Riser cable (CMR) / backbone cable is a cable that is run between floors in non-plenum areas. The fire requirements on riser cables are not as strict as the requirements on Plenum cables (CMP). There are both Cat5e riser (CMR) cables and Cat6 riser (CMR) cables.

A plenum cable can always replace a riser cable, but a riser cable cannot replace a plenum cable in plenum spaces. Twisted-pair, coaxial, HDMI, and DVI versions of cable are made in plenum and riser versions.

Riser Cables

The riser cable gets its name from its function – it rises between the floors of a multi-story structure/building. A riser cable is the primary conduit of a building’s distribution system. It carries voice, data, and video into the different spaces and levels of a building from the service entrance point.

Backbone System

A riser cable is a part of a building’s backbone system. Other components of the backbone system include cable pathways, telecommunications closets, equipment rooms, and related hardware, as well as support facilities.

Planning for the Future

Since cable requirements are different for the various services, planning for future use needs can be tricky. Especially since future uses of the backbone wiring can range from the predictable to the entirely unknown. Due to this unknown variable, it is typically suggested to separate riser systems for different applications (such as voice and data) that follow parallel routes through pathways, closets, and equipment rooms.