Electrical Metallic Tubing (EMT), also commonly called thin-wall, is a listed steel raceway of circular cross section, which is unthreaded, and nominally 10′ long. 20′ lengths are also available.
Covered by Article 358 of the NEC, UL797, CSA C22.2 No.83.1 and ANSI C80.3, EMT is available in trade sizes 1/2″ through 4″. The outside and inside are both galvanized for corrosion protection.
EMT is installed by use of set-screw or compression-type couplings and connectors.