Hey Electricians: GFCI Question/Problem
 

Is a GFCI breaker on an electrical panel more sensitive than a GFCI outlet?

Problem:
A GFCI breaker in an electrical panel has started tripping. It runs to an outlet in the yard which has powered a pump in a water feature for 10 years or so.

When I plug one of the other, smaller pumps into the same outlet, the breaker doesn't trip.

So -- it seems obvious that it's the pump.

But -- when I run an extension cord to the same pump and plug it into either a regular outlet or a GFCI outlet -- it runs fine. Nothing trips. So, although the pump has started tripping the panel GFCI, it doesn't trip a regular outlet or an outlet with a GFCI.

I thought (hoped) maybe the breaker had an issue. Replaced it. Stayed the same.

So, it's probably the pump or its electrical cord. But the issue has to be minuscule if it won't trip a GFCI outlet.

Suggestions/Ideas?

(My next step is to replace the pump. But it's large, expensive, will be a significant chore to replace and I don't want to get into it if there's something else I should be testing/checking/etc. first.)

Thanks.

Look at the circuit running out to the water feature. If the pump doesn't trip a different GFCI circuit then I think something is wrong with your pump circuit.

The GFCI looks for an imbalance between your hot and the returned current on the neutral. They are very sensitive by design and trip on something like 4-6 ma.

I would expect the sensitivity be dependent on the individual product - not whether it's panel or outlet type. --tho there may be trend there. (IDK)

^^This^^

Is the circuit to the pump a dedicated circuit with only the pump outlet at the terminus or are there other outlets/junctions along the path? If there are other exposures along the circuit, any one of them could be a contributing factor to an imbalance, once the pump is connected. A minor "leakage" from the neutral to ground anywhere on the circuit path would make the breaker more sensitive to any imbalance produced by the pump, causing the breaker to trip. It doesn't take much as, noted above, the imbalance necessary is only ~6mA.

Would it be possible to remove the breaker, install a standard breaker and then put a GFCI outlet in the outside box instead? I think that would take a lot of wire out of the equation?

That would be an option IF there were no other devices/outlets to be protected along the route from the panel to the pump outlet.

Is it possible that your GFCI circuit is a 15 amp? Maybe when you plug into another outlet its a 20 amp circuit?

Agree with those who say to look at the circuit from the breaker and the pump. Did you just bury a cord to the pump, or is it housed inside a conduit? Sometimes people just bury the wire to an outside pump or whatever and a short can develop over time.

Remember that plugging a different pump into the same outlet/circuit doesn't trip the breaker. I would think that if there was a problem in the wiring between the GFCI breaker to the outlet, that any grounded electrical device plugged into it would cause it to trip. Not just a single pump. I tried plugging two different pumps from the water feature into that outlet -- no problem. Only that one pump.

Which makes me suspect the pump. But, the same pump on an extension cord doesn't trip a GFCI outlet on the side of the house. (At the moment I can only guess that the GFCI breaker is more sensitive, either by design or something to do with the way the circuits are grounded.)


The single circuit branches to three outlets that are in the same box. Each branch is controlled separately -- allowing different pumps to operate independently, but protected by the same GFCI breaker.

I was told by the electrician that local code wants you to have any 110v line in a landscape area to be controlled by a GFCI breaker. Otherwise you could have an issue between the line and the GFCI and hurt someone. (The GFCI outlet might shut off the outlet, but the line would still be hot between the panel & the outlet.)

This has run without issue for over 10 years.

We did just bury the cord. It is a complete waterproof cord, installed on the pump from the manufacturer. I don't think it is user-replaceable.

No recent digging in the area. No crimps. Happened after a long, hot, dry spell. The outlet is about 2' away from where the cord comes out of the ground (it's located in a well containing a filter.)

And....it doesn't trip the GFCI outlet on the side of the house.

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Yet--I'm betting on a developing issue in the pump. It hasn't been run nearly as much in hot weather as it normally runs. I've plugged it in. Will run it constantly for a day or two, then try it again in the original outlet. Maybe there's some condensation causing problems.

