CM-rated cable, standing for Communications Multipurpose, represents the minimum standard for Ethernet cables specifically permitted for installation within the walls of single-story commercial buildings.
Understanding the CM Rating
The CM rating is a crucial classification for network cables, particularly those used for Ethernet. This rating is determined by how the cable performs in standardized flammability tests.
According to industry standards, a cable must pass a specific flammability test to receive the CM rating. This test assesses how easily the flame spreads along the cable jacket, ensuring it meets minimum safety requirements for certain installation environments.
Key Characteristics of CM-Rated Cable
Based on the standard definition, here are the primary characteristics of CM-rated cable:
- Meaning: Communications Multipurpose
- Minimum Standard: Represents the baseline flammability requirement for certain installations.
- Flammability Test: Must pass a specific test to limit flame spread.
- Typical Application: Minimum standard for Ethernet cables installed within the walls of single-story commercial buildings.
Where CM-Rated Cables Are Used
The primary application area for CM-rated cables, as defined, is confined spaces like inside the walls of single-story commercial structures.
While CM is a common rating, it's important to note that it has lower flammability resistance compared to other ratings like CMR (Riser) or CMP (Plenum), which are required for installations involving vertical runs through floors or within air handling spaces, respectively. Therefore, CM-rated cable should only be used in environments where its specific rating is permitted by local building codes. Using a cable with an inadequate rating can pose a significant fire safety risk.
