The idea of tripping the GFI with a small resistor is brilliant! Nice thinking. I am just throwing this out for the fun of it: My spa panel has a white coded 50A breaker, it trips at 4mA IIRC. I read somewhere on the web (from Germany I think) that this is the recommended GFI current for human protection, higher currents are more intended for property protection. It seems that a hot tub is perhaps the worst imaginable situation to have a ground fault, so it better trip at such a low current. Using a 27KΩ resistor to bleed one of the legs to ground produces 4.4mA ground current which should make the GFI trip. This produces only 0.53W of heat in the resistor, so a 0.5W resistor should be good enough as long as it trips the breaker. Even a 1/4W might be good enough given the short trip time. One would have to test this first of course. I did not think of this so my E-stop breaks all control currents to make the relays and contactors drop out.
Edit: I think white is 1mA, not 4mA. Even better.
What is the thinking on protecting the PID with a small fuse? I am not trying to be a wiseass here, just curious what your thoughts are. Let's say we’re using a PID with an SSR output. What could go wrong so that you would want the fuse to pop? My PIDs are fed from a master 5A circuit breaker, and my thinking is that I am protecting the wires should the PID have a catastrophic failure and try to smoke the 14 awg wires. I think that if a PID starts to draw excess current then it is already broken and beyond salvage. No?