Wrong! Two hots and a grounded conductor (neutral/white). These types of plugs are often referred as a 120/240. Meaning that it provides both voltages to the device. The new 4-wire plugs do the same thing, but have a dedicated grounding conductor for fault purposes.
As per code, a grounding conductor shall "never" carry any current unless a fault is present; and the only purpose for carrying this current is to trip the breaker. The other purpose of a grounding conductor is to equalize the potential of attached devices to ground, thereby reducing, but not eliminating, the risk of shock.
It sure seemed counter intuitive that the third prong would be neutral, and the device is ungrounded. But, I found a couple web sites that say it is. And says that it bonds the neutral to the frame. Go figure.
Well, thanks for showing me some thing new. I find myself with egg on my face.
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Good thing I've been recently instructed how to apologize.
If it only happens when you turn it on, it wouldn't be static build up. That would have dissipated while it was off.
I'm wondering about some kind of misalignment or wearing out in a two-pole switch. If one side of the 240 is energized ten milliseconds before the other, AND that side is shorted to the shell, AND the shell is not grounded but the vent hose _is_, then this could happen.
And that would be dangerous, obviously. Call a pro. Happy Halloween.
For common house circits there is no real electrical differance in the neutral and ground wires. They both start at the same point in the breaker panel and run parallel with each other to the socket or device that they are connected to. . Mechanically there is often a differance. The ground will either be bare or green and the neutral will be white by the electrical code. They may even be differant sizes.
When used in the 240 volt circuits the 4 th wire ground is just a redundant wire that is connected to the frame of the device . This is an added safety precaution incase for some reason the neutral wire would become disconnected if only a 3 wire circuit was used.
I may well be out of my league, but, I've wired 220 in the past, and, well, *I* used two black and one white (i.e., two hots and a neutral), and it worked, for me.
My problem at that time was that the wiring was in an old house with screw-in fuses, so, that arrangement above would tend to blow one fuse but not the other, which wasn't really a good idea.
I could tell a fuse had blown 'cuz the motor would hum instead of move for the compressor. But, when I replaced the fuse, it would work again.
Dumb. Yes. I agree. Darwin award even? Perhaps. But, clearly, *my* 220 in that case was two hots and a neutral.
I supposed had I two hots and a ground wire tied to the cold water pipe, it would have worked as well.
And, I must note, that I've *followed* the neutral wire, in the olden days, when wires were above ground, from the house, to the pole, to the next pole, to the next (as far as I could tell anyway), until it went straight into the ground.
Of course, I really didn't follow the wire directly, but, I surmised the neutral went into the ground at every third pole. At least that's what I remember surmising way back when ...
So, *both* a ground and a neutral go into the ground. The only difference, as I see it, is that the neutral goes into the ground hundreds of feet away, and it carries current; while the ground goes into the ground at the edge of the house, and, it's not carrying current (unless there is a fault).
So, given all that, I think we're talking semantics here.
I have two hots and this "thing" which goes into the ground a few hundred yards from the house.
Apparently this "thing" is acting both as a ground, and as a neutral. I'm going to check that this "thing" is actually *connected* to the steel case of the dryer and report back!
By the way, the reason (I think) I know that this 'thing' is a neutral (and not a ground) is that it *must* be carrying current.
If the two hots were out of phase by 180 degrees, then we wouldn't need this third 'thing'.
But, three wire distribution along the poles is such that the hot wires are only 120 degrees out of phase (IIRC).
So, if I'm correct, my two hots are 120 degrees out of phase, which means current *must* be going somewhere. That somewhere is this third 'thing'.
Since this third 'thing' is designed to carry current, it's clearly not a ground (since a ground isn't designed to carry current normally).
Now, again, the fact that this third 'thing' goes into the ground makes it 'look' like a ground (to some); but it *must* be carrying current; so, semantically, I wouldn't call it a ground.
Still - I must profess ... this is only how *I* understand the situation; and I may well be wrong (although I think it's this way).
So, I will try to explain what you guys are trying to tell me in the next post (this is too long already).
I think you guys are trying to tell me that this third 'thing' goes from the wall to the dryer innards.
At the same time, it goes to the dryer steel frame!
So, if one of the hot wires were to touch the steel frame, it would go into this third 'thing' and it would go back to the wall.
And, from the wall, it would go to the breaker box; and from the breaker box to the power pole; and from the power pole to another, and finally, a pole or three away, it would go into the ground.
Back at the dryer, that would mean that the steel case of the dryer is attached to the ground by a long wire of a few hundred feet or more.
So, the steel case *could* have a potential on it! (which would be the difference in voltage between the hot wire and the ground a few hundred feet away).
180 degrees, but technically, no. It's opposite sign, not 180 degrees out of phase. ...and it should be 240V (twice 120V).
The timer usually runs off 120V.
The ground is a must, for safety. At one time, it was allowed to run the timer current though ground. A neutral conductor is now required for that current.
Thank you so much for finding that reference for us! I was getting confused, by the conflicting information. This is what my wires look like at the dryer:
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I'll need to go back there and doublecheck that the white wire that is connected to the frame is also connected to that middle (white) wire (neutral?) which is surrounded by two black wires (hot).
to the op caution, this may be dangerous you have read that the 3 prong setup shares the ground and the neutral. so if this shared ground neutral should have a loose wire, this could cause the dryer frame to become energized. and perhaps the metal vent pipe is completing the circuit to ground. that may be why you hear and see sparks. i would not use this appliance again until this is fixed
if you feel you can handle this, do what you suggested, run a heavy wire from the dryer frame to a nearby outlet ground.
after you add a ground , this should make it relatively safe, but get someone to check it before you get shocked or start a fire.
I don't see any provision for a strap from the dryer frame to the center neutral connection for that particular dryer. It would be good to know where that white wire that is under the ground screw comes from.
I have not seen it, but can you give the make and model of the dryer so I can look for a wiring diagram for it ? If you have the book for it, it may have the diagram in it for a 4 and 3 wire hookup.
As someone else said, I would run a wire from the dryer to a ground somewhere.
That green wire needs to be terminated on the center terminal. This will bond the dryer to ground (yes, the neutral). If there is a short you will find out pretty quick.
I could not tell what the other end of that wire is doing, and assumed that it was not terminated. If, by chance, it is affixed someplace else, make a jumper wire that will go under that screw and terminate it on the center terminal.
I have a simple question that might clear some things up. The two hot wires, are they wrapped around a bare cable that is secured at the house and the power pole?
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