Can "wattage" trip a GFCI?

"I like the idea of these lights, but every time I purchase one for use, they trip the GFCI receptacle in my garage. I've had to return every light that I've purchased and have given up on the idea."

When I said that I've used this light in the rain more than once without any problem, he replied with:

"I believe that it's the pure wattage requirements of these lights, more than their quality (or lack thereof) that caused my GFCI to trip."

Does that make any sense?

If it was an current overage the breaker would trip not the GFCI so why would a "high wattage" device trip the GFCI?

Reply to
DerbyDad03
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On 1/12/2011 11:27 AM DerbyDad03 spake thus:

First of all, let's use the right terminology. "Wattage" is meaningless; the parameter that matters here (or not) is *current*. (Remember, P = E x I.) GFCIs are not wattmeters.

So why does the GFCI trip? I dunno:

o Defective GFCI that gets triggered by high currents in both hot & neutral?

o An actual ground fault with the light?

Probably not a very mysterious situation, and easy enough to find the culprit. There's usually a reason for such things; gremlins don't rule the universe (at least not all the time).

Reply to
David Nebenzahl

Regardless if his wattage is pure or polluted, it's current imbalance that trips GFCI devices

Reply to
RBM

If more than one set of new lights causes a trip, I would suggest the existing GFCI may be too sensitive. Changing the GFCI might work.

500W is not a heavy load. It is about 1/4-1/3 max. You could test how sensitive it is by plugging in a drill or a kitchen appliance.
Reply to
Metspitzer

***

That's exactly what I thought (knew!) and that's how I explained it to him. That's why I told him that I have used my worklight in the rain with no issues related to the GFCI. It was after I told him that that he came back with the "wattage" answer.

Well, then that sort of makes the answer to my question a "yes". A high wattage device means higher current and a defective GFCI that can't handle "high" (relatively) current might trip. Semantics?

Possibly, except that he said "...every time I purchase one for use, they trip the GFCI receptacle in my garage. I've had to return every light that I've purchased and have given up on the idea."

I doubt that there could be a fault in every light he purchased. (I'm not arguing...just looking at the facts of this particular situation."

I agree, and I'd have to lean towards a defective GFCI since he said "So, I still bungle about with a trouble light that uses a single, underpowered incandescent rough duty bulb."

I'll suggest that he replace the GFCI and see what happens.

Thanks!

Reply to
DerbyDad03

? "DerbyDad03" wrote

No. Every bathroom built in the past 30 years has a GFCI and most also have

1200 watt hair dryers running off of them at times.

He should check out the light stand and connections.

Reply to
Ed Pawlowski

Take YOUR light to HIS house. If his GFCI trips, one of you has a defective GFCI (probaly his).

A GFCI is not a trivial device - it has real electronics inside. As such, it can fail. Especially if it was made on a Monday or Friday.

(For those not familiar with my alleged sense of humor, that last was a joke.)

Reply to
HeyBub

Actually a good question.

GFCI's do not work like fuses:

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Reply to
Frank

That article might drive the EEs here a little batty. AC doesn't actually flow. The electrons jiggle. I checked a few pages down and found another obvious error. There is another mistake here:

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just above the watt hour meter.

Reply to
Dean Hoffman

On 1/12/2011 5:16 PM Dean Hoffman spake thus:

What, the step-down transformer? What's wrong with that?

And I have to disagree with you; who says AC doesn't flow? During the positive half-cycle, current flows (electrons from negative to positive, or "conventional current flow" in the opposite direction).

I suppose this explanation falls apart if looked at from the POV of quantum physics, but for an explanation of current flow from an electrical standpoint it's perfectly valid.

Reply to
David Nebenzahl

The explanation just above it. The center tapped secondary of a single phase transformer has two phases all of sudden. (I'm growing up to be a picky old fart.)

Reply to
Dean Hoffman

It is considered single phase. If you remove the center tap, you have the same thing on the primary as you do on the secondary.

If you chose to put the secondary tap anywhere but the center, you still have 240 total, but the fraction of 240 changes as you move the center tap.

Reply to
Metspitzer

This sentence is the one that doesn't ring true. "The two insulated wires each carry 120 volts, but they are 180 degrees out of phase so the difference between them is 240 volts. "

Reply to
Dean Hoffman

They are in phase, and opposite polarity. I don't even know what that means anymore..........Never mind :)

Reply to
Metspitzer

There is NO PHASE DIFFERENCE on a center tapped transformer. If the voltages were 180 degrees out, there would be 120 on each side and ZERO voltage across the pair.

Reply to
clare

The common 240 volt system in the US is only single phase. A true 2 phase system will have the the voltages only 90 deg out of phase. In a 240 volt single phase system , the center, neutral or whatever you want to call the wire will carry only the unballanced currents and can be the same size as the other two wires. A true 2 phase system usually has 4 wires, but it it is wired up with only 3 wires, the 'center' wire has to be the largest wire.

There are always some on here that do not understand the differance in a split phase 120/240 volts system ususally used in the homes and a true 2 phase system. I doubt that hardly anyone here has seem a true 2 phase power system.

Reply to
Ralph Mowery

No.

It seems to me that the problem is with the GFCI, or more likely with the wiring.

As mentioned elsewhere, the GFCI looks for an imbalance between the current in the hot and neutral. If those don't cancel it is presumed a current is flowing in the ground, and it shuts down.

My guess is that there is a fault in the grounding somewhere in the garage and that the lamp draws enough current so the mismatch is large enough to trip the GFCI.

I don't know much about these, so that is just supposition. If it were me, I'd look at the neutral connections. Perhaps sub in a regular outlet and look at the voltage drop between known good ground and neutral. But I really don't know, but it is clear that it isn't the light!

Jeff

Reply to
Jeff Thies

Which is exactly what made the little buzzer in my head go off. A single phase can't be out of phase or out of time with itself.

Reply to
Dean Hoffman

I don't think you mean that. Or you have a reference different than the center tap.

If they were in phase (relative to the tap), they would read 0. Same as reading between two breakers on the same phase in a breaker box. It's the same voltage, same phase hence no difference. But of course, it isn't that way.

Put another way: When current is flowing out the top leg of the transformer, it is flowing in the bottom leg. Opposite polarity, 180 out of phase.

I'm assuming that was just a quickie mistake and we won't be arguing this, at least I won't be. I just wanted to correct the record for anyone else.

For others, 240 center tapped is exactly how two 120 phases are delivered into the home:

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Jeff

Reply to
Jeff Thies

*If it is a very old GFI he may be right. Inside of a garage there are large temperature and humidity variations as well as fumes from gasoline and other things that get stored there. The insulation inside of the GFI may have degraded and there may be some internal leakage with a large load. Change the GFI and see what happens. I suggest installing a GFI that is rated for outdoor use. It will have a "W" or "WP" on the label.
Reply to
John Grabowski

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