A.Master electrician Rex Cauldwell responds: For practical purposes, the maximum number of 12-gauge THHN conductors for a 3/4-inch EMT conduit is nine.

The answer would be different for another type of conduit (for example, ENT), or if the conductor had a different insulation type or different outside diameter. Although the NEC allows up to 16 current-carrying THHN conductors in such a conduit, it also requires that for any number of conductors over three, you have to derate the capacity of the...

or Register to read the full article.