Having trouble understanding GFCI problem

[mikestock]

I have my MH in a storage lot with low capacity electrical hookup for battery charging.

Three of us are hooked into one box. After the initial bulk charge for a few seconds mine drops off to below 50 watts. The other two are pulling 95 and 325 watts respectively. I even tried running the generator while attaching the plug to avoid the charger going into bulk charge.

Any two of us are OK but the third knocks out the 20 amp GFIC. Doesn't matter which is the third, it trips.

I know we are in no way approaching 20 amps, even when first plugged in.

This station plus one other is fed by a 30 amp breaker, but it never opens.

I'm asking the owner to get the GFIC breaker checked but he said it was checked about a month ago when someone else complained. He is a hard headed individual who knows it all.

I still think something is going wrong with the GFIC breaker but I'm no expert. May go buy one myself and changing it out. Easy way out if this is the problem.

[mikestock]

Harvard wrote:
DO NOT DO THIS AT HOME

IMO, in theory, the only way you are going to get 3 RVs to work off the same GFCI is to disconnect the ground wire and allow the 3 RV chassis to float (they will float at about 60 VAC above ground). (BUT then the GFCI may detect this condition and trip accordingly)

This would be a hazard, so don't do it.....just saying. 🙂

If I understand, you're saying that 3 or 4 RV's protected by one GFCI is not feasible. That may well be the problem. I checked all of the boxes at the site and ours is the only one with a single GFCI breaker for 4 connection points. All the others have 2 HVCI's in the box.

If this is the problem I will have a daunting task, trying to explain to this headstrong owner that it needs to be changed.

[drsteve]

Camreal wrote:
Replace it with a standard plug. You have 2 more circuit breakers in line for protection and as said we got away without using them for years.

Bad idea. A circuit breaker and a GFCI protect against different hazards. A ground fault will not trip a traditional circuit breaker, and a ground fault can kill you.

[Harvard]

DO NOT DO THIS AT HOME

IMO, in theory, the only way you are going to get 3 RVs to work off the same GFCI is to disconnect the ground wire and allow the 3 RV chassis to float (they will float at about 60 VAC above ground). (BUT then the GFCI may detect this condition and trip accordingly)

This would be a hazard, so don't do it.....just saying. 🙂

[BFL13]

mikestock wrote:
All I really want to know and it's still not quite clear: Will a GFCI breaker trip, strictly due to over current and is there an obvious malfunction with the breaker, considering that any on of the three units will cause the trip?

Pianotuna's idea of stacking one RV off the other may be interesting. We don't have any outside outlets but I may try plugging my nextdoor neighbor into one of my receptacles to see what happens.

This says it protects against both overloads and ground faults:

https://www.homedepot.com/p/Square-D-Homeline-20-Amp-Single-Pole-GFCI-Circuit-Breaker-HOM120GFICP/10...

[Harvard]

road-runner wrote:

Harvard wrote:
Personally, I would suspect the GCFI to be faulty IF IT DID NOT trip with the 3 RVs. But then that is just me and my stray capacitance theories. 🙂

Just for debate's sake, if the stray capacitance were balanced, there would be equal leakage between hot-ground and neutral-ground. Exaggerated, you could leak a full amp on both sides and not trip the GFCI. As I type this, I'm agreeing with you more and more, because I've never seen the leakage to be exactly equal, with more being ground-neutral than ground-hot. So agreeing with you, I'd place my bets on the imbalance being heavier between neutral and ground.

Yes, the stray C is balanced BUT the VAC across the two is very different. The HOT wire is 120 VAC to GROUND while the NEUTRAL is almost 0.0 VAC to GROUND. Which one is going to have the most leakage current? The HOT, IMO.

[mikestock]

All I really want to know and it's still not quite clear: Will a GFCI breaker trip, strictly due to over current and is there an obvious malfunction with the breaker, considering that any on of the three units will cause the trip?

Pianotuna's idea of stacking one RV off the other may be interesting. We don't have any outside outlets but I may try plugging my nextdoor neighbor into one of my receptacles to see what happens.

