GFCI Problem

[croy]

Two years ago, I revamped a 20a circuit in my (USA) house. I added some outlets, and put a GFCI breaker for that circuit in the service panel.

All was well for a year and a half, then the GFCI breaker started tripping for no apparent reason. I assumed that the breaker had gone bad, so I replaced it. The new one still trips, albeit after a longer period of time (old, about three minutes; new, three to 20 hours).

I've pulled all the outlets and tightened the screws.

Still the breaker trips after some hours, whether the circuit gets loaded or not.

One thought I've had: the original romex for the longest run of this circuit is from that period of time (1960s?) when the ground wire is smaller gage than the main conductors. Could that be causing the problem?

Other ideas?

[RBM]

I don't know what it means to "revamp" a circuit. It sounds like you extended an existing circuit, but that's irrelevant. Unless required by Nec, replace the GFCI breaker with a standard breaker. If any of the outlets in the circuit require ground fault protection, install receptacles at those locations. The undersized equipment ground on older Romex won't have any affect of the function of any GFCI device.

[Stormin Mormon]

Dear JIMMIE,

I understand, a GFCI compares the hot and neutral currents.

Christopher A. Young Learn more about Jesus

.

The GFCI breaker works by detecting leakage current on the ground wire. It only needs to detect about 5ma to cause a trip.

Jimmie

[Stormin Mormon]

I've seen extension cords with cracked and leaking insullation.

Christopher A. Young Learn more about Jesus

.

Witth no obvious problems they willl still trip just because the wire is too long. This is caused by capacitive coupling between the hot wire and the ground. I dis overed this the hard way when I ran an extension courd from my back porch to my storage shed about 60 ft away. Forgot and rediscoverd it again when I ran 100ft of extension cord at an RV park.

Jimmie

[JIMMIE]

True, thats an easy way to measure leakage current on the ground wire. If there is an imbalace betewwen the two leads the difference is on the ground. But damn thats a lot to type and has been explained here about a thousand times. Kind of like you cant really meaasure resistance but you can measure the voltage drop across something if you apply a constant current or measure the current if you apply aa constant voltage but damn it all its still called an ohm meter.

Jimmie

Jimmie

[croy]

Nope.

All three outlet locations are just above the kitchen counter.

[croy]

Doesn't an outlet-style GFCI cover the whole circuit?

[RBM]

You extended an existing 20 amp circuit. Are you saying that the only things on the entire circuit are 3 kitchen counter outlets?

[croy]

This is a GF breaker (GE brand, THQL1120GFP).

Nope. I should, but I don't. Um, now that I think about it, there is a sub-panel in the garage that has three GFCI breakers in it. How would that effect this one, and what would I do about it?

Nothing plugged in at all.

Hmmm. No, I didn't think to check that, but... why would it work ok for a year and a half?

Rats! ;-) Looks like some time in the attic is in order.

Another vote for the attic.

Thanks, I'll keep that idea handy.

[croy]

Yup. There were two before, one for the fridge and stove, and one for countertop use. Now the fridge and stove are on their own brand new circuit, and the old circuit is powering three double-duplex above-counter outlets.

[croy]

Interesting, for sure.

If I count all the ups and downs and horizontals, there's about 60 to 65' in the run to the furthest outlets.

Hmmm.

[MarkK]

If there is nothing plugged into any of the outlets and now they trip and before they didn't, I would check:

1) insects or moisture in one of the boxes or cables?

2) is there a high power radio transmitter nearby, ham operator etc?

3) Does it trip at the same time that the fridge compressor or furnace or other large load kicks on/off?

Any change to one of the nearby circuits, new TV or ????

And please verify you are talking about GFI breakers and not arc fault detecting breakers or some other unusual thing..

Do come back and let us know when you find out the answer...

Mark

[HeyBub]

Yes, but when the GFCI outlet pops, you don't know immediately who is the culprit. Not that that matters much...

[HeyBub]

If you've got all the outlets on the circuit identified, try removing them from the equation one by one. After you have them ALL disconnected, and the GFCI still trips, it's off to the attic!

[RosemontCrest]

Only if it is wired properly. As RBM stated, if the GFCI outlet is installed in the first "upstream" location of the circuit and the "downstream" outlets are connected to the "load" terminals of the GFCI outlet, all outlets on that circuit will be protected.

[Stormin Mormon]

Outlet protects itself, and anything "down stream" from the outlet. Anything from the box to the GFCI outlet isn't protected.

Christopher A. Young Learn more about Jesus

.

Doesn't an outlet-style GFCI cover the whole circuit?

[Stormin Mormon]

If possible. take out the romex from the sixties, and put in new romex. The old stuff might have cracking insullation.

Christopher A. Young Learn more about Jesus

.

All the outlets on this circuit are in the kitchen (3 double-duplex).

[Stormin Mormon]

Check for reversed with:

may have a new problem with the old Romex.

And, what are the odds? Someone else is suggesting you check for bad Romex?

Christopher A. Young Learn more about Jesus

.

Hmmm. No, I didn't think to check that, but... why would it work ok for a year and a half?

Rats! ;-) Looks like some time in the attic is in order.

Another vote for the attic.

[DerbyDad03]

re: "If there is an imbalace betewwen the two leads the difference is on the ground."

Huh?

What if the difference is in the user? Current comes in on the hot, some of it leaks into the user and therefore there is less on the neutral. The GFCI will trip and no current has leaked onto the ground wire - assuming there even *is* a ground wire.

GFCI's can be used, per code, to allow the installation of 3 prong outlets on ungrounded circuits because the GFCI doesn't care about leakage to ground, it only cares if there is an imbalance between the hot and neutral.

While it is certainly possible that the leakage current could be on the ground, to state that "the GFCI breaker works by detecting leakage current on the ground wire" is just flat wrong. It works by detecting the imbalance between the hot and neutral, regardless of where it leaked to.

[JIMMIE]

If there is an imbalance that means current IS flowing in the ground circuit. Sticking yor finger in a socket and grabbing the water faucet will trip the associated GFCI because the current flowed back to ground creating a current imbalance in the hot and nuetral legs. It may or may not have went back via any particular ground wire or other path.. My mentioning wire was an assumption that had to do with the OPs problem and my earlier suggestion that the wire may be excessively long. In that case ground wire is appropriate. Just one possible solutuion out of many suggest because no one else did. It is equally correct to expalin the basic operation of a GFCI as detecting ground current as it is detecting and imbalance in current in the hot and return.

Jimmie