Intermediate Metal Conduit (IMC)

IMC was developed in the 1970s as a thin-wall alternative to rigid metal conduit (RMC) that weighs about one-third less. IMC ships with either a straight-tapped or integral coupling. It features a galvanized OD and corrosion-resistant ID coating.

Electrical Code Compliance

IMC is covered under Article 342 in the NEC®.

IMC Sizing

IMC is available in trade sizes 1/2 through 4, and 10′ lengths. Threads on the uncoupled end are covered by industry color-coded thread protectors to protect the threads, keep them clean and sharp, and aid in trade size recognition. Thread protectors for trade sizes 1, 2, 3 and 4 are color-coded orange; trade sizes 1/2, 1 1/2, 2 1/2 and 3 1/2 are yellow; and trade sizes 3/4 and 1 1/4 are green.

Using IMC as a Substitute for RMC

IMC is interchangeable with galvanized RMC. Both have threads with a 3/4-inch-per-foot taper, use the same couplings and fittings, have the same support requirements and are permitted to be used in the same locations.

IMC Weights and Dimensions

Trade Size DesignatorNominal Wt. per 100 Ft. (30.5m)Nominal Outside DiameterNominal Wall ThicknessQuantity in Primary BundleMaster Bundles
QuantityApprox. Wt.Volume
U.S.Metriclb.kgin.mmin.mmft.mft.mmlb.kgcu ft.cu m
1/2166228.10.81520.70.0781.9710030.5350010672170984.326.40.7
3/4218438.11.02926.10.0832.15015.225007622100952.533.50.9
127119541.2932.80.0932.355015.217005182023917.632.10.9
1 1/43515871.71.63841.60.0952.41--13504112133967.534.71
1 1/241194881.88347.80.12.54--11003352134968351
253256116.12.3659.90.1052.67--800244204892930.90.9
2 1/2634412002.85772.60.153.81--3701131632740.333.59
378543246.33.47688.30.153.81--300911629738.938.31.1
3 1/291629285.33.971100.70.153.81--240731510684.941.71.2
4103700317.54.466113.40.153.81--24073168076248.61.4