In order to run two 3/4" conduits in/out from 2"x4" back box of duplex receptacles, do we need to extend the size of back box?
Those are easily overfilled with the capacity of just a single 1/2 inch raceway entry as well.They do make deep handy boxes that are 2 1/8" deep. Again as others have said it has nothing to do with the conduit size but rather on the number of conductors.