OREANDA-NEWS. February 17, 2011. Rigid Metal Conduit (RMC), also called Rigid Galvanized Conduit (RGC), is the heaviest-weight and thickest-wall steel conduit. Where galvanized by the hot-dip process, it has a coating of zinc on both the inside and outside surfaces, reported the press-centre of RMC.

Rigid Metal Conduit can also have a combination of zinc and organic coatings, or a nonmetallic coating (such as PVC). Supplementary coatings can be applied for applications in extremely corrosive locations or atmospheres. Rigid is a threaded product and is delivered with a standard straight tapped or an integral type coupling.

Threads on the uncoupled end are covered by industry color-coded thread protectors. Rigid Metal Conduit is available in trade sizes 1/2- to 6-inch diameter in a nominal length of 10-feet. Rigid Steel Conduit can be used indoors, outdoors, underground and in both concealed and exposed locations.

RMC is covered by 2005 NEC Article 344.