Electrician Types: A Question About A Circuit Oddity

July 01, 2018, 08:23 PM

Got some outside floods on a GFCI breaker. (One light is half-way across the yard, with the bury shallow enough code requires it.)

Two switches. Three lights on one. One on the other.

Come spring the GFCI got to tripping whenever there was a good rain. Isolated the problem to one of the two older floods (by process of disconnecting circuits and waiting for rain). Replaced it.

Problem appeared solved... until it wasn't.

But now the verkakte thing was tripping without it having rained. Then I discovered it was tripping with both switches off!

Off with the panel cover. Assuming it was bad: Pulled the breaker. To be certain: Measured resistance and continuity between Hot/Neutral, Hot/Ground and Neutral/Ground.

As expected: Between Hot/Neutral: Open circuit unless a switch was on.

What was unexpected was measuring ~32k ohms (and floating around) between neutral and ground.

Light in the front is a God-knows-how-old Heath/Zenith halogen motion. All three in the back are new RAB LED motions.

I really don't want to be running around pulling those fixtures apart, especially in this heat. I'm hoping somebody's going to tell me there's something in those RAB LED fixtures that's causing this and it's normal. (E.g.: Static electricity drain?)

(I measured between neutral and ground in the Heath/Zenith motion I decommissioned, and it was open.)

July 01, 2018, 09:22 PM

Dallas239

quote:
Originally posted by ensigmatic:
Got some outside floods on a GFCI breaker. (One light is half-way across the yard, with the bury shallow enough code requires it.)

Two switches. Three lights on one. One on the other.

Come spring the GFCI got to tripping whenever there was a good rain. Isolated the problem to one of the two older floods (by process of disconnecting circuits and waiting for rain). Replaced it.

Problem appeared solved... until it wasn't.

But now the verkakte thing was tripping without it having rained. Then I discovered it was tripping with both switches off!

Off with the panel cover. Assuming it was bad: Pulled the breaker. To be certain: Measured resistance and continuity between Hot/Neutral, Hot/Ground and Neutral/Ground.

As expected: Between Hot/Neutral: Open circuit unless a switch was on.

What was unexpected was measuring ~32k ohms (and floating around) between neutral and ground.

Light in the front is a God-knows-how-old Heath/Zenith halogen motion. All three in the back are new RAB LED motions.

I really don't want to be running around pulling those fixtures apart, especially in this heat. I'm hoping somebody's going to tell me there's something in those RAB LED fixtures that's causing this and it's normal. (E.g.: Static electricity drain?)

(I measured between neutral and ground in the Heath/Zenith motion I decommissioned, and it was open.)

Are you measuring with the neutral and ground disconnected at the panel? They should be bonded at the panel, and you should have 0 volts between them. If you're measuring from the panel with the wires disconnected, then it sounds like you might have a high-impedance short circuit. Is there a photo eye in any of the fixtures?

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July 01, 2018, 10:20 PM

Some Shot

Spider webs in one of the fixtures. They don't last long between hot and ground, but they can keep between neutral and ground and drive the GFCI nuts.

July 01, 2018, 11:49 PM

ensigmatic

quote:
Originally posted by Dallas239:
Are you measuring with the neutral and ground disconnected at the panel?

Well, with neutral disconnected. I didn't bother tracking-down and disconnecting the ground wire.

It would've made little sense to check resistance between neutral and ground with them both still connected to the neutral bus

quote:
Originally posted by Dallas239:
They should be bonded at the panel, ...

That's not how a GFCI breaker works. Neutral (from the load) goes to the breaker, the breaker has a wire that goes to the neutral bus.

quote:
Originally posted by Dallas239:
... and you should have 0 volts between them.

I believe code says less than 0.7VAC.

quote:
Originally posted by Dallas239:
If you're measuring from the panel with the wires disconnected, then it sounds like you might have a high-impedance short circuit.

At 23k ohms: Yeah, pretty high-impedance.

quote:
Originally posted by Dallas239:
Is there a photo eye in any of the fixtures?

They're all motion-sensing lights, but, as I said: Their wall switches were off, so... Besides: Measurement was between neutral and ground. So it's kind of weird.

quote:
Originally posted by Some Shot:
Spider webs in one of the fixtures.

Yeah... that seems exceedingly unlikely. I installed/wired those fixtures. All four of them. There's absolutely no way there's anything like that on the wiring side, because there's absolutely no way there's any exposed neutral copper.

quote:
Originally posted by Some Shot:
... they can keep between neutral and ground and drive the GFCI nuts.

Unless neutral is faulty I'm having a hard time seeing how that could be.

Anyway... add'l info: So I thought "Hmmm... Why don't I just put that breaker back in, hook up its neutral, and see what happens?" Went back about an hour later and, sure enough: Tripped.

