GFCI tester with adjustable hot-neutral current imbalance

Thread Starter


Joined Mar 14, 2017
Hello. I'm trying to build a GFCI tester that can test both 120VAC and 240VAC outlet. It must start with a 2mA current imbalance between hot and neutral for 7 seconds. Then increase the current imbalance in steps of 1mA every 7 seconds until either 9mA has been reached or the GFCI trips. The combined weight of the tester (LCD + case +buttons + microcontroller + PCB etc.) cannot exceed 250g.

I have been thinking about creating a path involving a digital potentiometer between the H and G of the tester to shunt current from the neutral to the ground in a controllable manner. However, I have done some research and all the digipot I have read cannot handle such a large AC voltage. Is it possible to achieve the objective with a digipot, or is there other ways that should be used?