A power distribution unit is connected to a three-phase electric power source having three phase wires with different phases, and includes a socket and a switch. The socket has a first socket terminal connected to one of the phase wires, and a second socket terminal. The switch includes a first switch terminal connected to another one of the phase wires, a second switch terminal connected to a neutral, and a third switch terminal connected to the second socket terminal. By selectively connecting the third and the first switch terminals, or connecting the third and the second switch terminals, a line-to-neutral voltage or a line-to-line voltage from the three-phase electric power source is outputted by the socket.