Tankless water heater tripping pool pump GFCI

[garisilver]

Anyone have thoughts on a reason why turning on and off a 60 amp tankless water heater (multple times while shaving) would trip a GFCI breaker for a pool pump.
Tried a new GE GFCI and it still tripped. I had a used older Bryant GFCI with me and that seems to be holding.

 

[Michael15956]

Well, I'll take a stab at this question. The two circuits are connected together physically through a bus bar and non-physically through EMF, which I suspect is what is causing the nuisance tripping.

Rapid rise and fall of a "high" (60 amps) amount of emf flux caused by opening & closing of the water heater could be interfering with the electronics in the GE pump gfci breaker, and maybe the older Bryant breaker is less sensitive.

 

[synchro]

Well, I'll take a stab at this question. The two circuits are connected together physically through a bus bar and non-physically through EMF, which I suspect is what is causing the nuisance tripping.

Rapid rise and fall of a "high" (60 amps) amount of emf flux caused by opening & closing of the water heater could be interfering with the electronics in the GE pump gfci breaker, and maybe the older Bryant breaker is less sensitive.

If magnetic fields from the rapid rise and fall of the 60A are contributing to the problem, twisting the two wires from the 2-pole breaker until they exit the panel may reduce the amount of the fields radiated. The same goes for twisting the wires on the output of the GFCI to minimize the amount that it picks up. Also, route the wires for the water heater and the pump away from eachother if possible.

Have you disconnected the load from the GFCI (at breaker or pool pump) to check whether tripping goes away?