Defeating GFI

[bobofthenorth]

Based on what I've read I'd say you have at least two ground fault paths.  The inverter is clearly one path since it trips the GFI immediately if you connect the bond.  Do you have an electric water heater?  If so then trip its breaker to off and see if the problem persists.

[Seangie]

Dave - If you are plugged in does the inverter need to be inverting?

On my inverter if we are plugged in the inverter switches to charging only and passes through the 120v straight to the outlet.

If your inverter is inverting while plugged into 120v then the ground and neutral will be tied together and the GFCI will blow.  

Interesting if its still blowing with the ground disconnected.  Wondering if there is an issue inside the inverter itself?  

-Sean

[David Anderson]

Dave - If you are plugged in does the inverter need to be inverting?

On my inverter if we are plugged in the inverter switches to charging only and passes through the 120v straight to the outlet.

If your inverter is inverting while plugged into 120v then the ground and neutral will be tied together and the GFCI will blow.  

Interesting if its still blowing with the ground disconnected.  Wondering if there is an issue inside the inverter itself?  

-Sean

Guess this was a question for me.  

On my SW2512 it will invert if the shore cord size selected on the menu is less than the amps being drawn by an appliance using electricity. ie, if I set cord size to 8 amps and wifey turns on a hair drier, (12 amps) the pass through feature will give me 8 amps from the power pole and 4 amps inverted off the batteries.  

It does not blow the GFI if I disconnect the case bond wire from the inverter cabinet.  I've only done this one time in 14 years since I have only hooked up to a 15 amp GFI plug once.  All other times it was either a 30 amp or 50 amp plug.  

Interesting comment about the water heater, though.  Wonder if there is something there??

David

[Oonrahnjay]

...   On my SW2512 it will invert if the shore cord size selected on the menu is less than the amps being drawn by an appliance using electricity. ie, if I set cord size to 8 amps and wifey turns on a hair drier, (12 amps) the pass through feature will give me 8 amps from the power pole and 4 amps inverted off the batteries.  ...

    You're lucky there.  On my Outback, there are many features but if the max input is set at 8 amps and wifey plugs in a hair dryer, it shuts down the input and pulls *all* the power from the inverter/batteries.  One thing I don't like ...

[Sean]

Since someone mentioned me by name, I thought I'd jump in for a minute...

First and foremost, you need to make sure there is no inadvertent ground fault in your system.  Lots of ways to do that, which have been covered here before.

That said, the Trace SW series will trip GFCI outlets all by itself, even with no ground fault.  This is due to a filter capacitor.  I wrote about the solution extensively here:
http://www.busconversions.com/bbs/index.php?topic=3285.msg29365#msg29365

Once you've ensured there is no real fault, and removed the green strap inside the case (which is NOT a ground/neutral bond and NOT a case ground) that I discussed in that post, you will STILL have a problem from the ground/neutral bonding relay that should have been installed along with the Trace.  I discussed that issue here:
http://www.busconversions.com/bbs/index.php?topic=16322.msg175595#msg175595

Lastly, even if all the above have been covered, your front-end power management and monitoring may, by itself, trip the GFI.  All I can say here is you can either live with it, or bypass the monitor.  Without seeing a schematic I can't say for sure if this is part of your problem.

Hope that helps.

-Sean

[wagwar]

First, thanks to all of you for your help.

Can you explain why I can get it to work for 4-5 minutes before the gfi blows? I have dialed the trace down to 4a charging current and it still blows.

[wagwar]

I'm beginning to believe that I have a ground - neutral bonding issue or a simple ground fault. However, I don't know how to go about running those issues down. I found the following thread wherein Sean describes a series of tests for these issues. To the best of my ability, I have done these tests and all checks out OK. Still, after about 5 - 10 minutes of charging, the GFI blows.
http://www.busconversions.com/bbs/index.php?topic=12442.msg130556#msg130556
(there is one part of Seans instructions that I did not understand "Make sure any generator or inverters aboard are also disconnected." - as I don't know specifically what that means)

I have an ESCO 350 ATS that handles the switching of generator/shore/inverter, but a conversation with ESCO TS reveals that switch does NOT do any kind of neutral/ground bonding or "lifting". I know that my generator ground and neutral are bonded to the chassis at the generator, but I am not able to discern how the neutral-ground bond is being lifted (if it in fact is). I have never had any problems with my electrical system either on gen/shore or inverter.
I welcome any suggestions as to how to proceed.

