GFI Problem

DryCamper11 wrote:
Bobbo is right. A modern GFCI will trip even if there's no power on the hot lead. Many of us were taught that the GFCI compares the current going through the hot lead with the return current through the neutral and would trip if they aren't the same. Older GFCI's did that, so if there was no hot current, it wouldn't trip. Newer GFCIs are smarter and will trip if there's no load. You can try it. Stick some wire into neutral and ground on a GFCI socket and the GFCI trips. I've done it. That's what happens. If you do it, make sure you know what's neutral and what's hot !!!!!

I wondered why and got this answer:
"GFCIs contain a second toroid coil which induces a small current in the H and N wires at 120Hz. If the N and G are touching on the load side of the GFCI, there is current flow back through the main panel N-G connection; the sensing coil recognizes this as an imbalance between the H and N and trips the device. "
So, Bobbo is right. You have to disconnect the neutrals (or unplug devices, which disconnects the neutral at the plug). Turning off breakers tells you almost nothing.

Your quoted answer is correct, however, your assertion is not.

The torriod transformer needs a voltage present to test for a shorted neutral-ground wire when no load is present - no current flow.

No hot wire power, and no GFCI...

Test your theory with an uninstalled GFCI and short the ground and neutral together and tell me what happens...

Personally, I would suspect the surge guard. I would start by disconnecting the output of it and see what happens.

Thanks for all the responses. A lot of good input and thoughts. I believe that I will need to remove the neutrals and go from there. Great bunch of readers here!

Originally, I posted this:

Bobbo wrote:
These are both wrong. Turning off the breaker, by itself, will not do anything to diagnose the problem. The problem is a short between GROUND and a NEUTRAL, and the breakers do not affect that.

You MUST disconnect all of the NEUTRAL wires from the NEUTRAL buss bar to diagnose this. Only with every NEUTRAL disconnected can you know if it is between the breaker box and the Surge Guard.

Bobbo is 100% correct. His procedure will lead you to the problem. The only thing I'd add is that it may be difficult to disconnect all the neutrals, so when tracking this down, I start by unplugging devices that will unplug (the problem could be in something plugged in) and then I remove neutrals from the most likely suspects - outside sockets, water heater, etc. If that doesn't do it, I remove half the neutrals, test, then the other half.

Then I saw this post and decided more info was needed:

Sorry, but if there is NO Black 120 power, then the GFCI will not trip if the short is downstream from the breaker panel. If the CG GFCI trips with the Main RV breakers OFF, the problem is BEFORE the breaker panel in the RV. The fact he has a Surge Guard means he needs to bypass it and then see. I have 34 years as a Tech and have diagnoised (and fixed) dozens of these type issues over the years, and what I posted is the BEST way to determine where the problem is located and to start. A GFCI will NOT trip if it does NOT have Black Hot power. Just having a Neutral and a Ground (and a short/imbalance) will not cause a GFCI to trip.

Bobbo is right. A modern GFCI will trip even if there's no power on the hot lead. Many of us were taught that the GFCI compares the current going through the hot lead with the return current through the neutral and would trip if they aren't the same. Older GFCI's did that, so if there was no hot current, it wouldn't trip. Newer GFCIs are smarter and will trip if there's no load. You can try it. Stick some wire into neutral and ground on a GFCI socket and the GFCI trips. I've done it. That's what happens. If you do it, make sure you know what's neutral and what's hot !!!!!

I wondered why and got this answer:
"GFCIs contain a second toroid coil which induces a small current in the H and N wires at 120Hz. If the N and G are touching on the load side of the GFCI, there is current flow back through the main panel N-G connection; the sensing coil recognizes this as an imbalance between the H and N and trips the device. "
So, Bobbo is right. You have to disconnect the neutrals (or unplug devices, which disconnects the neutral at the plug). Turning off breakers tells you almost nothing.

dougrainer wrote:
Sorry, but if there is NO Black 120 power, then the GFCI will not trip if the short is downstream from the breaker panel. If the CG GFCI trips with the Main RV breakers OFF, the problem is BEFORE the breaker panel in the RV. The fact he has a Surge Guard means he needs to bypass it and then see. I have 34 years as a Tech and have diagnoised (and fixed) dozens of these type issues over the years, and what I posted is the BEST way to determine where the problem is located and to start. A GFCI will NOT trip if it does NOT have Black Hot power. Just having a Neutral and a Ground (and a short/imbalance) will not cause a GFCI to trip. Doug

You are correct, the ground-neutral short needs power on the hot side to generate the trip signal. That is why I stated the power cord/connectors and should have included the service wiring up to the interior service panel.

