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CAT-5 Plenum Versus Standard Cable

Question: I am adding a number of circuits to my low voltage cabling in my 3 story townhouse. I will be installing a conduit that runs from the bottom floor utility room to the second story and then proceeding on to the third story. I have been told that I should use riser cable. It is much more expensive than the standard CAT 5. Do I need to use riser cable?

Answer: Riser cable or plenum cable as it is sometimes called is really designed to be installed in hot air shafts. It has a layer of heat resistant insulation surrounding the internal cables. As you are running the CAT 5 cable in a conduit there is no need to use CAT-5 cable that is specified for riser or plenum installation.

When running the CAT-5 cable in the conduit, pay special attention to the bend radius. You should use conduit elbows, as shown in Figure 1, rather than "L" fittings, as shown in Figure 2. The minimum bend radius for CAT-5 cable is 4 times its diameter.

conduit elbow fitting

Figure 1 - Conduit elbow fitting

conduit "L" fitting

Figure 2 - Conduit "L" fitting