Electrical Metallic Tubing — EMT (ferrous metal). Also commonly called thin-wall, EMT is a listed steel raceway of circular cross section, which is unthreaded and normally 10 feet long . The outside corrosion protection is zinc-based, and the inside features an approved corrosion-resistant organic coating. EMT with integral couplings is available in trade sizes 2½ through 4.
Steel Conduit Basics
Electrical metallic tubing is unthreaded and features a zinc-based outer coating and corrosion-resistant organic inner coating.
EMT is installed by use of setscrew, identation or compression-type couplings and connectors. It can have an integral coupling that comprises an expanded, “bell” shaped tube on one end with setscrews .
In addition to standard RMC, IMC, and EMT, PVC-coated steel conduit (PVC) is also available in one of three types. Couplings are supplied separately.