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GFCI troubles


Steve Hepfer
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I've been having an issue with the GFCI outlet in the bathroom which also has the residential refrigerator on the same circuit. While driving down the road the GFCI tripped thereby shutting down the fridge since it is on the inverter. I plugged the fridge into the extra outlet which is not running through the inverter and ran the generator to keep it on. I noticed that the green power indicator light was not on so I reset the outlet and it stayed on. Later, again while driving, the red indicator light on the GFCI kept flashing on and off. It seems like this is only being effected while driving and once I park the GFCI stays on. I am wondering if I actually have a bad GFCI or could this somehow be related to the inverter or the battery bank not strong enough of a charge to keep the outlet on through the inverter. I did test the battery cells with a refractometer and the readings range from 1.24 to 1.31. Any help is appreciated since I'm on the road and traveling for 8 weeks

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GFIC could be tripping when it senses ground wire to neutral or lead wire.  Might be moisture related or wires might not be insulated/tapped to prevent wires from touching while bouncing down the road.  It doesn't take much. 

I would inspect every outlet downstream from the GFCI and make sure wires are secure and tapped and the ground wire is tucked as far back into the box as possible. 

The GFIC could also be on the verge of failure.  They do go bad.  While building my house I installed at least 3 GFIC outlets that were bad.  You could try replacing GFIC as a last resort.

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Steve:

Do you have a Modified Sine Wave Inverter or a Pure Sine Wave Inverter?

I have a Magnum MSW inverter.  When I changed the GFCI in the bathroom (long story), the GFCI would trip all the time when on inverter.  I researched a bit and found that most GFCI outlets that I can purchase retail don't play well with MSW.

Xantrex did some tests and there's an application note that I can no longer find on the Xantrex website, but it's here on nanopdf.com:

https://nanopdf.com/download/gfci-compatabilities-output_pdf

Dwight

 

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3 hours ago, Dwight Lindsey said:

Steve:

Do you have a Modified Sine Wave Inverter or a Pure Sine Wave Inverter?

I have a Magnum MSW inverter.  When I changed the GFCI in the bathroom (long story), the GFCI would trip all the time when on inverter.  I researched a bit and found that most GFCI outlets that I can purchase retail don't play well with MSW.

Xantrex did some tests and there's an application note that I can no longer find on the Xantrex website, but it's here on nanopdf.com:

https://nanopdf.com/download/gfci-compatabilities-output_pdf

Dwight

 

I have a MSW inverter but have never had this problem previously. How long should they last?

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Steve:

I don't know how long they GFCIs should last.  The long story behind my replacement is that we were feeding 15 amps to a friends airstream, while running the generator, and our transfer switch failed.  The transfer switch was new, we had just replaced the original IOTA transfer switch, which had melted.

When the transfer switch failed, the system defaulted to inverter and we blew the CFCI and the inverter breakers.  We were at Bass Lake near Yosemite so we went into Oakhurst and bought a GFCI at a building supply.  I believe it was a Leviton and it really did not like the inverter.  Worked fine on shore power.

After reading the Xantrex document, I searched for the ones they passed with MSW inverters, and bought a few.  The one that worked was a Pass Seymour 2094-CC10 Safelock Self Test~~GFCI 20 AMP.  I bought it on EBAY.

I certainly don't know if the GFCI is your issue.  If the GFCI works when parked and on inverter, then you might think about looking at connections in the circuit which might be loosening a bit when bumped and shaken while driving.  I might open the outlet that the fridge is plugged into and make sure that the connections are tight.  Most of my outlets were installed using the quick connect inserts on the back of the outlets.  I'm not a fan.  If I were you I'd pull those out and wrap them around the brass and silver screws on the sides of the outlet.  I'm more confident of the connection when those screws are torqued.

Dwight

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22 hours ago, jacwjames said:

GFIC could be tripping when it senses ground wire to neutral or lead wire.  Might be moisture related or wires might not be insulated/tapped to prevent wires from touching while bouncing down the road.  It doesn't take much. 

I would inspect every outlet downstream from the GFCI and make sure wires are secure and tapped and the ground wire is tucked as far back into the box as possible. 

The GFIC could also be on the verge of failure.  They do go bad.  While building my house I installed at least 3 GFIC outlets that were bad.  You could try replacing GFIC as a last resort.

In addition to what Jim says I will add these thoughts. The way a GFIC works is there is a differential transformer between the White wire and the Black wire. There are different GFIC trip set points but the most common is 20 milliamps. As long as the difference of the current traveling out the black wire to the load versus the current traveling back on the white wire to the source is zero everything is fine. If the difference is 20 milliamps or more the GFIC will trip because some of that current must be in the safety ground (Green wire). Current in the safety ground can be caused by many things including capacitance in the winding of a motor leaking current to ground. Twenty milliamps is not a lot of current and that is why refrigerators have been known to trip GFIC circuits. You have eliminated that problem by moving the fridge to a different circuit. The output of the MSW inverter is basically a positive and negative square wave. A square wave is rich in harmonics in the rise and fall edges and the high frequencies could be leaking current to ground via the capacitance of the devices that are connected to the inverter. If you have recently added a new device to one of the outlets on the inverter you might try unplugging it as a test. Also remember that the coach grounding is changed between when the transfer switch is on shore power or the generator. Something could have changed in the generator. 

