What is conduitin construction?

EMT (electrical metallic tubing) covers most interior dry locations because it is light and fast to install. Rigid metal conduit (RMC) is threaded heavy wall pipe used where runs need maximum physical protection, with IMC as a lighter intermediate option. PVC handles underground and corrosive locations, and flexible metal conduit or liquidtight makes the final connection to motors and vibrating equipment. The Division 26 raceway spec maps each type to its permitted locations.

Branch circuit plans show devices and homerun arrows, not routed lines, so the estimator measures a realistic ceiling path from the panel to each circuit, adds vertical drops at the panel and at the devices, and applies the result per homerun. Many estimators carry an average lf per circuit by building type and document it as an assumption. The key is writing the routing logic down so a reviewer can trace the footage.

Conductor fill. The NEC limits the conductors in a conduit to 40 percent of its internal cross section when three or more are installed, so the count and gauge of the wires set the minimum trade size. Feeder conduit sizes are stated on the one-line diagram and feeder schedule, while branch run sizing is usually left to the contractor, which is exactly where takeoff assumptions about 1/2 in versus 3/4 in show up in the price.