GFI circuit problem

[John Fearnow]

I have had recurring problems with the GFI outlet under the sink by the shower.  The latest is that when running the genset and a load is added such as the microwave or and air conditioner and the genset speeds up, the outlet trips and I lose power to the downstream outlets and lights.  Most of the a/c lights and the TVs are downstream from this outlet.  The test button will not reset unless I take the loads off the generator and then it will reset.  The circuit breaker after the inverter is not tripped and the first GFI outlet after the circuit breaker (located in the cargo bay next to the cable tv connection) also has power.  The wiring diagram shows that the GFI outlet under the sink (the one that trips) is the next item on the circuit.  I am currently in my storage lot and do not have external power so I do not know if the same problem would happen if plugged in to shore power.  The other two circuits having breakers in the same box after the inverter are fine.  One is for the microwave and the other is for outlets in the galley area.  Could the GFI outlet be faulty even though it works when there is only a minimal load on the generator?  the one in there now is one I got from home depot recently.  Thanks for any insights.

John Fearnow
2002 Patriot -Thunder

[Randy Perry]

John, GFI outlets go bad and it seems like yours has gone south. Sounds like yours is giving you fits under load, I would replace it and I think it will solve your problem!

[marty christensen]

Randy is correct, it is probably a bad GFI.  John, also check to see if the GFI is the correct amperage.  If the inverter has a 20 amp breaker for that circuit the GFI should also be 20AMP.  Likewise if the inverter breaker is a 15amp the GFI should be a 15amp.

Marty
08 Contessa, C9

[Edward Buker]

John,

I had a GFCI outlet in the bay, that fed a lot of the coach upstairs outlets etc., that drove me nuts with tripping almost daily. It was a Pass Seymour brand and I bought another Pass Seymour GFCI and it tripped even more often. That made me suspicious that this was a marginal event on the edge of the trip circuit sensitivity. If there is a 5MA in-balance momentarily between the neutral (white) and the load (black) then the circuit trips. It is watching for stray current that is going someplace that is not accounted for and could be leaking to a path a human is involved in. (If that current could be inadvertently directed to the right person one might call this a feature)
I found a Leviton GFCI outlet at Home Depot that was made for wet environments that was priced about 30% more and it has not tripped since I replaced the Pass Seymour with this unit. I speculate that the contacts and circuits are more robust and tolerant for wet or humid environments and that helps us. I would try one of these, it is a cheap fix. If that does not fix it then some other trouble shooting would be in order. If the use of the generator was the real culprit I do not think that one GFCI on one leg would be the only thing sensing the problem. Hope this helps...

http://www.homedepot.com/buy/electrical/outlets-plugs/leviton/20-amp-weather-resistant-gfci-74942.html

Later Ed

[John Fearnow]

Thanks for the comments.  Very helpful as always. I'll try another outlet and will make sure its rated the same as the breaker.  Not sure that is the case now.  The outlet is on the same circuit that Ed mentions as being a problem in his coach but it is the first outlet inside the coach rather than the cargo bay outlet.  I also think what I have in there now is a Leviton brand.  It has a nice little green lite that is lit when it is operating properly.  It is easy to tell when it is tripped which is often unfortunately.  The GFI outlets are such a nuisance that I would almost be willing to take a shock occasionally and just leave them out.

Thanks again.
John F

[Edward Buker]

John,

If you can go into test mode on the bay one and it kills the power to the bathroom GFCI outlet that is a problem  then you can wire that bathroom one so that it is independent of protecting any other outlet down stream. This would be because the bay one is already protecting that string of outlets. (I think you will find that the bay one will not shut the bathroom circuit down but you never know for sure how they are wiring these coaches and it is worth a try.)

There is a line and load black wire terminal on the GFCI. The line terminal feeds the outlet 120V. The load terminal feeds all the follow on protected outlets. If you are already protected upstream move the load terminal black wire to the line side black wire terminal (use push terminal and screw, if two wires fit the screw terminal that is preferred) and then this outlet will just use its circuitry to protect this single outlet. If it trips under these conditions you will not be annoyed by having anything else in the coach be shut down. It would also tell you, because it is isolated from protecting any other outlets, that the circuitry in this outlet is causing the tripping. That is true if nothing is plugged into the outlet at the time. Hope this helps.

later Ed

[Joel Ashley]

GFCI electronics monitor normal current flow and sense variant micro pulses between the black and neutral wires, as Ed mentioned.  My guess is that the generator surging is being sensed and misread as a micropulse by the outlet's electronics.  There are different qualities of GFCI's available, and the cheaper ones probably aren't worth the trouble they'll eventually give you.  Our coach has it's GFCI's built into the 30 amp box's Square D circuit breakers, so replacing your faulty one with a plain outlet and sticking in a new Square D breaker/GFCI combo is an option, albeit a probably more expensive one.

