Shore power converter kicks off home GFI outlet

[TMG51]

I don't know much about these converters as I run everything off grid. I've used my original RV power hookup only once before, when I first got the van, and it worked then.

With weeks of cloudy weather in the northeast, I tried it again and it tripped the GFI outlet it was plugged into.

I realize campground hookups are typically 30 amp or whatnot. I was thinking that just charging my battery through the converter would not be pulling enough to overload the house circuit. Might that have been the reason the GFI tripped though?

Also, I've removed several original 120v appliances (AC, microwave) so on the off chance I accidentally left a short in the original wiring, I tried shutting off the breakers to these circuits at my converter and plugging in again, and still the GFI tripped.

Am I overloading the house circuit or do I need to chase a problem with my converter?

This is only the second time in two years I've used the hookup so I don't really need it, but I was trying to be nice to my deprived batteries. I could plug in a separate battery charger, but I'm not going to buy a separate thing to store. Looks like 3 weeks before I can leave the northeast and no sun forecast in that time.

 

[Almost There]

What else is on that circuit!

If it's not a dedicated circuit to the outlet, try turning off other things in the house first.

The other thing to try is to turn off ALL the circuits in the camper. If the GFCI doesn't snap when you plug the camper in, turn on one circuit at a time.

 

[SternWake]

This unfortunately, is fairly common, and it is not the load that the converter is presenting that is tripping it

I recall reading about it on other forums and am not sure what the resolution, if any, is.

I do know lots of GFCI's outlets last only a few years

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26331091.cfm

 

[Optimistic Paranoid]

Can you try plugging in somewhere else (also a GFI outlet) temporarily to see if it happens there?  This would tell us if the problem is on your end, or the campground's end.

 

[speedhighway46]

Did you do the 120vac wiring yourself?

I had the same problem on my Peterbilt Motorhome conversion. Long story short . . . Typical ac wiring ties the neutrals and grounds together in the service box. In a mobile application, there is no true ground. The grounds must be isolated from the neutrals; you must "float" the neutrals.

I had to rewire all of my ac circuits, starting with the service panel, to isolate the neutrals from being tied to the grounds anywhere in the system.

I would suggest Googling the National Electric Code for more more detail on floating or isolated neutrals in mobile applications.

Hope this gives you a place to start.

 

[TMG51]

It sounds like this neutral/ground conflation is the likely issue. The outlet I used two years ago was not GFI protected. I tried three outlets the other day, and all of them were GFI protected, two on different circuits, and all tripped.

In the short term I'll try plugging into a non GFI outlet. Then if needed I'll look for neutral/ground connections. I didn't wire any that way, I only removed appliances, but who knows what the conversion people did in 1999.

Thanks

 

[SternWake]

Might want to get into the original power distribution box and retighten all the screws clamping down wires anyway.

Look for discolored wire insulation, to perhaps prevent an issue in future

Does you alternator contribute to house battery?

 

[TMG51]

Does you alternator contribute to house battery?

It does, so I've been driving some every day, but I know that won't get my batteries up to 100% without driving for hours consecutively. I've just been using very little power instead... idle when I need to use my laptop... haven't turned my refrigerator on in a week now, but then with ambient temps being 40 degrees I haven't needed to.

 

[SternWake]

If your batteries are on their way out, and not just depleted, might want to think about proceeding to begin considering replacements. Usually after a bunch of time without a full charge, getting them back to full requires a lot of time at absorption voltage ( 4 to 14 hours), and following that, time at equalization voltage(16.2v), at least 1 hour perhaps 6, to get them back to their maximum remaining potential capacity where each cells specific gravity is maximized.

Without this they 'could' be approaching the edge of that cliff.

Even with it, they could be.


If you are interested, Check voltage at engine battery, and then again at house battery with engine idling, and again at 1200 rpm or so. Some fatter cabling( or another parallel circuit) from alternator to house battery could significantly increase charge current if there is more than 0.3v difference, and make your shorter drives much more effective in replenishing the house bank.

If house batteries are grounded to frame, make sure this ground is clean and tight, and a ground from frame to alternator mounting bolt will also increase charge current as well. Otherwise the current must flow from original engine to battery ground, which is undersized to begin with.

If you have interest in controlling the voltage the system seeks, let me know. I know how to trick the ECM so it does not flash the check engine light when the original VR is bypassed

 

[speedhighway46]

TKG51:

The symptoms you describe are exactly the same as the ones I had; typically non-floating neutrals somewhere in you ac system. Start your trouble shooting by separating the grounds (typically green) and the neutrals (typically white) at the service panel. 

The whites and greens should not touch anywhere within your vehicle. After separating the grounds and neutrals, if the problem continues, unplug/unwired all fixtures and appliances and then run a continuity check to see that there is no connection between the greens and whites on each branch feed circuit.

 

[sephson]

There may be nothing wrong at all. A battery charger is an inductive load, so there will be an imbalance in the current between the hot and neutral wires. GFCI's are touchy little *******s, designed to trip if they detect a fault greater that 6 mili-amps. It's possible that that the current imbalance that your charger creates may exceed this threshold.

