This was dreamed up as I was playing with the concept of a homemade auto transfer switch. It monitors the 2 hots that enter the service. If both hot wires are energized the green led comes on indicating no problems. The red led indicates the loss of a phase or all power. The green led can be used as an arduino input to control the transfer switch, alarm, ow what not. With this detection circuit on all power sources it provides more information on what's ready and what's not.