So the breaker is definitely defective.

I'm glad that mystery is solved, but, day-um, those GFCI breakers are expensive

July 02, 2018, 02:17 AM

Rey HRH

Might hold off until Skins show up.

You have a GFCI breaker in the breaker panel?

I don't know if the problem I had was similar to yours. I had an inside GFCI outlet in the kitchen powering two outlets in the backyard.

Same thing, GFCI kept breaking. It started during the rainy season then even when it's not raining.

I traced it to a pigtail connector. I replaced it with a newer one and wrapped it insulation so it didn't get wet. That fixed it for me.

"It did not really matter what we expected from life, but rather what life expected from us. We needed to stop asking about the meaning of life, and instead to think of ourselves as those who were being questioned by life – daily and hourly. Our answer must consist not in talk and meditation, but in right action and in right conduct. Life ultimately means taking the responsibility to find the right answer to its problems and to fulfill the tasks which it constantly sets for each individual." Viktor Frankl, Man's Search for Meaning, 1946.

July 02, 2018, 05:16 AM

Skins2881

quote:
So the breaker is definitely defective.

I'm glad that mystery is solved, but, day-um, those GFCI breakers are expensive

How did you come to this conclusion? Did problem to away with new breaker?

July 02, 2018, 05:17 AM

Blume9mm

If all you have are floods running off that circuit, why would it need to be GFI?

July 02, 2018, 08:21 AM

Skins2881

quote:
Originally posted by Blume9mm:
If all you have are floods running off that circuit, why would it need to be GFI?

Usually because if you GFI protect the lines burial depth is 12" vs 18". In rocky or clay rich soils it could save hundreds of dollars in trenching, especially if long runs.

July 02, 2018, 08:40 AM

ensigmatic

quote:
Originally posted by Skins2881:
quote:
So the breaker is definitely defective.

I'm glad that mystery is solved, but, day-um, those GFCI breakers are expensive

How did you come to this conclusion? Did problem to away with new breaker?

With the breaker installed in the panel and neither hot nor neutral connected to it, just its own neutral to the neutral bus: It tripped.

Since what it's supposed to do is detect ground fault current flow, and there could not possibly have been any current flow, I came to the conclusion it's defective

quote:
Originally posted by Blume9mm:
If all you have are floods running off that circuit, why would it need to be GFI?

Answered in the very first post and expanded-upon by Skins.

July 02, 2018, 09:35 AM

radioman

quote:
Come spring the GFCI got to tripping whenever there was a good rain.

With some of the older GFCI's, a strong radio transmitter can contribute to the problem, and make it trip more often. Not likely your issue, but I thought I'd bring it up just in case you live near some HAM station or something.

quote:
With the breaker installed in the panel and neither hot nor neutral connected to it, just its own neutral to the neutral bus: It tripped.

The rain correlation seems strange based on this.

July 02, 2018, 10:05 AM

ensigmatic

quote:
Originally posted by radioman:
The rain correlation seems strange based on this.

I think it's simply coincidence. I think the GFCI had been working properly, then, several days after I replaced the offending fixture, it failed. Perhaps related to it becoming bloody hot around these here?

That's my working hypothesis, anyway.

The way I isolated the original problem was by pruning lights from the circuit by disconnecting their hots, up in a J-box, one-by-one, until the problem stopped. I made certain it had stopped. Replaced the fixture. Had a good downpour shortly thereafter. Stayed fixed.

Then the problem came back. Only now, I eventually discovered, it'd eventually trip, rain or no rain--even when all the lights were switched off.

July 02, 2018, 01:57 PM

Aquabird

Actually a Gfci detects a differential between the common and the hot wire. If the differential is higher than I believe 9ma, then it trips.
The differential would be caused by a ground typically.

July 02, 2018, 04:25 PM

Skins2881

quote:
Originally posted by Aquabird:
Actually a Gfci detects a differential between the common and the hot wire. If the differential is higher than I believe 9ma, then it trips.
The differential would be caused by a ground typically.

It will also trip with ground fault and no load present.

#####

When trying to isolate the problem you need to disconnect both hot and neutral ensigmatic.

Hopefully it was just the breaker, you'll know for sure in a week or two.

July 02, 2018, 04:52 PM

ensigmatic

quote:
Originally posted by Skins2881:
When trying to isolate the problem you need to disconnect both hot and neutral ensigmatic.

I did. I left the GFCI breaker's neutral connection to the bus connected, but the load's hot and neutral were not.

quote:
Originally posted by Skins2881:
Hopefully it was just the breaker, you'll know for sure in a week or two.

I'm fairly confident it was.

The new breaker's in. Interestingly: An AFCI/GFCI breaker was $5 less than a GFCI-only breaker, so that's what I put in.