GFI Shore Power Outlet Kicking Out

[bgrutza]

I recently installed a 20A 125V GFI outlet on an out building at my home to keep the batteries charged on my coach.

When I go to plug in the coach the GFI outlet immediately trips.

What is the problem?

Should I not be using a GFI outlet with my coach?

[kaypsmith]

GFI outlet will only trip because of imbalance of load between the "hot" leg and the neutral leg of the load, not from overloading of the circuit, this should be handled upstream by a breaker. All that being said, many things can cause that situation. Many appliances within the coach can produce this effect because of starting load, air conditioners are notorious for this as well as other appliances. Outside plugs are generally GFI, but a 30 amp or 50 amp rv plug is not gfi.

A well grounded outlet at the location is normally used and should be safe when installed properly, usually in a sheltered situation where water can not get into the fixture.

[f313653]

Often, in fact usually, in our coach we have the same problem. I have checked everywhere and cannot find any incorrect or poor wiring or connections. Someone told me that some GFI circuits don't "Play Well" together.

At home, and at a nieces place, to use a GFI protected outlet we have to kill two breakers in the coach, plug in the shore power then turn the coach breakers back on. I discovered this when trying to trouble shoot a suspected faulty circuit in the rig:

I turned off all breakers in the coach then plugged in the shore power. Shore power GFI didn't trip.

I then turned on all other breakers one by one waiting for one to trip the GFI at the post. Nothing triped it, all circuits in the coach worked, including the GFIs in the rig. (head and galley)

I then unplugged the rig and pluged it in again: Breaker tripped.

Seveal rounds of this found 2 15A breakers that had to be off when plugging in to the GFI outlet. The breakers could then be turned on without tripping the GFI.

When I later related this to an electrician brother-in-law his first comment was GFI breakers in the coach were causing it. He said it frequently happens.

I would strongly suggest that you FIRST have all the circuits in the coach checked by an electrician. If they find no fault then the only course is to do what we do.

[kaypsmith]

Would be interesting to know how close to the coach the gfi breaker is that is tripping. The longer the run to the coach, the more apt it is that the gfi will trip. It only takes 4 to 6 milliamps difference in amperage between common and neutral to trip a gfci breaker, and the further away the load is from the breaker, the longer it will take for the neutral wire to catch up.

[f313653]

Would be interesting to know how close to the coach the gfi breaker is that is tripping. The longer the run to the coach, the more apt it is that the gfi will trip. It only takes 4 to 6 milliamps difference in amperage between common and neutral to trip a gfci breaker, and the further away the load is from the breaker, the longer it will take for the neutral wire to catch up.

With electric current travelling at pretty close to the speed of light (186,000 miles per second) and the wavelength of 60 Hz current being 5,000 miles I figure it would have to be pretty far in order to make a difference in phase.

[kaypsmith]

Actually wavelength at 60 Hz is closer to 3030 miles. Sorry to have offended you.

[Jared]

I had this same problem when I got my coach hooked-up to home power. I too install a GFI thinking that was prudent . What I was told was 2 GFI on the the same circuit is not going to work. Removed the one and all was good.