Enclosed Trailer 110V Trips GFCI When Plugged In

[39CAMC]

Summary/TL;DR: Its obviously a floating or bonded ground issues, my question is How do I fix it?

We have an enclosed trailer we use to sell my companies products out of. I has 110V wiring in it with an reverse plug on the front of the trailer.

At the shop, we power it from a regular extension cord. At events, we use either a Honda EU2000 inverter generator or a Champion 10029 3400W Inverter generator.

It has worked fine for several years.

We upgraded a piece of equipment and need 220V so I picked up a Briggs Q6500 inverter generator which works great for the 220V equipment but when I hook the 110v outlet to the trailer, the GFCI outlet on the generator trips immediately.

This generator has a Bonded Ground(I think?) (below from the manual)

>>>>>>>>>>>>>>>>>>>>
System Ground
The generator has a system ground that connects the generator
frame components to the ground terminals on the AC output
receptacles. The system ground is connected to the AC neutral
wire (the neutral is bonded to the generator frame).
>>>>>>>>>>>>>>>>>>>>>

I am not sure on the ground type on the other generators, but they also do not have GFCI outlets.

So, as noted above, it is presumably an issue with a bonded versus floating ground.

But I guess I do not know where to start to fix the problem.

Do I need to change the wiring in the trailer? It has an RV type breaker box in it. Or will one of those plugs like this work?

https://inverterservicecenter.com/s...qU6A-SRa8M04GJov7mbi70hThSqccKlIaAgFlEALw_wcB

Thanks in advance for any help,

DaveW

 

[nadogail]

IMHO, The GFCI Is looking for an imbalance between the current going into the load and the current returning from the load.

Any imbalance that exceeds the very narrow limits of the GFCI will cause a trip action.

 

[mark-NJ]

^^^

This, exactly.

GFCIs don't actually have anything whatsoever to do with ground. As stated above, whatever current goes "out" [hot] needs to "return" [neutral]. There's a dinky little current transformer inside the GFCI though which the H & N both flow. Kirchoff's law states that "all current into & out of a node equals zero", and it's that law by which these devices work. Let's say 1 A flows out, but only 900mA returns. The differential of 100mA went "somewhere else", and because the "out & back" are unequal, the GFCI trips.

You either have 1.) a bad GFCI, 2.) some current returning on a neutral that the GFCI is unaware of [usually a wiring mistake] or 3.) a legit ground fault.

Note that the amount of current is unimportant. It's the lack of balance between H & N that causes the tripping. If the imbalance exceeds 4-6mA, the GFCI will trip.

 

[wyliesdiesels]

Summary/TL;DR: Its obviously a floating or bonded ground issue, my question is How do I fix it?

nope.

A GFCI does not care about whats going on with the ground wire. A GFCI actually doesnt even connect to or monitor whats flowing on a ground wire.

Instead, the GFCI monitors the current on the hot wire and neutral. If there is an imbalance of more than 5ma, then it will trip.

Also, if you have a neutral bonded to ground somewhere downstream of a GFCI, it will cause the GFCI to trip....

We have an enclosed trailer we use to sell my companies products out of. I has 110V wiring in it with an reverse plug on the front of the trailer.

At the shop, we power it from a regular extension cord. At events, we use either a Honda EU2000 inverter generator or a Champion 10029 3400W Inverter generator.

It has worked fine for several years.

We upgraded a piece of equipment and need 220V so I picked up a Briggs Q6500 inverter generator which works great for the 220V equipment but when I hook the 110v outlet to the trailer, the GFCI outlet on the generator trips immediately.

This generator has a Bonded Ground(I think?) (below from the manual)

>>>>>>>>>>>>>>>>>>>>
System Ground
The generator has a system ground that connects the generator
frame components to the ground terminals on the AC output
receptacles. The system ground is connected to the AC neutral
wire (the neutral is bonded to the generator frame).
>>>>>>>>>>>>>>>>>>>>>

NO thats not the right thing to be looking at. the ground should be bonded to all metallic pathways. Together with the bonded neutral, it assures that things which shouldnt be energized, cause the breaker to trip, when they do become energized.

Notice the manual says bonded neutral?

I am not sure on the ground type on the other generators, but they also do not have GFCI outlets.

So, as noted above, it is presumably an issue with a bonded versus floating ground.

But I guess I do not know where to start to fix the problem.

Do I need to change the wiring in the trailer? It has an RV type breaker box in it. Or will one of those plugs like this work?

https://inverterservicecenter.com/s...qU6A-SRa8M04GJov7mbi70hThSqccKlIaAgFlEALw_wcB

Thanks in advance for any help,

DaveW

What you should be looking at is the bonded neutral as shown in red above in your quote of the manual, but not on the generator. The generator SHOULD have a bonded neutral since it is the power source. you need to look at the trailer and figure out where the neutral is bonded. this is causing the GFCI to trip.

 

[Metal-Marc]

I haven't heard about Kirchoff in over a quarter of a century.

 

[TractorJeff]

Could he run a Ground Wire from the Trailer to the Generator Frame to Bond the Source to the Load? This would put them at the same Potential?

 

[39CAMC]

nope.

A GFCI does not care about whats going on with the ground wire. A GFCI actually doesnt even connect to or monitor whats flowing on a ground wire.

Instead, the GFCI monitors the current on the hot wire and neutral. If there is an imbalance of more than 5ma, then it will trip.

Also, if you have a neutral bonded to ground somewhere downstream of a GFCI, it will cause the GFCI to trip....



NO thats not the right thing to be looking at. the ground should be bonded to all metallic pathways. Together with the bonded neutral, it assures that things which shouldnt be energized, cause the breaker to trip, when they do become energized.

Notice the manual says bonded neutral?



What you should be looking at is the bonded neutral as shown in red above in your quote of the manual, but not on the generator. The generator SHOULD have a bonded neutral since it is the power source. you need to look at the trailer and figure out where the neutral is bonded. this is causing the GFCI to trip.

Ah, ok. It makes more sense now. I will check the wiring on the trailer (when it warms up) and see what is going on.

Thanks so much everyone for helping me understand!

DaveW

 

[TRWham]

Could he run a Ground Wire from the Trailer to the Generator Frame to Bond the Source to the Load? This would put them at the same Potential?

The current returning from the load will split among all possible paths to get back to the source (or at least to a lower potential). Assuming the ground and neutral are bonded within the trailer, some of the return current is sneaking back to the generator via the ground conductor in the cord. The GFCI detects that some current is missing and trips. Additional paths that are also bonded to the trailer neutral would only split even more of the return current away from the neutral conductor.

 

[wyliesdiesels]

Could he run a Ground Wire from the Trailer to the Generator Frame to Bond the Source to the Load? This would put them at the same Potential?

Nope. That wont do anything but continue the nuissance trips.

Go back to the basic theory behind the functions of a GFCI.

If there is an alternate pathway, besides neutral, for that current to return to the generator, then the GFCI will trip because it wont see the current returning on the neutral.

 

[TractorJeff]

Thanks TRWham and wyliesdiesels!
The part about the "missing" Current on the Neutral I didn't think about!
Makes perfect sense!
Thanks!

 

[mark-NJ]

Kirchoff wins again!

 

[Metal-Marc]

Kirchoff wins again!

It's the law.