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Electrical metallic tubing (EMT), also called thin-wall, is a listed steel unthreaded raceway of circular cross section. Available nominal lengths are sold as 10' long, however, 20' lengths are also available. Covered by Article 358 of the National Electrical Code (NEC), EMT is available in trade sizes 1/2" through 4". The outside diameter is galvanized (aka zinc plated) for corrosion protection and the inside diameter has an approved corrosion-resistant organic coating. EMT is installed by use of a set-screw or a compression-type coupling and connectors. It is permitted to have an integral coupling comprised of an expanded, “belled” shape tube on one end with set screws as shown in the middle photo above or with a Kwik-Fit Compression Coupling as shown in the bottom photo above. EMT with integral couplings is available in trade sizes 1-1/4" through 4".
