the Letters Mean
UL cable ratings define how a cable behaves in a fire and where it may be installed:
- CM (Communications) — general-purpose, lowest rating
- CMR (Riser) — for vertical runs between floors; resists flame spread
- CMP (Plenum) — for air-handling spaces; lowest smoke, self-extinguishing
Which Do You Need?
Use CMP whenever the cable runs through plenum (HVAC) spaces — it's often required by code. CMR is the default for risers. Specifying the wrong rating can fail inspection. Tell us your environment and we'll match the rating.