You have a neutral to ground short as stated above.

You need to disconnect all neutrals and reconnect one at a time to isolate the bad circuit. There is no shortcut to diagnosing the problem.

There is nothing normal about this happening, you have a dangerous situation and need to get it fixed.

Sorry, but if there is NO Black 120 power, then the GFCI will not trip if the short is downstream from the breaker panel. If the CG GFCI trips with the Main RV breakers OFF, the problem is BEFORE the breaker panel in the RV. The fact he has a Surge Guard means he needs to bypass it and then see. I have 34 years as a Tech and have diagnoised (and fixed) dozens of these type issues over the years, and what I posted is the BEST way to determine where the problem is located and to start. A GFCI will NOT trip if it does NOT have Black Hot power. Just having a Neutral and a Ground (and a short/imbalance) will not cause a GFCI to trip. Doug

Pretty normal. :)

If the main panel breaker in the RV is off and the GFCI still trips, it is a ground to neutral short in the RV.

If the GFCI only trips when the main circuit breaker is on, and all of the other breakers are on, then there is leakage current between the neutral and ground when one of the branch circuit breakers is energized.

Turn main on, and all of the branch circuit breakers off, and test each branch by turning only one branch breaker on at a time to see which one causes the trip.

My guess is that it is probably the power supply/converter for the batteries due to large capacitors in this device or might be the refrigerator.

Kind of a common problem...

EDIT: Saw you posted an update and the GFCI is tripping when "all" breakers are off. If this includes main, then there is a neutral to ground short somewhere in the RV before the service panel if it trips when plugged into any GFCI outlet.

The other possibility is an issue with the cable/connectors.

notruffinit wrote:
OK. So I shut off all the breakers and it will still trip the GFCI. So I guess the problem must be between my hardwired Surge Guard and the Main Breaker box (which is about 2 feet of wire)? I installed the SurgeGuard myself. I know that the common and the ground are separated. My coach is wired for 50 amp with a 50 amp Surge Guard, but I have only 1 AC unit so I almost never plug into 50 amp. I prefer to use the much smaller 30 amp cord. Anything there that I am missing?

Old-Biscuit wrote:
When you turned all the breakers off did that include the Main Breaker(s) also

Turn ALL breakers OFF and then see if GFCI still trips. If it does...problem is between pedestal and Main Panel

Bad adapter, bad cord, bad connections in cord, bad wiring.......

IF it doesn't trip then turn Main Breaker(s) ON and repeat.
Then one breaker at a time.

These are both wrong. Turning off the breaker, by itself, will not do anything to diagnose the problem. The problem is a short between GROUND and a NEUTRAL, and the breakers do not affect that.

You MUST disconnect all of the NEUTRAL wires from the NEUTRAL buss bar to diagnose this. Only with every NEUTRAL disconnected can you know if it is between the breaker box and the Surge Guard.

I will repeat my instructions for diagnosing this problem:

Bobbo wrote:
Somewhere in your RV there is a NEUTRAL to GROUND short. It could be anywhere.

Disconnect the RV from all power. Remove all NEUTRAL wires from the buss bar in the breaker box. Plug back in. If it trips, the problem is between the Surge Guard and the breaker box.

If it doesn't blow, disconnect, reattach one NEUTRAL wire, reconnect. If it blows, that is the circuit with the problem. If it doesn't blow, repeat process till it blows.

When it blows, trace that NEUTRAL to see where it connects to ground. It could be in a stripped/pinched/punctured wire, an outlet, an appliance, anywhere.

Jim Cindy wrote:
We see the same thing if we plug into any, not just campround, outlet that is GFI protected. I would be interested in an explanation too. I was previously told that it was because the RV does not have a ground to earth that the GFI is looking for.

The problem is not a lack of ground to earth. No RV has a ground to earth. The problem is a short between a NEUTRAL wire and GROUND somewhere.