Abstract: A power indicator for extension cords has a male connector at a first end and a female receptacle at a second end, a transformer interposed between, and electrically coupled to, the male connector and female receptacle, the transformer configured to read a load on a circuit and illuminate at least one LED when the load is above a predetermined threshold, indicating that a block heater or other device is drawing power. When connected to an engine block heater, a user can confirm that the block heater is drawing power by the indication of the LED.