Magnum Hybrid Inverter and ground fault

In your RV's main panel, try disconnecting the 'neutral' wire (not the hot at the breaker) from the water heater to the common neutral bar. If this solves the problem you have leakage at the WH electrode (minerals in water bridging the element to ground - circular milliwatt path).

3 tons

I gave up trying to figure out the how and why of mine. (Xantrex Prosine 2.0 inverter). If shore power is plugged into a GFCI it ALWAYS trips that breaker.

UNLESS:

The breakers to the rig's GFCI circuit(s)are open (off).
THEN plug the rig into the shore power GFCI.



I discovered this out by:

Opening (OFF) all the breakers in the rig.

Connecting to the GFCI shore power.

Close main RV breaker.

Close all individual circuits one by one.

All RV breakers were on, so was the power!

I went back and unplugged and replugged with first only one breaker on, then two etc. Found that I only had a problem if breakers to either or both rig's GFCI circuits were on when shore power was connected. They worked fine if energised AFTER shore power was connected.

TIPOIO (The Innate Perversity Of Inanimate Objects.

The inverter does have a ground to neutral relay which connects ground and neutral during "inverting" mode and disconnects ground and neutral when transferring to shore power.

This neutral to ground relay is required by UL458 which is the listing for mobile inverters used in RV, Marine, Truck and any mobile application where the inverter is connected via a "cord". This relay has been in inverters since the 1980s and when installed correctly will not trip a GFCI that they are plugged into.

When installing the inverter the input neutral needs to be separated through the inverter so there is a neutral IN and a neutral OUT.

Gary

Hi Drew,

I'll attempt to plug in the Magnum by itself tomorrow without the RV being "in the loop".

You probably ought to bond the inverter case directly to the chassis ground; I suspect that's required by the NEC. I believe it is for converters, at least, and the charger part of the inverter is essentially the same thing. I doubt very much this will prevent the GFI from tripping.

It sounds like the inverter is either causing a leak to ground or bonding neutral and ground somehow. If the charger output isn't isolated from the input power properly, I could imagine it might be a sort of ground fault. Likewise, if the inverter part is bridging neutral and ground, that could very well be an actual ground fault.

(All of that is not terribly helpful, I realize; it's pretty much just reiterating your initial statement that the inverter seems to cause a ground fault.)

Do you get the trip if the output of the inverter is left disconnected—i.e. if you don't plug the shore power cord into it?

Hi Mr Wizard,

The shore power outlet is 15 amps on a house. It has a gfi. When I plug in the Magnum inverter the GFI trips on the house.

PT
you mean your shore cord, into your inverter
and GFI inside the RV trips ?

GFI is bad, or something is leaking current inside the magnum

this line does not make sense too me "The GFI is on the shore power outlet."

Hi,

The GFI is on the shore power outlet. The inverter does not have gfi outlets.

The inverter is not grounded to the frame, but the breaker box is.

I plug my shore power cord into an outlet powered by the inverter.

I imagine the negative battery terminal is bonded to the frame.

The trip occurs immediately after the transfer switch in the inverter powers up the RV. It does so even if the inverter is turned off. (i.e. in battery charging mode).

Try the inverter without its chassis ground connected to the rig's frame.

One of my inverters has a weird ground set up inside it, so when you plug shore power into it, the 120v shore power plug's ground prong has another path to the rig's frame via the inverter's chassis ground to frame wire. The result is that when I try to do a battery disconnect using the ground side of the battery the rig's 12v is still working if the shore cord is plugged into the inverter.

Yours will not be quite like that, but could have some weirdness of that type causing the rig's GFCIs to pop.

When does the trip occur?

My trailer 15a GFCI trips when my Magnum switches from inverter power to shore power, or vice versa. I think when I'm on inverter, ground and neutral are bonded at the inverter, and when on shore power, they're bonded outside the trailer, and that probably "scares" the GFCI

I also have GFI at my home power pedestal, and it does not trip when the inverter switches back to shore power, so I know there's no really ground fault occuring.