[luvrbus]

If you had a ground it would trip the GFI instantly that is the purpose taking minutes sounds like a overload but I not that up on inverters and grounds either   

[bevans6]

I have an ESCO 350 ATS that handles the switching of generator/shore/inverter, but a conversation with ESCO TS reveals that switch does NOT do any kind of neutral/ground bonding or "lifting". I know that my generator ground and neutral are bonded to the chassis at the generator, but I am not able to discern how the neutral-ground bond is being lifted (if it in fact is). I have never had any problems with my electrical system either on gen/shore or inverter.
I welcome any suggestions as to how to proceed.

The Esco ATS has relays that switch the two live leads and the one neutral lead (it's a 50 amp 120/240 volt three source ATS) so that whatever power source is providing power is switched through to the load.  Since it switches all three leads, any ground-neutral bonding that is present at the power source in use is also switched through.  That means the ground-neutral bond at the generator is "lifted" - actually just disconnected from the bus power system - when the ATS is not using the generator for power.  


Did you remove the jumper that connects that filter cap that Sean referred you to?  Is the GCFI now tripping after 3 - 5 minutes with the ground connected or disconnected to the bus?  I can't think of anything that would slowly and consistently develop a current leak in the 5 - 10 milliamp range over a period of minutes.  I just had a thought - how long is your power cord to the bus, what gauge is it, and is it coiled at all or laid out straight?  A coiled cord will inductively couple from live or neutral to ground.  Even a longish uncoiled cord can inductively couple.  

Edit:  I want to go on record that I thought of the long coiled cord thing BEFORE I googled it and found that it's a known cause of nuisance trips.  I also want to know if you've checked the obvious stuff like other outlets with stuff on them downstream of that outlet, and if it's an outside outlet possible corrosion or moisture?


Brian

[luvrbus]

Our GFI is in the breaker box inside the house not on the plug ours would always pop if she had something plugged in on one of the GFI outlets which she always did I finally tossed the 15 amp and installed a 20 amp GFI breaker in the box very seldom does it ever pop now should have went with 30 amp  

[bevans6]

What gauge is the wire fed by that breaker?

Brian

[wagwar]

Clifford, Thanks! Brian, Good to know maybe I don't have a problem with the neutral-ground bond. However, during my testing - read more below, if I throw one of my main panel breakers ON, the GFI immediately blows. If I leave all of them Off, it works for 5 - 10 minutes and then blows.

I have disconnected the green ground wire in the Trace and left it disconnected. The shore cord is a 50' 30amp 10 ga. It is not curled up - I always stretch it out and then bring it up to the bus. However, I have a 15/30 adapter at one end and a 30/50 adapter at the other. This 15 a circuit is in an outbuilding that is quite a long distance from the house panel and it has a household refrigerator on it that I cannot disconnect. In consideration of that possibility, I set my inverter to Charge only (no invert) and the charge amps to 5A. During my testing, I had all breakers in the bus Off so that only the inverter/charger was pulling a load. I have a power conditioner that indicates 117 volts AC, 5A AC and 60 hz after throwing the breaker in the bus. Those values hold steady until the gfi blows.

[wagwar]

What gauge is the wire fed by that breaker?

Hard to say, but most likely standard household 12 - 14 ga. It is enclosed in flexible metal conduit. The unknown is the gauge of the cable to the outbuilding.

[Rick 74 MC-8]

I don't know if this is possible bus could a 12 volt DC from the battery negative be bleeding off and tripping the gfi. Just thinking out loud.

[Seangie]

I don't know if this is possible bus could a 12 volt DC from the battery negative be bleeding off and tripping the gfi. Just thinking out loud.

Rick - This would be a fault only if the neutral is tied to the frame or another ground at some point....which would be a good thing to check. 

Dave (Wagwar) - Make sure that in your service panel (In the coach) your neutral bus bar is not tied to the ground bus bar at any point.  Its not uncommon in a house to see the neutral and ground tied together on the same bus but you dont want this on your Coach.  Your coach main panel needs to be treated like a sub-panel in which the ground and neutral are not tied together.  I think we all assumed this but I dont think it was specifically mentioned. 

-Sean