Copper NMB Romex® Electrical Cable Information

Romex and MC cable are both standard items in the electrical wire industry. While both these cables look quite different they can be used in some of the same applications.

Romex® wire is used as an indoor only cable because of the bare copper ground wire. All of our Romex® is made with THHN THWN wire (Thermoplastic High heat and Water resistant Nylon coated) which can be used outdoors. However the thin Romex® jacket can not stop water or moisture from penetrating and coming in contact with the uninsulated ground wire. As a result Romex® can only be used indoors.

MC cable is made with THHN wire as well and an insulated ground wire which allows it to be used in conduit and outdoors. You can see the difference in the two pictures below: MC cable has all 3 wires insulated while Romex® has one bare wire. Type MC (Metal Clad) also has the aluminum metal clad jacket instead of the thin PVC jacket on Romex® cable. It allows for much easier stripping and installation in the electrical field.

UFB cable is the next step up from these two cables which is known as the underground cable. It comes in sizes up to 6 awg and has a tough outer jacket for added protection underground.


Romex® Wire MC Cable