But my previous experience with GFCI has been much more straightforward with clear causes.

This is an odd one.

Just a possibility. Just saying I've seen many times when a buried cord has caused a failure. One of those times was my own. Replaced it with the line inside a conduit so that no water/moisture/bugs/ etc. could get in & didn't have a problem after that.

Left arrow points to the "man hole cover" over the filter where the pump is located. Right points to the outlet box.

http://forums.pelicanparts.com/uploa...1440956953.jpg

I don't disagree. But if the cord is bad (for whatever reason), I think the whole pump has to go.

I suppose that if I have to replace the whole thing, I could try just replacing the plug on the end of the cord, first. The cord makes a tight turn there to get into the box.

It's probably a fool's errand. But it might be worth a few bucks just to check before replacing the entire pump.

For all I know, it's some moisture that has built up inside the pump and not the cord itself. Doesn't really matter since I can't separate them.

GFCI trips when it measures a difference in current, 20-30ma. Some of this may be coming from the other wiring on the circuit, and should be measurable with an ammeter. Leakage on the other circuits will add. Chasing ghost trips

Having said that, it is likely the pump(could be the breaker), and the test outlet is less sensitive than the breaker. But I would check the other circuits, or disconnect them and see it pump still trips.

Not sure how old your house is, or how long you've been there, but I'd also test the GFCI outlet that *isn't* tripping. I tag along on 4-5 pre-purchase home inspections a month, and come across a lot of GFCI outlets that don't trip. Sometimes they're old, sometimes they aren't wired right, sometimes they have a GFCI outlets wired onto a circuit that's already GFCI protected... which is apparently a no-no

Good point. It was part of a remodel that added the pumps and the other circuits. It has been operating well for 10+ years. So, this is new. Something has changed. Moisture. Grounding. Something.

I'm quite possibly wrong, but if it were in the base wiring, I think it would trip regardless of which pump you operate through that outlet...not just the one.

I do know that the GFCI that's not tripping is on a regular breaker, not one of the GFCI breakers. So, at least I don't have to worry about that.

Question:

Let's suppose that there's an issue with the cord or plug on the pump that's tripping the breaker.

Would any continuity test at the prongs on the plug reveal that's the problem? Can I look for continuity between two of the wires where there shouldn't be any?

(For example, continuity between the positive wire and the ground?)

Shouldn't a meter reveal what the breaker is reacting to?

I have been told by several electricians that the life span of a GFCI is about 10 years. After this they either trip easily or may stop tripping all together. I have a general comment about this in every report. The same goes for GFCI & AFCI breakers. I have also noticed that in 9-11year old homes there seem to be at least 2-3 GFCI outlets that are not functioning properly.

You need to do a hi-pot test. That tests the insulation to ground at high voltage.

A 'normal' meter test won't show the insulation failure at higher voltages.

Thanks. I did replace the breaker with a new one, and it didn't change anything. So, in this case, it wasn't the breaker.

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Update:
Since the power plug on the end of the cord was the most exposed part of the electrical connection to the pump and the cord had to make a sharp turn due to the shape of the molded plug, I thought I'd try putting on a new plug.

Even though the plug on the end of the power cord looked fine, I cut it off along with several inches of cord. Installed a new plug. I applied a contact sealer to the screw connections for the wires and a silicone sealer to the power cord where it enters the plug.

Tested it 4 times today. The pump came on without incident. No blown breaker.

In some ways, the real test might be tomorrow once the pump has had time to fully cool. I ran it for several hours today on the extension cord. If the real problem is moisture in the submersible pump housing, the heat of operation might have put it into the trapped air inside the pump. But by tomorrow, sitting under water for the night, it should have been cool long enough to condense again (if that's the problem). Will see what it does tomorrow.

But for days, 100% of the time, it blew the breaker when I tried to run it on its regular circuit. And now, 4 times in a row, it's turned on without incident on the same circuit.

With any luck, it was a 10y/o plug that had gotten a little moisture in it or the first few inches of the power cord. Will see.

Thanks for everyone's input!