I've found a series of ethernet cables running through various exposed* areas in my house and I'm wondering how to tell if they are plenum grade.
*exposed areas are running through duct work and along the base board from the duct vent.
if i am getting you properly other wise tell me
Look for CMP(means Communications Plenum Cable) ,CL3P(Shielded Multi-Conductor Plenum Security Cable) , or CL2P(Class 2 plenum cable ) marked on the cable.
Plenum cable is covered with a fire proof plastic layer of either a low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer (FEP).
It may have a "CMP" designation on it. If it has a "CM" or "CMR" it is not plenum rated.