I am building a machine that uses a 12 volt DC motor. I was looking to use a class II (double insulated) power supply to go from 120 v AC to 12 v DC. The power supply would be located inside the electronic circuit enclosure. The power supply doesn't have a ground terminal on the AC side. Since the power supply is inside the enclosure, do I need to use a 3 wire power cord and connect the ground wire to the metal enclosure? I would think it would be possible to have a wire come loose inside the enclosure and potentially shock someone without a ground connection.