I'd try taking the Home Depot Special back to them, and pick up a better quality unit as Ed suggests, or consider the breaker/GFCI option.

-Joel

[Bill Sprague]

I had a GFCI outlet in the bay, that fed a lot of the coach upstairs outlets etc., that drove me nuts

Me too.  I think I risked injury too many times from stumbling out in the dark and finding that tiny button too far inside the storage bay.  What a dumb place for Beaver to put the GFCI that runs most of the lights and outlets inside.  

So I solved it differently.

Like the rest of you, I didn't see a GFCI in anything I called home until about the 1980's.  I was well into adulthood by then and had outgrown the desire to stick strange things into electrical sockets.  

I reasoned that GFCIs might be great for stick houses with a single source of electricity.  On the other hand, the motorhome can get juice from the inverter, generator and shore power in a vast variety of locations.  Switching from one to the other seemed to much for my GFCI!  

Maybe the GFCI was an invention intended to irritate me and cause risk of falling in the dark.  Maybe I would be more likely to survive another forty years without a GFCI in that one circuit.  On removal I was not pleased with how cheaply made it appeared to be and how loose the wires seemed in their slide in connections.  I replaced it with a heavy duty outlet from a real hardware store with proper lugs on it and have not had a problem since.

For the fun of it I googled the history of the GFCI in the National Electrical Code and found this:  http://www.mikeholt.com/documents/nec/pdf/GFCI_requirement_page2.pdf

An almost related favorite story is about how my oldest son decided to teach his younger brother how to properly plug in their Atari video game.  Old son convinced young son that you had to grip the plug firmly with a finger on each plug prong.  If that house had a GFCI it would have only been in a bathroom.  Young son did it twice before old son collapsed with laughter.  

[Edward Buker]

Bill,

Very funny story about your son's experience. I also learned a healthy respect for electricity at an early age (also the hard way). If I could not solve the tripping GFCI problem I would possibly resort to your approach of elimination of the GFCI. However there is a legitimate electrical hazard with motorhomes that needs to be understood that is not so likely to happen in a house except maybe between a hot appliance and a metal sink with grounded pipes. The GFCI tries to account for all the electricity flow by having the neutral and hot lines have equal current flow (within the trip limit of 5MA). When they are dissimilar, that amounts to stray current, which may be going to ground, includes all the metal frame of the motorhome. Bay doors, main door, aluminum around the bay doors, wheels, etc, which are very available and unavoidable items that we touch. At the same time the motorhome is insulated by the tires from earth ground. Conceivably on wet ground one could get in the electrical path between earth ground and the frame being hot. Could also happen between the motorhome metal frame and a tool or appliance that becomes "hot".

I think the hazard to respect here is the metal on the motorhome becoming "hot".

 My plan if I could not solve the GFCI bay outlet was to start down the string of outlet on that circuit and use GFCIs wired independently so that the problem outlet would trip and help diagnose where the leakage was coming from. I found that the brand and version of GFCI outlet that I bought solved the problem in my case and may be worth a try in your bay. You could always just stick with the "John Wayne" approach and have your wife touch the door first if it is raining out.....

later Ed

[John Fearnow]

Update.  Ed was right.  Despite the indications on the wiring diagram, tripping the bay GFCI outlet would not cause the lavy GFCI (the problem) outlet to trip.  Tripping the CB however shuts off both the outlets. The diagram I have shows a line from the CB to the bay GFCI with three lines out: one unlabeled to an outlet; one labeled "load" to another outlet; and a third labeled "line" to the lavy GFCI.  The lavy GFCI has two lines coming out both labeled "load."  One to the vanity recpt and light switch and the second to a junction box located in the middle of the dinette overhead.  From there, through the tv relay and two more junction boxes, most of the ac lights and outlets are serviced. Thus the way I read the diagram the only path from the lavy GFCI to the CB is through the bay GFCI but either I am not reading it right or the "as built" is wired differently from the Aug 2002 diagram I have.

The Leviton GFCI I put in last week is the correct 20 amps to match the CB for this circuit.