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30 minutes ago, Bob Nodine said:

In addition to what Jim says I will add these thoughts. The way a GFIC works is there is a differential transformer between the White wire and the Black wire. There are different GFIC trip set points but the most common is 20 milliamps. As long as the difference of the current traveling out the black wire to the load versus the current traveling back on the white wire to the source is zero everything is fine. If the difference is 20 milliamps or more the GFIC will trip because some of that current must be in the safety ground (Green wire). Current in the safety ground can be caused by many things including capacitance in the winding of a motor leaking current to ground. Twenty milliamps is not a lot of current and that is why refrigerators have been known to trip GFIC circuits. You have eliminated that problem by moving the fridge to a different circuit. The output of the MSW inverter is basically a positive and negative square wave. A square wave is rich in harmonics in the rise and fall edges and the high frequencies could be leaking current to ground via the capacitance of the devices that are connected to the inverter. If you have recently added a new device to one of the outlets on the inverter you might try unplugging it as a test. Also remember that the coach grounding is changed between when the transfer switch is on shore power or the generator. Something could have changed in the generator. 

Bob, could the problem also be the house batteries? I have noticed that the panel stays on Float Charging at 13.4 volts. I can't recall the last time it said Full Charge - perhaps a few days ago in Florida. 

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22 hours ago, Steve Hepfer said:

Bob, could the problem also be the house batteries? I have noticed that the panel stays on Float Charging at 13.4 volts. I can't recall the last time it said Full Charge - perhaps a few days ago in Florida. 

I would not suspect the house batteries would be causing a problem with the GFIC. Float Charging is the normal charge mode for fully charged batteries. Once your batteries are charged the inverter/charger goes to Float mode to keep the batteries from boiling over or draining down from parasitic loads. If you disconnect from shore power and have the generator off and then run the microwave on the inverter with a cup of water for about 30 seconds and then either start the generator or connect back to shore power you should see the charger come out of Float mode.

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Good morning - I had a similar problem several years ago (GFCI would not stay energized - same symptoms) - at the time, I had a modified sign wave inverter (have since changed to pure sign wave) in my 2006 Dip - I called Magnum tech support & they recommended a certain model number (Leviton GFCI - sorry, don't recall model #, nor the phone #)  might be worth a call to them - hope this might help!

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You indicate that this has not been a problem before and only happens now while driving.  This to me indicates it is a "shorting" problem where wires are either touching each other or ground.  Could be a place on the wire that has had it's insulation rubbed off compromised. 

My recommendation would be to disconnect the load side of the GFIC wires and see if it doesn't trip while driving.  If it stays on then the problem is down stream.  You will have to determine the route of the daisy chained outlets and isolate one at a time.  You might guess and disconnect one of the center outlets, reconnect the wires at the GFIC and see if stays in, if it does the problem is further down stream.  Not knowing the routing of the daisy chain will be the challenging part. 

I had to track down problem circuits in the new house I wired.  Even knowing how the circuits were wired it still was a challenge.  In two cases I actually had bad feeds from the main panel and concluded that the dry wallers or finish guy hit the homerun wire with a screw.  I found latter that the finisher was using longer screws to pull wall board in, drywallers used the standard 1 5/8" screws.   I had 2 home runs running the same general vicinity that both were shorted.  (do you know how hard it is to replace wires from the service panel to the individual rooms when the drywall is up and finished). 

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On 9/10/2020 at 7:00 AM, Steve Hepfer said:

I've been having an issue with the GFCI outlet in the bathroom which also has the residential refrigerator on the same circuit. While driving down the road the GFCI tripped thereby shutting down the fridge since it is on the inverter. I plugged the fridge into the extra outlet which is not running through the inverter and ran the generator to keep it on. I noticed that the green power indicator light was not on so I reset the outlet and it stayed on. Later, again while driving, the red indicator light on the GFCI kept flashing on and off. It seems like this is only being effected while driving and once I park the GFCI stays on. I am wondering if I actually have a bad GFCI or could this somehow be related to the inverter or the battery bank not strong enough of a charge to keep the outlet on through the inverter. I did test the battery cells with a refractometer and the readings range from 1.24 to 1.31. Any help is appreciated since I'm on the road and traveling for 8 weeks

I have the exact same problem! Haven't figured it out yet. 

Tom Staska  06 Dip

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I have the exact same problem with my 06 Dip. Haven't figured it out yet. I've replaced the GFCI, no luck. I've had a Samsung residential frig for about 6 years but I've only had the problem for the last 6 months. I always have my inverter on even when I'm on shore power. It only happens when I'm not on shore power. It usually happens shortly after we start moving, then I reset it and it's ok till I pull into a rest stop  or fuel stop and shut the engine off. 

Tom Staska  06 Dip

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8 hours ago, jacwjames said:

You indicate that this has not been a problem before and only happens now while driving.  This to me indicates it is a "shorting" problem where wires are either touching each other or ground.  Could be a place on the wire that has had it's insulation rubbed off compromised. 

My recommendation would be to disconnect the load side of the GFIC wires and see if it doesn't trip while driving.  If it stays on then the problem is down stream.  You will have to determine the route of the daisy chained outlets and isolate one at a time.  You might guess and disconnect one of the center outlets, reconnect the wires at the GFIC and see if stays in, if it does the problem is further down stream.  Not knowing the routing of the daisy chain will be the challenging part. 

I had to track down problem circuits in the new house I wired.  Even knowing how the circuits were wired it still was a challenge.  In two cases I actually had bad feeds from the main panel and concluded that the dry wallers or finish guy hit the homerun wire with a screw.  I found latter that the finisher was using longer screws to pull wall board in, drywallers used the standard 1 5/8" screws.   I had 2 home runs running the same general vicinity that both were shorted.  (do you know how hard it is to replace wires from the service panel to the individual rooms when the drywall is up and finished). 

So far the problem has not recurred. The first instance it tripped but was able to be reset. Later the indicator light was flashing red. I pushed the test button and then reset it.  It hasn't tripped since.

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