Another possibility is that the the GFCI is not working properly. This is not even remotely unusual. I have GFCI's at work that I have to replace quite frequently because they become oversensitive to minor fault currents.

The section of the electrical code that applies specifically to RV's is Article 551 in the Special Occupancy section. I certainly wouldn't hurt to pick yourself up a copy of the NEC code book (there should be a new edition for 2017 by the way.) and spend a little time studying the thing. Just bear in mind that the Special Occupancy section does not replace the general code, it clarifies and provides exceptions for a specified application, in this case an RV.

 

[highdesertranger]

x2 on what Speed and sephson said. my vote goes to a neutral bonding issue. highdesertranger

 

[Optimistic Paranoid]

On a sorta-kinda related note, the installation and operations manual for the Morninstar 300 Pure Sine Wave inverter (Yes, inverter, not converter.  I did say sorta-kinda, right?) lists half a dozen approved GFI outlets from Cooper-Eagle and Leviton.  Anything other than those might, or might not, be problematical if used with the Morningstar.

 

[rvpopeye]

The neutral/ground separation is something you should do anyway so proceed with that , it won't cost you anything but time.
GFCIs don't like to live in moist environments. I replaced a lot of them on a regular basis on campground power posts. Try one on another site. And yes they are not all created equal but must meet some spec requirements.(When New)

 

[DannyB1954]

If the ground is not tied somewhere to the neutral, How does it carry any electricity in the event of a short? For electricity to flow it need a complete path. A ground that is not connected to something will not conduct electricity.

On boats we used an isolation transformer to create a ground that was separate from the shore power ground. This prevented any type of short on the boat from trying to go from the boat to the dock. Inside of the boat, all the grounds were tied to the main neutral just like in a house.

If the GFI is tripping it is because more electricity is flowing in one wire than the other, (what people call neutral is actually hot 50% of the time). This is called Alternating Current for a reason. 60 times every second the white and black trade polarity. The GFI sees this as power is going to ground somehow, (maybe through you), and it shuts down the outlet. It is very possible that your appliance has a partial short, (not large enough to trip a breaker, but enough to trip a GFI. Your best course of action is fix the short. If you choose not to do this, make certain the appliance is grounded and eliminate the GFI.

 

[Optimistic Paranoid]

If the ground is not tied somewhere to the neutral, How does it carry any electricity in the event of a short? For electricity to flow it need a complete path. A ground that is not connected to something will not conduct electricity.

First of all, you are absolutely right.  The so-called neutral should actually be called the RETURN wire, and it is "hot" also.  But we'll keep calling it the neutral wire here because that's what electricians call it.

In sticks and bricks, the neutral and the ground are tied together (or bonded) in the main electrical panel, where all the circuit breakers or fuses are.  Most buildings, of course, only have the one.  But sometimes you have a garage full of power tools, or a separate outbuilding like a horse barn, or whatever, and you put a separate, smaller panel in there to handle the power.  That panel gets it's power from the main panel, and is called a sub-panel.

For reasons that electrical engineers understand, but which I don't, you can only have one neutral <-> ground bond in any system, so when the electrician installs the sub-panel, he BREAKS the bonding strap that ties the neutral and the ground together in the sub-panel.  All the circuits in the sub-panel rely on the neutral <-> ground bond in the main panel.

The main electrical panel in the campground has it's neutral and ground bonded together, so RVs are actually considered sub-panels to that and the neutral and ground are NOT bonded together in their electrical panels.  They rely on the neutral <-> ground bonding via the 3rd wire in their shore cords.

In sticks and bricks, the main panel is actually grounded to the earth via that 10 foot grounding rod driven into the ground near the meter.  RVs don't have that.  In fact, they are insulated from the ground via their rubber tires.  This is called a "floating ground".  The ground wire in an RV is connected to the vehicle chassis.  If the neutral and ground were tied together in the RV, the chassis itself would be hot, and you might electrocute yourself if you touched the vehicle's metal skin while standing in a puddle outside.

BTW, in RVs with built in generators, the generator has the neutral and ground bonded together internally.  The transfer switch keeps that isolated while you are on shore power.  If you are using portable generators, some of them, especially the so called "construction generators" that contractors use, have the neutral and ground bonded together.  But some - especially the smaller Honda's and Yamaha's -DON'T.  And I don't pretend to understand the reason why.  I do know it can cause problems with GFI circuits when you are using one.

Hope that's clear.

 

[Trebor English]

- clip -

For reasons that electrical engineers understand, but which I don't, you can only have one neutral <-> ground bond in any system, so when the electrician installs the sub-panel, he BREAKS the bonding strap that ties the neutral and the ground together in the sub-panel.  All the circuits in the sub-panel rely on the neutral <-> ground bond in the main panel.

- clip -

The point is to make sure that the safety ground wire is not used to conduct neutral or return current.   If neutral current is flowing in the safety ground and the resistance goes up somewhere (corrosion, wire break) then the safety ground becomes hot.  At that point the carefully "grounded" case of your appliance is connected to a hot wire.