Yeserday I checked all the connections on the GFCI before starting the generator.  When I first turned on the air conditioner, it did not trip.  After about 10 minutes it did.  And then after being reset and again starting the ac unit or the microwave, it would trip immediately.  I did notice however it would trip as soon as either one of those appliances were turned on, even before the genset surged.  The microwave and genset are of course on different circuits from the lavi GFCI.  If I turned on the TV, which is on the same circuit, the GFCI does not trip.

I guess I'll try installing another GFCI outlet, but I suspect there is some other problem. The GFCIs that I previously replaced wouldn't reset at all where this one does once the load is removed.  The electrician at home depot speculated a lose connection in the GFCI circuit somewhere.  Is that consistent with the situation here where the outlet does not trip unless the load from another circuit is added?  Instead of putting in a GFCI at each of the circuit outlets to try and locate a problem, can I use my multi-meter?  What reading would I look for...some voltage less than the other outlets?

This sure is fun!
John Fearnow
2002 patriot-thunder

[Edward Buker]

John,

This sounds like a sensitive GFCI that is tripping as soon aa little inductive kick is put back into the motorhome grid or with a little voltage drop from starting current of some appliance. If there was a real issue you would have to believe that two appliances are leakiing current or causing enough drop in one side of the line at the same time to have the GFCI in another circuit trip.

I would recommend that you do two things. Buy what I have found to be the least sensitive, most robust GFCI from a tripping viewpoint on the market and install it. Before you do that kill all the power to the coach and pull the AC panel cover. Loosen and tighten every neutral and ground wire to renew each contact point. Do the same with all the black wires going into the breakers. Be sure they are all tight. Last but not least pull each breaker enough to break the contacts and push them back in then replace the cover. There can be a voltage drop creating an in-balance due to a poor contact. This is an easy access point to get at a lot of the contact points in the wiring.

Later Ed

[Edward Buker]

John,

You are right these problems are a lot of fun.... pull your hair out kind of fun.

Regarding using a multimeter to test with. If there was an appliance plugged into a GFCI protected outlet on that circuit that was the one and only item causing the GFCI tripping, and it was consistent at tripping the GFCI each time you turned it on, then you would have a shot at measuring a constant problem source with a multimeter. The expectation there is that the leakage (missing current) is constant so it is measurable. This problem is subtle and momentary because it trips the GFCI on another circuit on start up. You would need something like a triggered oscilloscope with waveform storage capability to see what is actually going.....not everyone has one of those.

Both the units you mention pull a lot of current on start up. I suspect that momentarily these units are creating a voltage drop or a little inductive kick current surge, that creates a small in-balance between the neutral and hot line that this GFCI is seeing. You only need a small enough difference between these two lines to create a momentary 5MA of mis-matched current flow through the GFCI sense circuit to trip it. These problems can be caused by electrical interactions that are subtle and at times have nothing to do with the circuits and legs that they are installed on to protect. This is why there is a good shot that a more tolerant GFCI would fix this. Considering that the bay GFCI, that sits in parallel to this problem one on the same leg, sees the same in-balance and does not trip lets you know that this is the most sensitive GFCI in the leg. Poor connections can add resistance to the circuit in just one leg. Good connections, trying the most fault tolerant GFCIs, is about all we can do here with a reasonable effort. We will see if that solves the problem before considering the unthinkable...removing the GFCI.

If you had the means to attach any coach schematics to an Email to me I would like to have them for a reference.  e.buker@gulftel.com

later Ed

[Joel Ashley]

Good job, Ed.  Sometimes your electrical explanations are lengthy and technically over my head, but this time you held my attention throughout.  My family has a number of electricians in it, and my father was a station wireman for Pacific Power for nearly 50 years;  I'll wager one of my cousins has the oscilloscope you mentioned from their years at Tektronix.

Just wanted you to know we greatly appreciate your expertise and input on this forum.

-Reddy Kilowatt Joel  

[Edward Buker]

Thanks Joel,

It is good to help those that head out to try and fix things on their own. Sorry the explanations may get long at times. I get my fair share of help on the mechanical side of things from the forum and it is appreciated. Share what you know and we are all better off...

later Ed

[Bill Sprague]

If you had the means to attach any coach schematics to an Email to me I would like to have them for a reference....

I scanned them for my rig a few months ago to send to another member so I will send them to you.  For what it's worth, I've been collecting .pdf component service manuals as I stumble accross the last few years.  All are on line somewhere but if I'm not internet connected when I need them I have them my laptop.