What Type of Cabling Should You Use in the Area Above the Ceiling or Below the Subflooring?

When running cables in the areas above the ceiling or below the subflooring, which are often referred to as plenum spaces, it's important to use the correct type of cabling to comply with building codes and safety regulations. These spaces can have increased airflow, and in the event of a fire, cabling without proper insulation could spread toxic fumes or contribute to the fire’s intensity.

Here are the types of cabling you should use:

Plenum-rated Cabling

Plenum-rated cabling is designed specifically for use in plenum spaces. It has a fire-retardant jacket made from materials that emit fewer toxic fumes when burned.

Cat5e/Cat6/Cat6a plenum-rated Ethernet cables are commonly used for networking in these areas.

Fiber optic cables also come in plenum-rated varieties and are used for high-speed data connections.

Coaxial cables can be plenum-rated for use in video and RF (radio frequency) applications.

Riser-rated Cabling

Riser-rated cables are designed to prevent the spread of fire between floors through riser spaces. They can be used in vertical runs but are not recommended for horizontal plenum spaces.

Shielded Cabling

In environments with potential electromagnetic interference (EMI), using shielded twisted pair (STP) cables can help mitigate such interferences.

Non-plenum Cabling

Non-plenum cabling is cheaper but should not be used in plenum spaces because it does not have the fire-resistant properties required for those areas. It's typically used in non-plenum areas where the cable runs are enclosed in conduit or raceways.

Additional Considerations:

Local Codes and Regulations: Always check the local building codes and fire regulations before installing any cabling. These codes will dictate the exact requirements for cabling in plenum spaces.

Cable Supports: Use appropriate cable supports and pathways designed for use in plenum spaces.

Installation: Ensure that cabling is installed by qualified personnel following industry standards such as those set by the National Electrical Code (NEC) in the United States.

For areas above the ceiling or below subflooring that are plenum spaces, you should use plenum-rated cabling. Always check local building codes for the specific requirements for your area, and if in doubt, consult with a professional or the Authority Having Jurisdiction (AHJ).