Blown GFC breakers

BB_TX wrote:

DrewE wrote:

ktmrfs wrote:

2) A neutral/ground fault. If a GFCI detects ground and neutral legs are connected they trip. Code says ground and neutral can only be bonded at the panel. So for about the last 10 years or more GFCI will trip on this fault.

I believe that's been a part of the code (more specifically, the UL requirements for GFCIs) for something closer to 30 years. I've had a tough time sussing out exactly when the actual requirements came into effect, but it has been decades.

A neutral/ground fault causes a a current imbalance at the outlet due to some of the current that should go thru the neutral pin now goes thru the ground pin leading to that 5 ma or greater hot/neutral difference that causes a trip. That’s where the name ground fault circuit interrupter, GFCI, comes from.

if there is a load and ground/neutral are bonded yes, that will trip the GFCI. However even with NO loads attached it will trip on a ground/neutral short. there is signal and sense circuit to detect ground neutral bond.

And the fault does NOT repeat NOT need to go to the receptical or system ground directly. In fact a GFCI is code approved as a way to install a 3 wire outlet in 2 wire circuits. The GFCI needs to have a label saying no ground supplied. As long as neutral and hot have an imbalance it will trip. In most cases that isn't through the circuit ground but through an earth ground you or the device is standing on with a leakage path. And a GFCI is NOT guaranteed to protect you. If you get across the hot and neutral and have NO path to ground (insulated boots on insulated surface, GFCI will not trip. But you may be in for a serious shock.

Happened years ago...sold it to a Dealer...so it not an issue just a question

NO...surging Generator will not trip a GFCI Outlet

The current injection method for ground-neutral fault detection is 10+ year old technology. The National Semi/TI LM1851 worked this way. The older Fairchild/On Semi chips have some sort of circuitry that causes a sense amp to oscillate on a ground-neutral fault. TI doesn't disclose the G-N detection scheme in the data sheet for its newer GFCI chips. On Semi's NCS37010 operates with a single CT and contains a DSP. Like so many other things, GFCI operation has evolved to magic chips with very little external circuitry.

Sounds like he has an issue with the GFCI receptacle. He should replace it wi a new one.
Then report back.
Need to skip the design criteria of GFCI units, and get back to helping! Times have changed as products are upgraded with new technology.

wnjj wrote:

BB_TX wrote:

DrewE wrote:

ktmrfs wrote:

2) A neutral/ground fault. If a GFCI detects ground and neutral legs are connected they trip. Code says ground and neutral can only be bonded at the panel. So for about the last 10 years or more GFCI will trip on this fault.

I believe that's been a part of the code (more specifically, the UL requirements for GFCIs) for something closer to 30 years. I've had a tough time sussing out exactly when the actual requirements came into effect, but it has been decades.

A neutral/ground fault causes a a current imbalance at the outlet due to some of the current that should go thru the neutral pin now goes thru the ground pin leading to that 5 ma or greater hot/neutral difference that causes a trip.

They will trip even with nothing plugged into the receptacle. The GFCI device itself attempts to inject current into the neutral wire and if it flows around the neutral/ground loop it trips the hot/neutral mismatch detector you are referring to. So it really is a separate feature.

You are correct. But it is the same ground fault detection. The current injected during the test is expected to be equal thru the hot and neutral pins. But a “leak” to ground diverts some of that current leading to an imbalance.

BB_TX wrote:

DrewE wrote:

ktmrfs wrote:

2) A neutral/ground fault. If a GFCI detects ground and neutral legs are connected they trip. Code says ground and neutral can only be bonded at the panel. So for about the last 10 years or more GFCI will trip on this fault.

I believe that's been a part of the code (more specifically, the UL requirements for GFCIs) for something closer to 30 years. I've had a tough time sussing out exactly when the actual requirements came into effect, but it has been decades.

A neutral/ground fault causes a a current imbalance at the outlet due to some of the current that should go thru the neutral pin now goes thru the ground pin leading to that 5 ma or greater hot/neutral difference that causes a trip.

They will trip even with nothing plugged into the receptacle. The GFCI device itself attempts to inject current into the neutral wire and if it flows around the neutral/ground loop it trips the hot/neutral mismatch detector you are referring to. So it really is a separate feature.

DrewE wrote:

ktmrfs wrote:

2) A neutral/ground fault. If a GFCI detects ground and neutral legs are connected they trip. Code says ground and neutral can only be bonded at the panel. So for about the last 10 years or more GFCI will trip on this fault.

I believe that's been a part of the code (more specifically, the UL requirements for GFCIs) for something closer to 30 years. I've had a tough time sussing out exactly when the actual requirements came into effect, but it has been decades.

A neutral/ground fault causes a a current imbalance at the outlet due to some of the current that should go thru the neutral pin now goes thru the ground pin leading to that 5 ma or greater hot/neutral difference that causes a trip. That’s where the name ground fault circuit interrupter, GFCI, comes from.

In some cases they can also false trip due to radio frequency interference. I just replaced two GFCI breakers at my aunt’s house that kept tripping randomly every several days. After some looking online I found YouTube videos showing people keying up portable radios by their breakers that would trip them. In her case the newer version of her breakers had been redesigned to address this known problem. The originals were only about 7 years old, Eaton brand.

Some in some cases a “bad” GFCI could be one of these older ones that aren’t happy in the wrong environment and a new one fixes it.

OP: That is a GFCI receptacle not a breaker.
They go bad! Should replace with one from a hardware store not an RV store(price). Verify wiring as miss wiring causes many problems.

ktmrfs wrote:

2) A neutral/ground fault. If a GFCI detects ground and neutral legs are connected they trip. Code says ground and neutral can only be bonded at the panel. So for about the last 10 years or more GFCI will trip on this fault.

I believe that's been a part of the code (more specifically, the UL requirements for GFCIs) for something closer to 30 years. I've had a tough time sussing out exactly when the actual requirements came into effect, but it has been decades.