Defeating GFI

[wagwar]

Hi,

We're sitting at friends' place and they have a 15a outlet nearby. It is protected by a GFCI so when I try to plug in the bus (using 30/15/50 adapters) it blows the gfci. I seem to recall a discussion about this on the forum, but I can't seem to find it. Does anyone know how I can defeat the GFI temporarily so I can plug in? My power runs through an automatic conditioner that tests voltage, polarity, etc. before allowing the power into the automatic switch which then goes into the main panel. I also have a Trace sw4024 in the mix.

Thanks!

[Kitt]

Most likely you have the neutral and ground tied together somewhere on your bus. That's what will trip the GFCI.

The only times that neutral and ground should be tied together on your bus is when it is generating its own electricity and you aren't tied to shore power. In other words, only when you are running on inverter or generator.

So your generator can have its neutral and ground tied together all of the time as long as your transfer switch switches neutral as well as the hot(s), which it should.

The inverter should only tie neutral and ground together when it is running on battery (inverting). Some inverters have a relay inside to tie them together as needed, some don't and are tied together all of the time. I don't recall if that Trace does or not.

As far as bypassing the GFCI, you would need to require the outlet and your friend's house. But that would be defeating an important safety feature.

Hope that helps.

-Kitt

[eagle19952]

it does not take very many amps to trip...how many things are drawing current in your coach...
i would not defeat the gfci...it's doing it's job.

believe it or not i carry one of these....and enough 4wire SO Cable to use it....and an assortment of 50 amp breakers....

[bevans6]

The only way to un-GFCI a GFCI outlet is to take it out and replace it with a non-GFCI outlet.  If you want to do that on a temporary basis you could, but you would lose the GFCI protection on not only that outlet but also on any down-stream outlets.  Is that good or bad?  90% of outlets in my house are non-GFCI including the outside outlets, since they were installed before the advent of GFCI.  GFCI detects the current difference between live and neutral, it does not need a ground to work.  If your bus is tripping it, I would start by opening the main breaker in the bus and see if it still trips, then close it and open all of the other breakers, etc.  If you have neutral bonded to ground somewhere in the bus, you'll need to find it.  With a neutral-ground bond, some of the return current will pass through the ground, and as little as 5 milliamps can cause a GFCI to trip.  That's not a lot of leakage to ground.

[Rick 74 MC-8]

It could be tripping the GFI before the automatic transfer in the inverter is switching if you got two of those ground adapters like the old days when outlets were not grounded and tried connecting the ground after it gets power. just be careful because you might really have a problem

[Seangie]

Hi,

We're sitting at friends' place and they have a 15a outlet nearby. It is protected by a GFCI so when I try to plug in the bus (using 30/15/50 adapters) it blows the gfci. I seem to recall a discussion about this on the forum, but I can't seem to find it. Does anyone know how I can defeat the GFI temporarily so I can plug in? My power runs through an automatic conditioner that tests voltage, polarity, etc. before allowing the power into the automatic switch which then goes into the main panel. I also have a Trace sw4024 in the mix.

Thanks!

Dave - are you using a cheater adapter that ties (2) 20 amp or (1) 30amp and (1) 20 amp to a 50amp plug?  Those tie the ground and neutral together in the plug itself to work.  I've got one I use all the time and it will not work on any gfci outlet.  There is no way to beat it except to change out the outlet or find another non-gfci outlet.  Also - if there is a gfci outlet anywhere in the circuit it will trip the breaker even if you have it plugged into a non-gfci plug.

There are 30 amp to 50amp adapters that do not tie both hot legs together that will work fine (unless as previously mentioned the neutral and ground are bonded somewhere in the bus but they should not be bonded in the bus...only at the generator when that is running and possibly the inverter when on battery only power)but you will only get power to one leg of the breaker box.  We have our electrical so the charger/inverter, hot water heater and front AC are all on one leg of the electrical and everything else on the other so that we can use just one 20amp connection and breaker on/off as needed to get by.

-Sean

[bobofthenorth]

As others have pointed out, you may have a legitimate ground fault that you should find and fix.  Common culprits are just plain bad wiring or possibly an electric water heater where the element is starting to deteriorate, allowing current to leak to ground through the water.  With your inverter turned off use a VOM to check for continuity between the green and white conductors on your shore cord.  If they are isolated then the inverter is likely the problem.  In my case my old Heart inverters won't release the bond fast enough to allow us to use a GFCI outlet.  We've had some bad days as a result and we have developed workarounds for those situations.  I'm not going to tell you in an open forum how to get around NEC, Google is your friend.

[David Anderson]

I have a Trace SW2512 (vintage 1999 year model).  It acts as a pass through in addition to a battery charger when tied to the grid or running on the genny.  I suspect yours does the same.  The neutral and ground are tied together at the inverter case with a green wire and a nut with a lock washer which is easily accessible on mine.   I had your problem and temporarily disconnected the case ground at the inverter to use the GFI plug at the pole.  Doing this creates only one bond at the grid pole. 

We've had numerous discussion here about grounds and neutrals.  No one knows why the ground on the inverter is not released when external power is applied.  It should be to avoid double bonding.  It should have been designed to bond to the neutral only when stand alone inverting.  If on the grid the bond should be at the pole.  If on genny the bond should be at the genny. 

Sean is our electric guru.  He should jump in with some better advice.

Good luck

David

[Seangie]

Sean is our electric guru.  He should jump in with some better advice.

Good luck

David

Just to Clarify....I am not the Sean you are looking for.....

