Well pump tripping GFCI

[chl]

I think you are over thinking this. The GFCI only trips if the current leaving the Lightning on the hot wires doesn't equal the current coming back on the neutral wire. If the ground wire is connected, then it is the only other path; so if the GFCI trips there is source current coming back on the ground wire. Current can only come back on the ground wire if there some connection between it and the source (Lightning) hot wires or source neutral wire. The secondary side of an isolation xfmr is a separate circuit all together, unless it's faulty, which is unlikely.

It does require some hard thinking though.

Well in theory the isolation transformer is perfectly isolated.

But we have to consider the reality - that real transformers (even isolation transformers) have some, maybe small but not zero, capacitance between their primary and secondary, and that capacitance can pass AC. Not DC of course unless there is an electrical short.

Yes you need a complete circuit, and the ground along with the capacitance of the transformer could provide that.

Even if there is no neutral connection to the transformer primary, the neutral in the Lightning is still connected to ground. So is the center tapped secondary grounded neutral of the transformer.

Any difference is voltage between the grounded center tapped neutral of the secondary and the grounded neutral in the Lightning could cause a ground current to flow the capacitance of the transformer windings completing the circuit.

How much current would flow?
A small amount but...how much does it take to pop the GFCI?
Not much.

Just saying it is a possibility.

Without a grounded center tap (or other wire) neutral on the transformer secondary, it would be a real isolation transformer implementation and no tripping should occur. But then it would not comply with the code which requires a grounded neutral.

If you ground any secondary conductor of an isolation transformer, you eliminate the "isolation" that is canonical.

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[chl]

Not connecting the ground wire going to the Lightning and not installing a switching neutral generator panel is even cheaper which is why I indicated "A lot of people just don't connect the ground wire" in my first post on this thread. There is almost no chance that the Lightning will become energized if connected with a 50' generator extension cable.
I wouldn't remove the ground wire on the pump circuit because I don't think it will make a difference. The metal water pipes coming from the pump are grounded to the main power panel earth ground rods in most houses.

"Not connecting the ground wire..."
Cheaper in the short run, but not code compliant and dangerous.
And it could be expensive in the long run if someone is injured.

 

[chl]

I talked to the electrician today, he had an interesting thought; of course the easiest solution is unplugging the ground wire, though he proposed from the well pump and its controller. When considering the dangers he pointed out that my metal well casing is a huge ground rod.

The only danger I'm guessing is if some other part of the system is the ground path, such as an exposed wire touching a metal pipe where everything returns into the garage.

Wow, no ground wire?!

I think you'd want the ground wire that goes back to the panel so a breaker will trip if there is a fault where a hot touches the casing. That is the purpose of the ground wire. Electrical circuits 101.

If a hot wire touches a metal casing that is connected to a ground wire back to the panel, then that makes a low resistance connection for return current via the ground wire to the neutral which will overload the breaker and cause it to pop open and shut off power to the circuit.

Having the casing in the ground (grounded to earth some distance from the panel) might not provide a low enough resistance path back to the panel to cause the breaker to open.

It is similar to wiring a shed with a sub-panel. You provide ground rods but you also connect a ground wire back to the main service panel from the sub-panel.

An outbuilding sub-panel has ground rods and a ground wire back to the main service panel to ensure a safe path for fault current in case of a ground fault, protecting people from electrical shock by providing a low-resistance route for electricity to travel back to the source in the event of a problem with the wiring; essentially, it acts as a safety measure to trip the circuit breaker if a hot wire touches the metal enclosure of the sub-panel.

So a ground rod (or a metal casing in the ground) would seemingly not be enough to protect against a hot wire short to the casing - it would not trip the breaker.

See this about sub-panels:

So probably not a good idea to cut the ground - probably NEVER a good idea to eliminate the ground, a good rule of thumb.

 

[admo]

I promised I would return with the final conclusion of this thread. The electrician who has been helping me chatted the journeyman he used to work under and both said the isolation transformer would do nothing. They told me to remove the ground wire from the generator inlet box which is what the senior electrician does for his own generator (which apparently has GFI protection and that is how he solves the same issue).

So that seems to be the final solution, I slapped a label on the inlet plug so everyone knows the wire is disconnected. If someone has specific information I could give him about the isolation transformer and what it would do here specifically for a GFI issue or how it should be hooked up I could re-engage with him, but I'm not going to send him a generic blog post about "what an isolation transformer is" because he is a nice guy and that would be insulting. I do not have the technical knowledge to argue against what they both said, suggested, and are doing themselves.

Thank you everyone for the replies and help in this thread.

 

[hturnerfamily]

...and, I will also add this, for good luck: and for those who just 'can't believe' that it can be safe to remove the ground wire from the connection between the truck's ProPower output, and the device, appliance, sub panel, main panel, or, even for my camper:

look overhead at the incoming power wires from your Utility - you'll see NO GROUND WIRE.

We provide the 'Ground' at the point of service, NOT from the Utility, or, in this case, from the LIGHTNING's 'utility' output. I ground my camper... well, it already contains a ground. I ground my main house panel, at the panel, itself. etc.

 

[Maquis]

...and, I will also add this, for good luck: and for those who just 'can't believe' that it can be safe to remove the ground wire from the connection between the truck's ProPower output, and the device, appliance, sub panel, main panel, or, even for my camper:

look overhead at the incoming power wires from your Utility - you'll see NO GROUND WIRE.

We provide the 'Ground' at the point of service, NOT from the Utility, or, in this case, from the LIGHTNING's 'utility' output. I ground my camper... well, it already contains a ground. I ground my main house panel, at the panel, itself. etc.

Most people, including most electricians, do not understand grounding, its purpose, what it does and doesn’t do, or the difference between bonding and grounding.

 

[v2h8484]

...and, I will also add this, for good luck: and for those who just 'can't believe' that it can be safe to remove the ground wire from the connection between the truck's ProPower output, and the device, appliance, sub panel, main panel, or, even for my camper:

look overhead at the incoming power wires from your Utility - you'll see NO GROUND WIRE.

We provide the 'Ground' at the point of service, NOT from the Utility, or, in this case, from the LIGHTNING's 'utility' output. I ground my camper... well, it already contains a ground. I ground my main house panel, at the panel, itself. etc.

It all goes back to the "if it's not code compliant then it's not safe" mentality.

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