GFCI

[Masscamper]

We have just brought home (new to us) a 2015 Cruiser Aire fifth wheel. Plugged it into our outside 20A outlet and it trips the GFCI. I have isolated the problem to the 15A microwave circuit. I have unplugged the microwave and used a circuit tester to verify that it wired correctly.
On this circuit there is only the circuit breaker, wire, and outlet. Should I assume the circuit breaker is the cause?

[Me_Again]

So one of the main things a GFCI does, is measure that all current going out the hot is returned on the common neutral. So somewhere in the MW circuit it is leaking current on the hot lead. As you stated that the minute you turn on that breaker, the GFCI trips even without the microwave plugged. Moisture in a slide junction box or cable comes to mind.

[Etstorm]

Also, I have found that if you plug a GFCI device into a GFCI outlet it will trip.

[Masscamper]

After a break from all the rain, the GFCI has stopped tripping at home. We have been out for a couple more weekends away and no problems there either. I'm still keeping my eyes open for the cause.

[2naEagle]

Masscamper wrote:
I checked for a junction box and / or wires under the slide. Saw no issues. Pulled the cover off the breaker box in the RV and found the wire for that circuit were tight and connected correctly. Tomorrow, I will remove the wires from the outlet and see if that fixes the issue.

Keep at it your doing all you can. Keep us posted.

[Masscamper]

I checked for a junction box and / or wires under the slide. Saw no issues. Pulled the cover off the breaker box in the RV and found the wire for that circuit were tight and connected correctly. Tomorrow, I will remove the wires from the outlet and see if that fixes the issue.

[NJRVer]

If everything is ok with the microwave unplugged then the problem is an internal one with the microwave. Trips as soon as you plug it in, or, as soon as you turn the micro on?
Not unusual. Common with blow dryers plugged into bathroom GFI. One blow dryer trips another won't.

Plug something else in the micro outlet and see what happens or if you have another microwave plug that in.

[2naEagle]

There is a good chance that the White (neutral) and Ground are touching. If the plug for microwave is easy to get to pull the plug out and look at wiring. You can try taking the plug off and separating the wires. You can also look at the trailer breaker box and make sure the White and ground are not together.

Let us know what you find.

[KD4UPL]

It is most likely in the wiring between the microwave breaker and outlet; or, at the outlet itself. It could be the black (hot) wire touching the ground. It could also (more likely) be the white (neutral) wire touching ground. Either will cause the GFCI to trip.

[RoyB]

Is it possible to plug a different MICROWAVE unit into this plug and see what it does... I had a microwave unit that for some reason really tasked the 120VAC line. It worked just fine but sometimes it trip the breaker and also made a louder sound when operating than similar microwave units would. Somehow it modulated the 120VAC line differently so to speak when being used...

We all are just plugging away with things to check - glad you taking it all in... Hard to troubleshoot things without actually being there haha...

If the tester is not showing any faults with your 120VAC receptacle where the microwave plugs into it then I would go with the circuit tester. Perhaps something is weird about the microwave unit... You are definitely doing the things I would be doing tracking down the problem...

Have you ever seen the microwave work before using a regular RV 30AMP Pedestal type connection...

I know my microwave in my 5th wheel is also an convection oven combo which I have never used that part of it... It really sounds weird when running in convection mode...

In my off-road POPUP trailer which is what I only camp in now I have used both a high wattage and low wattage manual type microwave units without any 120VAC problems... When camping off-grid I use the low wattage white faced microwave with spring loaded dial-up timer hehe... It draws around 600 watts... I only use it for heating up my coffee and doing a 5-minute baked potato wrapped in cellophane to go with my steaks on the grill...

Roy Ken

[enblethen]

Remove the receptacle and look for a small hang nail of wire making contact between the neutral and ground.

If there is any, Disconnect the power, black wire from receptacle to see if issue goes away.

[Masscamper]

This is where I am stuck in solving this issue

- microwave is unplugged
- outlet tests no problems ( wired correctly, no open grounds)
- I have isolated it to this circuit ( no faults for 48 hours with this circuit turned off at the circuit breaker)
- house outlet tests no problems
- wouldn't be the extension cord, 50/30/15 adapters as it is working with microwave circuit turned off.

Thanks for all the help so far

[RoyB]

The slide would definitely be suspect haha... all those cables move back and forth with the slide... You should be able to check the wiring for being frayed or something...

Plugging in the tester where the microwave plugs in will show an open ground perhaps... Maybe you have said that already haha...

Roy Ken

[RoyB]

My microwave has an extension 120VAC circuit receptacle located at the top of my cabinet where the microwave is plugged into it...

You could unplug the microwave here and then plug your circuit tester into this 120VAC source and see what it reads... Might have a bad connection back to the trailer 120VAC Distribution center...

All of the grounds inside the trailer all routed to the 120VAC Power Distribution center and passed through back to the 120VAC ground wire from the source. This line is also going to frame ground on the trailer. The NEUTRAL Wire for all receptacle gets routed back to a terminal strip and is isolated from from the trailer ground and passes through to the shore power Neutral connection. The Circuit breakers are only in the HOT wire loop between the shore power HOT wire connection and each of the 120VAC HOT connection at the receptacles. I guess all of this makes sense haha...

This pictorial kinda shows what i am saying here...

Google Image

Roy Ken

[Masscamper]

Yes, I have unplugged the microwave and it still trips.

If the outlet is wired correctly and the circuit breaker cannot cause the fault, that leaves the wiring. The kitchen is on a slide if that adds any clues??