Why CMP Verification Matters
CMP cable is used in air-handling spaces where flame spread and smoke performance requirements are stricter than standard communications cable applications.
Before the pull, installers should verify that cable marked CMP is properly listed and that the package and cable jacket markings match the certification information.
If the price seems unusually low, take another look before installation. Check the UL listing, file number, CMP rating, package certification mark, and cable jacket print. Price alone does not confirm a plenum rating.
Check the UL Listing
Start with the package label and certification information.
Look for the UL file number, CMP rating, and certification mark on the carton. ICC bulk cable is UL Listed under File Number E320548 for multiple communications cable ratings, including CMP plenum and CMR riser cable.
The UL certificate can also be used as a verification point before installation.
Check the Cable Jacket
The cable itself should also carry the proper markings.
Check the jacket print for the UL file number, UL mark, and CMP rating. Verifying the cable jacket helps confirm that the cable being installed matches the package and listing information.
Why Plenum Spaces Matter
A plenum space can be part of a building’s return-air system.
When the ceiling space is used for return air, air moves through the open plenum before returning to the HVAC system. Smoke can move through that same space.
Because communications cable may be installed in the plenum, CMP cable is required to meet stricter flame and smoke requirements for these applications.
Where CMP Cable May Be Used
Common plenum applications include:
- Above suspended ceilings used for return air
- Below raised floors used as air-handling spaces
- Other environmental air spaces where CMP-rated cable is required by code
The installation environment should always be reviewed before selecting the cable rating.
Be Ready for Inspection
Using properly listed and correctly marked cable helps reduce the risk of inspection issues, replacement pulls, rework, and job delays.
Keep the certification information available and verify the cable before installation so the product markings, package label, and UL listing all match.