[Camreal]

Replace it with a standard plug. You have 2 more circuit breakers in line for protection and as said we got away without using them for years.

[road-runner]

Harvard wrote:
Personally, I would suspect the GCFI to be faulty IF IT DID NOT trip with the 3 RVs. But then that is just me and my stray capacitance theories. 🙂

Just for debate's sake, if the stray capacitance were balanced, there would be equal leakage between hot-ground and neutral-ground. Exaggerated, you could leak a full amp on both sides and not trip the GFCI. As I type this, I'm agreeing with you more and more, because I've never seen the leakage to be exactly equal, with more being ground-neutral than ground-hot. So agreeing with you, I'd place my bets on the imbalance being heavier between neutral and ground.

[Harvard]

Personally, I would suspect the GCFI to be faulty IF IT DID NOT trip with the 3 RVs. But then that is just me and my stray capacitance theories. 🙂

[pianotuna]

My point is we need to always treat an electrical connection with respect. GFCI can and do fail. I never assume a circuit is not live. And yes, I've had a shock or two in my life.

If it is raining I plug in wearing rubber boots and silicone gloves. As well I "shuffle" (drag your feet across the ground) as I'm moving to and from the pedestal. If there is water on the ground I prop up the cord to keep it from being submerged.

I'm at a location at the moment where the GFCI prevents me from using the Magnum Inverter charger. So it is back to the OEM converter. It is a pain in the neck not having the load support feature. What is maddening is the Magnum works with some GFCI outlets, but NOT all.

[road-runner]

pianotuna wrote:

We got along just fine for a hundred years without GFCI.

If "we" means RVers, I've got no comment. If it means the general population, I remember many years ago of a friends-of-friends young couple who didn't get along well. They were both electrocuted when something electrical made its way into the small swimming pool they were in.

As to the original issue, I'm under the impression this is about a service panel GFCI breaker, which will trip for either current overload or ground fault. The possibilities have already been covered: (1) Bad breaker, (2) Excessive current, (3) Additive leakage from the 3 rigs exceeding the ground fault trip threshold. Isolation just takes time and/or money.

[mikestock]

BFL13 wrote:
Still not clear. A 30a breaker (does not pop) and a "box"/"station" that three can plug into, which is a "20a" and there is a GFCI receptacle. Or is it three "20a" GFCI receptacles in the "box" ?

Then after whatever pops, you still get some "watts", not a total cut-off? Really hard to picture the situation.

It doesn't matter which of you drops out, it can do any two of you. Does it matter which of the three ? receptacles is chosen? Can it be that the one of the three that picks the guilty receptacle( if there is one) is the unlucky one?

The main breakers are in a box about 400' away. I supplies a group of self-storage lockers besides the RV lot. There are 4 breakers serving the RV lot. Each breaker serves, I guess 3 or 4 boxes with 4-120 volt receptacles in each, protected by a GFCI breaker in each box.

[wnjj]

The OP refers to "the" 20A GFCI. I assume that means 3 RV's plugged into a multi-tap into a single receptacle, which trips when the third RV is plugged in.

[BFL13]

Still not clear. A 30a breaker (does not pop) and a "box"/"station" that three can plug into, which is a "20a" and there is a GFCI receptacle. Or is it three "20a" GFCI receptacles in the "box" ?

Then after whatever pops, you still get some "watts", not a total cut-off? Really hard to picture the situation.

It doesn't matter which of you drops out, it can do any two of you. Does it matter which of the three ? receptacles is chosen? Can it be that the one of the three that picks the guilty receptacle( if there is one) is the unlucky one?

[mikestock]

BFL13 wrote:


What is the actual set-up, to clarify the situation?

I don't know how the place is wired. It is a large lot with a dozen or so boxes. We temporarily solved to problem by one of us moving to another box using a 100 ft. cord. I didn't have enough extension to reach it.

pianotuna wrote:
50 + 90 + 325 is not going to overload a 20 amp circuit (2400 watts)

We got along just fine for a hundred years without GFCI.

I don't think that's legal, now.