A power supply apparatus 10 with circuit load sensor provides an extension cord 20 having first and second ends extending from an enclosure 30. Within the enclosure, a power supply indicator circuit 40 lights an LED in response to the plug of the extension cord being inserted into a live outlet. Also within the enclosure, a power consumption indicator circuit 60 lights an LED in response to consumption of power by a load plugged into the socket of the extension cord. A nominal voltage drop across a TRIAC 70, carried in-line with the neutral conductor within the enclosure, triggers the power consumption indicator circuit when the load draws current.