I have a dual pole screw-in Cuttler Hammer breaker with ground fault interrupter, the connected poles have 50 amps each. The breaker is used to connect to a hot tub. I'd like to know if the breaker is okay.

I've tested and found current on the IN side, with none on OUT, with the switch firmly on. The GFI doesn't work, that is, when pressed it doesn't return. I've unplugged the easy stuff in the hot tub (i.e. pumps, lights). The heater is hard wired. I had trouble with the GFI on the breaker before and stopped testing it for fear that I wouldn't be able to reset it. I had to remove the pump, so I shut off the breaker. Now the breaker doesn't work at all.

Thanks for your help.

Cut the main power in the panel. Remove the two outgoing wires on the breaker. Restore power. See if the breaker will stay in the on position with nothing connected. If it stays on you have a real ground fault.

You cannot hold a breaker "ON" because of the way it's designed.

You stopped testing the breaker because you feared you could not reset it?

I am glad I was not visiting and sitting in your tub with malfunctioning GFI breaker.

Time for a new breaker, and per the manufacturers instructions , all GFI devices must be tested monthly.