Can "wattage" trip a GFCI?

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I was discussing worklights with a friend. I told him that I have one of these 500 watt units:
http://www.harborfreight.com/500-watt-dual-head-halogen-shop-light-40123.html
In one email he said:
"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?
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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).
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***
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!
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Regardless if his wattage is pure or polluted, it's current imbalance that trips GFCI devices
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On Wed, 12 Jan 2011 11:27:33 -0800 (PST), DerbyDad03

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.
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?

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.
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DerbyDad03 wrote:

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.)
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On 1/12/2011 2:27 PM, DerbyDad03 wrote:

Actually a good question.
GFCI's do not work like fuses:
http://home.howstuffworks.com/question117.htm
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Frank wrote:

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: http://tinyurl.com/4dv2hch just above the watt hour meter.
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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.
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David Nebenzahl wrote:

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.)

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On Wed, 12 Jan 2011 20:02:11 -0600, 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.
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Metspitzer wrote:

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. "
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On Wed, 12 Jan 2011 20:54:48 -0600, Dean Hoffman

They are in phase, and opposite polarity. I don't even know what that means anymore..........Never mind :)
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On Wed, 12 Jan 2011 20:54:48 -0600, Dean Hoffman

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.
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snipped-for-privacy@snyder.on.ca wrote:

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.
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On 1/12/2011 10:21 PM, snipped-for-privacy@snyder.on.ca wrote:

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:
http://www.energyquest.ca.gov/how_it_works/transformer.html
Jeff
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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.
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wrote:

Actually, both views are correct. Regardlesss of how the phase difference is generated, if you view the two legs of a 240V service on an oscilloscope the two voltages are in fact 180deg out of phase with each other. Note that the post that generated the discussion did not even call it a two phase system. It only said the two voltages in a 240V service are 180 deg out of phase with each other. That is correct. If they showed that picture on a EE test and asked "What is the phase difference between the two signals, what would you answer have been?"
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On 1/12/2011 7:22 PM Ralph Mowery spake thus:

No, I had never really known what they were until now. Just looked it up, and it's just as you say.
I'm wondering, though, just how effective or even useful 2-phase systems really were. If you graph the waveforms, you see that there's a hole in it, a "missing" phase, the one that would start at 180 that's present in a 3-phase system. So what you have is current pulses that go "bump-bump (pause)" instead of "bump-bump-bump", right?
Apparently that's one reason that 3-phase superseded 2-phase power. It's true that 2-phase was better than single-phase for running certain types of induction motors.
It's a matter of semantics, I know, but the 120+120$0 system we've been discussing actually is a 2-phase system, even though it's not really called that. One side is 180 out of phase with the other side, so by definition you have a 2-phase system.
Hopefully the previous poster who brought this up and was confused by this is less so now.
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