Can "wattage" trip a GFCI?

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wrote:

I forgot to include my tag line......... If you can't dazzle them with brilliants, baffle them with bullshit.
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wrote:

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On Jan 16, 4:23 pm, snipped-for-privacy@snyder.on.ca wrote:

Unbelievable. People are actually replying and answering this stupid question without apparently even realizing that the question already answered itself. Did it not state: ""The two insulated wires each carry 120 volts, but they are 180 degrees out of phase "? Beyond that, it wants a yes or no answer to something that is mutually exclusive, ie "In phase or out?" How the hell do you guys answer that with a yes or no?
The problem some of you are having is understanding the difference between what something may be commonly called by those in the trade and the engineering concepts and definitions of systems, phase, etc.
And in the case of 240V service in your house, the answers you seek are:
Q What is the phase relationship of the two hots? A They are 180deg out of phase with each other
Q Does it matter how that phase difference was achieved? A No, from an electrical engineering perspective, we just need to look at the voltage waveforms and current flow on the service cable. Plot the waveform on a graph paper and you have your answer.
Q Is this commony called a two phase system? A No. Probably because it's created by a transformer that uses one of the three phases generated by the power plant.
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On Mon, 17 Jan 2011 06:47:54 -0800 (PST), snipped-for-privacy@optonline.net wrote:

It was defined to me some 30 years ago, but what I came away with was that it is "in phase" if the voltage and current reach peak and 0 at the same instant. That is what I understand a single phase transformer does. (Ignore capacitance and inductance)
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What you are talking about is the relationship between voltage and current. If I put capacitance or inductance in a linear system, it changes the phase between the voltage and current. So, as you put it, they don't reach peak or zero at the same time. When plotted, the current and voltage are out of phase by a certain number of degrees. Whateve that shift is, you can describe it in degrees.
The phases under discussion here are pure voltage waveforms and are present without even having a load. With a 240V service, you have identcial sine waves which are mirror images of each other, between either hot and neutral. Take a sine wave and shift it by 180deg, ie one half cycle, and that is exactly what you have. So, you have two voltage waveforms that are 180 deg out of phase with each other. Hook up an oscilloscope and you can see it. Yet some are arguing that this then just becomes "it's just a negative", it's a case of plus and minus, etc. and can no longer be described as two phases which are 180 deg out of phase. Yet, there they are on an oscilloscope. Maybe someone can tell us this:
I can see these two distinct phases on those 3 wires of the 240V service with an oscilloscope. With 3 phase, I could do the same thing on that service and see 3 different phases, each seperated by 120 deg. Why is it that in the latter case, those on the other side of the argument here say there are 3 phases present, but in the former, there are but one, not the two on the oscilloscope? Posters dpb, Jeff and David and myself would describe both those services, their phases, in a consistent, logical manner.
Usual disclaimer: I did not just say, nor have I ever said that a 240V service is called a two phase service.
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David Nebenzahl wrote:

I have no idea where I read that thing about electrons just jiggling in an AC circuit. Curiosity got the best of me so I snooped a bit. These popped up: http://tinyurl.com/4pgadee http://tinyurl.com/4ct2pqu

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On 1/15/2011 6:37 AM Dean Hoffman spake thus:

OK, that's interesting; thanks. I'd never read that explanation. (I'd sooner trust the BPA article than that online forum that seems to have a lot of clueless, unscientific types posting to it.)
So what they're saying is that, basically, even though electricity moves at [about] the speed of light, electrons actually move very slowly. Verrrrrry slowly.
But that doesn't change the fact that in both DC and AC, *current* flows, almost instantaneously in both cases. It's just that current doesn't necessarily coincide with electron motion.
(I have no idea now how electron and current flow actually works, but again, that's at the quantum physics level. Us boneheaded electricians can still go on thinking that AC currents flow, not "jiggle".)
--
Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
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On 1/12/2011 2:27 PM, DerbyDad03 wrote:

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

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*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.
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FYI..in our latest exchange he said that he has already swapped out the GFCI and it didn't help.
His final answer was "I no longer do much work that requires a high wattage worklight, so I gave up chasing the problem. My underpowered incandescent rough duty bulb is enough."
What are you going to do...
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You can test a socket say, by plugging in another device. How about a heater less than 1500 watts.
You can also try measuring resistance to ground on either line input on the plug. It should be megohms or higher. Try also working the switch. Its possible to buy breakers with GFI's, but they are usually in the main household box.
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Heck, I bought a 500 watt single tripod lamp at my local hardware for $20. It has a two position switch for brightness. They get some nice deals. Also make sure ground is connected to the metal stand, but that's just a safety issue.
greg
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On Jan 18, 7:51 pm, snipped-for-privacy@snyder.on.ca wrote:

It may be critical to the convention of what that 240V service is commonly called, but it doesn't alter the fact of how many distinct voltage waveforms are present. Going back to your example of the simple circuit with two balanced loads connected across the 240V hots, yes, in that case, you have only one phase. I cannot hook up an oscilloscope and see anything but one sine wave. As soon as you introduce the neutral, now I can see TWO different sine waves relative to the neutral, one being 180deg out of phase with the other. That circuit can now be described as having two phases.
Suppose I take a black box that consists of various linear circuit components and is powered by a 120V AC outlet. Inside that box, I have a common reference point. I ask students in a first year electrical engineering course lab experiment to graph the voltages at circuit points A, B, and C relative to the common reference point. I have the circuit designed so that the waveform at point B lags the one at A by 30 degrees and the waveform at point C lags the one at A by 180 degrees. I ask thefollowing questions:
What is the phase relationship between waveforms A and B?
What is the phase realtionship between waveforms A and C?
How many different voltage phases are there in the black box at points A, B, and C?
Do I need to know exactly how the voltages were generated, whether it came from a wall outlet, battery/inverter, trnasformer etc to answer any of those questions?
What is your answer? Is it that there are 3 phases or is that there can be only one, because it's originating from an outlet that has only one phase?
If your answer is that there are 3 phases present, then continue to the next part. I have another black box that merely consists of the 3 wire 240V service. The common reference point is the neutral, point A is one hot, point B, the other hot.
What is the phase relationship between waveforms A and B?
How many phases are present?
Note the usual disclaimer. I did not just say, nor have I said that the 240V service is commonly called two phase.
It's like I said earlier. If I went around telling people my son is a homosapien, or if I referred to water as dihydrogen oxide, it would be unusual and cause much confusion, because a lot of people wouldn't even know what it means. But that doesn change the fact that technically those definitions and terminology are correct.
Also, Bud's argument asking to find a center tap transformer manfacturer that calls their transformer two phase doesn't prove anything. I could just as well ask to find a capacitor manufacturer that says their capacitor can generate a 90deg phase shift.

This makes no sense at all. Why do I neeed 2 seperate secondaries? You are getting all hung up on where the power comes from. The mere presence of two voltage waveforms that are of different phases in a circuit, readily visible on an oscilloscope, is all that it takes to have two phases present.
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On Sat, 22 Jan 2011 08:54:39 -0800 (PST), snipped-for-privacy@optonline.net wrote:

of explanation will get through.
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On Jan 22, 3:30 pm, snipped-for-privacy@snyder.on.ca wrote:

In other words, you won't answer a few basic, straightforward questions about phase that go directly to the core of the discussion, because to do so is impossible without contradicting yourself. I think those of us on the other side of this have answered and addressed all your questions/ issues with no problem.
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