Transfer switch with switching neutral: the key to using these things in UPS mode?

[PunkerTFC]

I have a Pecron E1500LFP I'd like to run in UPS mode to automatically power my pellet stove when the grid goes down. From everything I've read, using a transfer switch that only breaks the hot (i.e. all the normal Reliance products) will create a neutral-ground loop if you connect the solar generator output and input at the same time.

It seems like using a transfer switch that can also switch the neutral (i.e. EZ Generator Switch or something similar) wouldn't have that problem. Everything will still have a common ground, but the power station output hot AND neutral will be isolated from the input hot AND neutral. Basically the exact same way it works if I just plug the pellet stove directly into the power station. Am I missing something here? Just want to do a sanity check before I wire everything up and blow up my Pecron.

 

[ricardocello]

Thinking Out Loud
If everything has a common ground,
and the grid neutral is bonded to the common ground at the main panel,
and you put the transfer switch on the input to the Pecron to isolate hot and neutral (but not ground) when in ups mode,
and you have a ground fault at the pellet stove,
there will be no return path for that current to the Pecron.
Unless it internally bonds ground and neutral (which probably defeats the whole purpose anyway).

You could put a GFCI extension cord on the Pecron output to check for current imbalance and for safety.
Doesn’t look like it has one internally.
ask @timselectric

 

[ricardocello]

deleted duplicate message

 

[PunkerTFC]

Thinking Out Loud
If everything has a common ground,
and the grid neutral is bonded to the common ground at the main panel,
and you put the transfer switch on the input to the Pecron to isolate hot and neutral (but not ground) when in ups mode,
and you have a ground fault at the pellet stove,
there will be no return path for that current to the Pecron.
Unless it internally bonds ground and neutral (which probably defeats the whole purpose anyway).

You could put a GFCI extension cord on the Pecron output to check for current imbalance and for safety.
Doesn’t look like it has one internally.
ask @timselectric

I don't think you're wrong, but this is also the same as when the pellet stove is plugged straight into the pecron (which is the situation I'm in now). There is definitely not an internal N-G bond when the pecron is running isolated from the house; I'm measuring ~47 vac from output neutral to ground. Interestingly when I'm plugged in to the house but the breaker for the circuit I'm plugged into is off, I only see 12 vac from neutral to ground.

 

[PunkerTFC]

Well, I wired it up and it works as intended! The pecron is connected to both the transfer switch that powers the room with my pellet stove, and the AC input being powered by a separate circuit. It's running in UPS mode just fine and when I kill the power to the main panel it's powering the whole room with the inverter. When I power up the panel it goes back to UPS and recharges the battery. Just what I wanted!