When running wires underground through PVC conduit to feed a garage, is THHN or THWN the proper type to use? Suppose a garage is to be wired with a subpanel fed from the house by a 40-amp 240V breaker. They would use each a red, white, black, and green #8 AWG copper conductor, but what type of insulation? Since the conduit is dry when placed in the ground, and glued with PVC cement so that water can never enter it, would that still be considered a wet location?
Also, suppose a 3-way switch was to be added for the outside garage light to be operated from the house as well. A red, black, and blue #14 AWG would each need to be pulled through the conduit as well. What is the minimum size conduit that can hold four #8 conductors and three #14 conductors?