CMR, or riser-rated, cables are designed for vertical runs between floors and other in-wall riser applications, while plenum-rated cables use lower-smoke, lower-flame materials for air-handling spaces such as drop ceilings and raised floors. General-purpose cables are intended for standard spaces that do not require riser or plenum ratings, so select the cable type based on the installation path and applicable local codes.

Choose the conductor gauge based on the system’s power and distance requirements, with 18 AWG supporting applications that call for a larger conductor and 22 AWG fitting many lower-power security, alarm, intercom, and control connections. Select the conductor count to match the number of circuits or signal pairs needed, then choose a cable length that covers the run with practical routing room while limiting splices and confirming that the CMR rating suits the in-wall or riser installation.

Choose solid CMR cable for fixed, in-wall runs where the cable will remain in place and consistent conductor geometry supports terminations. Choose stranded CMR cable for security, alarm, intercom, or control wiring that needs more flexibility, such as connections to devices, panels, or equipment that may move during installation or service.

Before installing CMR cables, review applicable electrical, building, and fire codes, confirm the cable jacket carries the required CMR or riser marking, and verify that the planned wall or riser pathway suits the cable rating. Also check requirements for cable support, bend radius, separation from power wiring, termination, and whether a plenum-rated cable is needed for air-handling spaces.