Plenum cables are constructed with low smoke coating such as Teflon FEP material. The coating does not smoke nearly as much as other plastics and gives zero flame spread. Plenum (CMP) cable can withstand up to 400 degrees. Plenum cable has the highest fire resistance rating compared to all other jacket materials. When you’re planning to run cable through any building, the first thing to consider is exactly where do you want to run your wires? Plenum space is above the ceiling or below floors that are used for air circulation. These areas can cause major issues should there be a fire due to the high oxygen and lack of fire barriers in plenum spaces.