When installed in ducts and plenums, what type of communications cables must be used?

When it involves the installation of communications cables in ducts and plenums, the most appropriate choice is the type approved for this specific environment, which is CMP (Communications Multipurpose Plenum).

Plenum spaces are areas where air circulates for heating, ventilation, and air conditioning systems. Due to the potential risks posed by fire in these spaces, the National Fire Protection Association (NFPA) and Underwriters Laboratories (UL) specify that cables installed in such environments must have low smoke production and flame-resistant characteristics.

CMP cables are specifically designed for use in plenum spaces, as they meet the stringent fire safety standards necessary to minimize smoke and flame spread in case of a fire. This makes them the safest option for installations in these areas, reducing potential hazards for both people and property.

In contrast, CM (Communications Multipurpose) and CMG (Communications Multipurpose General) cables are not rated for use in plenum spaces, and CMX (Communications Multipurpose Riser) cables are typically used for vertical riser applications. Their fire resistance ratings do not meet the stringent requirements for installation in plenum areas, which is why CMP is the correct choice in this scenario.