What mark is given to riser-rated data cables under the US National Electrical Code (NEC)?

Riser-rated data cables are designated with the marking CMR under the US National Electrical Code (NEC). This designation indicates that the cables are suitable for vertical spaces between floors and can be used in areas where there is a riser, such as conduits or shafts. Riser-rated cables are built to reduce the risk of fire spreading between floors and are made with a fire-resistant jacket that can limit the spread of flames.

The CMR designation is essential for compliance with building codes that require specific types of cabling in certain environments. This makes them more suitable for vertical installations compared to other cable ratings that are not specifically designed for riser applications. Understanding these cable ratings helps ensure that installations are safe and meet necessary regulatory standards.