-Sean (not the original)

[Jriddle]

I have a Trace SW2512 (vintage 1999 year model).  It acts as a pass through in addition to a battery charger when tied to the grid or running on the genny.  I suspect yours does the same.  The neutral and ground are tied together at the inverter case with a green wire and a nut with a lock washer which is easily accessible on mine.   I had your problem and temporarily disconnected the case ground at the inverter to use the GFI plug at the pole.  Doing this creates only one bond at the grid pole.  

We've had numerous discussion here about grounds and neutrals.  No one knows why the ground on the inverter is not released when external power is applied.  It should be to avoid double bonding.  It should have been designed to bond to the neutral only when stand alone inverting.  If on the grid the bond should be at the pole.  If on genny the bond should be at the genny.  

Sean is our electric guru.  He should jump in with some better advice.

Good luck

David

I also had this problem. I built Sean's transfer switch and have A SW4024. I had to be sure the hot and neutral blades made contact first by tilting the plug. Once the switch had shore power it would then switch the neutral and then it wouldn't trip the GCFI. It only takes a split second then ground blade can engage. I don't really know how to explain this any better. You could look for an adaptor that has a slightly shorter ground prong. (Hint) Then the hot and neutral prongs would engage first before the ground prong.

John

[Boomer]

I also have a SW4024 (RV) and have the same issue.  I disconnected the green wire on the inverter and it still tripped the GFIC even with the inverter input dialed down to 12A.  Don't think there is a way around it.  Heard you could tilt the plug when connecting but have not personally tried it.  I had to replace a GFIC plug in my shop with a regular one to solve the problem.  On the road it's a different story.

[Oonrahnjay]

I also had this problem. I built Sean's transfer switch and have A SW4024. I had to be sure the hot and neutral blades made contact first by tilting the plug. Once the switch had shore power it would then switch the neutral and then it wouldn't trip the GCFI. It only takes a split second then ground blade can engage. I don't really know how to explain this any better. You could look for an adaptor that has a slightly shorter ground prong. (Hint) Then the hot and neutral prongs would engage first before the ground prong.  John

     Yes, this is a question that's bothered me.  The standard safety feature is that the ground should be connected in a standard 15-amp plug before the hot and neutral prongs make connection.  That's a good thing.  But with my bus, it gets me into the loop of the ground section of the transfer switch tripping the GCFI socket.  Most transfer switches are made to properly bond/unbond ground as they switch from the different power inputs and in some of the conditions, the transfer switch makes its internal ground connection before it switches the hot and neutral connections.  This is a good safety feature.  Unfortunately, it "fools" at GCFI into thinking that there is a ground fault.

     In a previous post, someone gave details of a "delay box" for just such issues.  You take an ordinary insulated electrical connector box and install a section of Romex (or your preferred 120V cable) with the hot and neutral straight-through.  For the ground cable, put in a normally-closed push switch; then install a male and female plug/socket on each end of the cable.  If your system is working safely, you should be able to hold down the push switch, plug into the GCFI and when the transfer switch has completed its switch over to shore-power, release the push switch.  Someone also said that you can get the same result by cutting down the ground pin on the extension cord plug and plugging in the cord slowly into the GCFI.  (On my bus, you can hear the transfer switch make a dull "clunck" sound as it switches and sometimes this is 1-2 seconds after I connect the shore cord.)

     What worries me is that it seems very hard to tell the difference between "Safe - Normal but has to be overridden for a second or two" and "Unsafe - not Normal and if you override it, you're creating an unsafe condition". 

     Everything about the operation of my bus leads me to think that the grounds and neutrals are correctly bonded and unbonded by the automatic switching of the transfer switch and inverter.  But I have this issue with GCFI outlets.  Where I often park, there is an outlet box that has both an ordinary three-connector outlet and a GCFI outlet.  If I plug into the ordinary outlet, my system works fine and all the testers indicate that I have no problem.  I have not tried any "dodge" on a GCFI -- maybe the override box or the shortened ground pin would be fine -- and maybe it would all work OK.  I don't know but I am just not comfortable with a situation that doesn't make common and dangerous faults plain.

[wagwar]

Still no joy.
Here's what I've tried:
1. Turn all the breakers in the main panel off.
2. Turn the AC input breaker to the inverter off.
3. Disconnect the 'green' ground inside the inverter.
4. Turn the inverter off.
5. plug into the gfi and turn the main breaker (pedestal to bus) on.

At this point, the power conditioner cuts in allowing AC voltage into the bus. The ATS cuts in allowing power to the panels and (I assume) bonds the ground-neutral. All is well. The inverter indicates an AC input voltage OK.

6. Reconnect the green ground inside the inverter. The gfi blows.

I have tried the above in different orders, but same result.

It seems to me that if I had a ground fault in the bus or a problem w/ the ground-neutral bonding, turning all the breakers in the main panel would eliminate that as a possible cause. What am I missing?

Is it acceptable to leave the green wire disconnected inside the inverter - just long enough to get my batteries charged back up?

Thanks,
Jim

[bevans6]

I think the inverter is bonding neutral and ground.  Since you are plugged into a GFCI outlet you will be protected if anything in the bus develops a path to ground, so I would go ahead and charge your batteries with ground disconnected.  If anything can/will give you a shock for any reason, the gfci will trip because there will be an imbalance in the current in live and neutral (whatever current is leaking out and shocking you, etc).   This is a permitted application to use GFCI to protect ungrounded outlets, and what you're doing amounts to the same thing.

Brian

[wagwar]

I tried leaving the green ground to the inverter disconnected. It worked ok for a fe minutes, the the gfi kicked out again. I set the charge amps on the inverter to 4 and it still kicks out after about 5 minutes. Any other suggestions?