220V dryer sparked on startup (3 wire) What to test?

Page 14 of 16  
On 11/16/2013 10:44 AM, Stormin Mormon wrote:

I remember something about a ground connection being no more than 1V from true ground. According to that definition, the third wire could be ground.
Then neutral is a grounded current carrying conductor. This wire is neutral too.
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The proper term is grounded conductor, and it is white. The grounding conductor is green.
White carries device current/current imbalance. The green/bare wire equalizes potential and provides a dedicated fault path for the circuit breaker in case there is a short to any bonded (to ground) metal surface/raceway where the conductors are present.
There is no such thing as a neutral in a single phase application.
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On Sat, 16 Nov 2013 13:40:02 -0600, Nightcrawler® wrote:

Interestingly, mine has a white wire going to a green bolt.
http://farm3.staticflickr.com/2869/10891120223_3aa4c91eba_o.gif
:)
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It is wrong of them to do this, but I guess some moron engineer thought this would not confuse someone, though in this application I do not see how. In a hard wired installation, yes. Still wrong. Bonding jumpers are to be green/bare/yellow with green stripe if you are into non-American color coding.
That wire still needs to be terminated, or have a separate wire, terminated to the center terminal. This will be your chassis ground or what is called a bonding jumper.
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Danny D'Amico wrote:

Hi, I think simply white always carry current. green is safety in case some thing happens to white wire(connection) Every thing we touch should be at ground level all the time.
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On 11/16/2013 1:40 PM, Nightcrawler® wrote:

The term "grounded conductor" works in the NEC where people eventually figure out the difference between "grounded" and "grounding".
"Grounded conductor" is stupid in this newsgroup.
And the NEC finally put in a definition for "neutral conductor". "Neutral conductor" is a "proper term" for the white supply wire.

Nonsense.
A 3-wire residential service is single phase and the neutral carrys the current imbalance. It is also a "neutral conductor" by the NEC definition.
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On 11/16/2013 05:31 AM, Stormin Mormon wrote:

I'm looking at the receptacle chart at www.repeater-builder.com/tech-info/pdfs/nema-non-locking.pdf
The normal three-wire dryer receptacle appears to be on line 10 (125/250V). This receptacle has 2 hots and neutral. This is different from line 6 (250V with ground).
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On Friday, November 15, 2013 7:58:24 PM UTC-5, snipped-for-privacy@attt.bizz wrote:

Nonsense. 180 deg out of phase and opposite sign are the same thing. Hook up a scope and you'll see.
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On Sat, 16 Nov 2013 09:37:19 -0800 (PST), " snipped-for-privacy@optonline.net"

Wrong. I thought you were an engineer.
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On Saturday, November 16, 2013 12:49:33 PM UTC-5, snipped-for-privacy@attt.bizz wrote:

Then instead of just saying "wrong", why don't you explain the difference?
Test question:
A graph of three sine waves is given, A, B and C, B is shifted 90 deg from A. C is shifted 180 deg from A and looks like it's opposite.
Question:
1 - What is the phase realtionshiof B to A?
2 - What is the phase realtionship of C to A?
My answer to 1 is B is 90 deg out of phase relative to A.
My answer to 2 is C is 180 deg out of phase relative to A. To a lay person, it could also be called it's "opposite".
How those waveforms are derived, what else you call them in a particular application, doesn't change the fact of what they are and their relationship to each other. There are many ways that such voltage waveforms could be generated. It doesn't change the fact that in a 240V residential service the two hots are in fact 180 deg out of phase realtive to each other.
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On Sat, 16 Nov 2013 10:50:51 -0800 (PST), " snipped-for-privacy@optonline.net"

You claim to be an engineer. You should know better.

For the simple degenerate case of a pure sign wave, they'll look the same. That is *NOT* the general case and that is not how the words are defined.
<irrelevance snipped - though I should snip everything you write>

Words mean things. You can use them to lie all you want but I'll call you on it.
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On Saturday, November 16, 2013 2:01:29 PM UTC-5, snipped-for-privacy@attt.bizz wrote:

es

a

ees

So typical. Instead of writing a few sentences to try to explain your case, you start with the insults. That's because you have no case.

How is a sine wave, which of course is exactly what AC power is, a "degenerate case"? And they don't look the same, they have a "phase" relationship, expressed in degrees to each other.

Yes, because you refuse to look at anything that shows you're wrong.

Is wikipedia lying too:
http://en.wikipedia.org/wiki/Split-phase_electric_power
A split-phase electricity distribution system is a three-wire single-phase distribution system. It is the AC equivalent of the original Edison three-w ire direct current system. Its primary advantage is that it saves conductor material over a single-ended single-phase system while only requiring sing le phase on the supply side of the distribution transformer.[1] The two hal ves are 180 degrees apart with respect to center point.
Read the last sentence. They are saying exactly what I, Mark Loyd and at least one other person have been telling you. And that is that the two hots at the dryer are 180 deg out of phase with each other.
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On Sun, 17 Nov 2013 05:55:13 -0800 (PST), " snipped-for-privacy@optonline.net"

Because a single frequency sine wave is symmetrical, both forward and backward, and top to bottom. Add some distortion (which is always present in the real world) or delay and your gross simplification falls apart. Inverting and phase shifting are entirely different things.

You're some piece of work, Trader. You can't admit that you're wrong *IN ANYTHING*. Even though you claim to be an EE, you're wrong. Get a refund. Invest in Cracker Jax. It's better than your degree.

What do they say about scientology?

They're wrong.

They're wrong.
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On Sunday, November 17, 2013 11:55:12 AM UTC-5, snipped-for-privacy@attt.bizz wrote:

Good grief. Are you for real? Now you're going to claim that if we hook up two inputs of a scope to the two 240V hots, the waveforms are going to be so far different from perfect sine waves that the phase relationship can't be determined? It doesn't fall apart at all. You could have a sine wave and a sine wave with lots of noise on it. As long as they are recognizable as oscillating waveforms with the same freq, it's entirely appropriate to ask what the phase relationship is between them. And in this case the relationship is that they differ by 180 deg.

se distribution system. It is the AC equivalent of the original Edison thre e-wire direct current system. Its primary advantage is that it saves conduc tor material over a single-ended single-phase system while only requiring s ingle phase on the supply side of the distribution transformer.[1] The two halves are 180 degrees apart with respect to center point.

I see and your reference would be?

I see, and your reference would be?
Here's another reference, an app note from an electrical eqpt manufacturer, the describes split single phase:
http://www.behlman.com/applications/AC%20basics.pdf
"The two legs, represented by Phase A and Phase B, are 180 degrees apart. "
Bingo. Exactly what Mark and I have been saying all along. Hook up a scope and see. Or dig your hole ever deeper as usual, your choice.
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On 11/16/2013 12:50 PM, snipped-for-privacy@optonline.net wrote:
[snip]

I think the people who are denying that it (residential 120/240) is 2-phase are considering the (1-phase) connection to the transformer primary. You still have 2 phases inside.
You could be using 2 120V transformers (primaries in parallel, secondaries in series with ground between then), a generator with a 2-phase (180 deg apart) output, or even 2 120V (synchronized) generators. You still have 2 phases.
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This single phase/two phase thing is almost as bad as the WD40 threads.
In the normal house at the pole (on the ground or where ever) the secondary is a center tapped single phase feed to the house. There is very little 2 phase in the US. What is on the other side of the transformer going back to the power company does not mater at all. The transformer converts it to a center tapped single phase feed to the house.
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On Sat, 16 Nov 2013 15:28:26 -0600, Mark Lloyd

No, that's wrong. You only have one phase. It is split into two legs. Words mean things.

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On Saturday, November 16, 2013 6:20:01 PM UTC-5, snipped-for-privacy@attt.bizz wrote:

Yes, words mean things. And the term "phase" is a term widely used in math, physics, engineering. In the context it's being used it only means the relationship between two waveforms that are present at the 240/120V dryer connection.
If you were in school and they hooked an oscilloscope with two inputs up to:
Dryer hot 1 and neutral Dryer hot 2 and neutral
and showed you those waveforms, only calling them waveform A and B and asked what the phase relationship was between them, what would your answer be?
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On Sat, 16 Nov 2013 17:02:48 -0800 (PST), " snipped-for-privacy@optonline.net"

Ah, an appeal to "authority". You're wrong, Trader. The two (180degrees out of phase, and inversion) may look the same but they most certainly aren't,

They are opposite.
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On Sunday, November 17, 2013 11:57:03 AM UTC-5, snipped-for-privacy@attt.bizz wrote:

And again no explanation to support the claim at all.

What a joke. So, if they differed by 170 degrees, or 190 degrees, what would the relationship be then? Almost opposite? You can't get it in your head that 180 deg phase difference is just one special case of a relationship of waveforms. How specifically they are generated matters not a wit. And for the record, saying they differ by 180 degrees is what one would expect from even a high school math student as opposed to the imprecise "opposite".
Here is an app note from an electical eqpt manufacturer that explains 240/120V split-phase:
http://www.behlman.com/applications/AC%20basics.pdf
"The two legs, represented by Phase A and Phase B, are 180 degrees apart." Since they are 180 deg apart, wiring them together with their relative polarities will result in.... 240V"
Notice that they acknowledge:
There are two phases, A and B. They differ by 180 deg in phase.
QED.
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