Electrical Shock While Working On Dryer ?

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Hello:
Have the typical Kenmore electric clothes dryer.
While oiling a drum roller underneath, I received a pretty good electrical shock. Really surprising, as I wasn't touching anything other than the frame. Was spraying a bit with WD-40 when it happened. Seemed like such an innoculous thing I was doing, I didn't bother unplugging
Wasn't touching any wires or other parts, to the best of my knowledge. Plenty of room underneath to avoid them.
It was plugged in with the heavy 3 prong 220 plug. I guess one of these prongs is the Neutral, and the other two are for the the two 220 V phases.
Questions:
a. What likely was the reason for the shock ? Could it be a voltage between the neutral and a real ground (thru me) ?
b. Should I run a wire from the dryer case to a good cold water pipe for a ground ?
Thanks, Bob
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3 prong 220Volt plugs are dangerous because if an OPEN circuit should develop in the neutral wire, full voltage can appear on the appliance case...
YES! I would run a wire from the dreyer case to ground on any 3 prong 220V appliance...
I have done that to mine...
Mark
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Mark wrote:

???? How would that happen with just the an open circuit and no other failure?

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Depends on what you mean by open circuit. I wouldn't assume that a dryer that's turned off is consuming _no_ power. It could have electronics that are always on.
As for full voltage on the case, consider: in a three wire dryer/stove connection, the two hots are connected to the elements (thru switching) to provide 240V.
The 120V motor/clock/timer etc. are connected to one hot _and_ the third wire, and the case is connected to the third wire too.
If you cut the third wire between the dryer and the panel, the case becomes live if there's anything switched on on the 120V side.
If the dryer is operating at that point, what happens is that the heaters stays on, yet the timer and motor stop.
Eg: if the motor is switched on, one side is connected to a hot, the other side is connected to a _floating_ (not grounded) case. If you're grounded (eg: touching a pipe, or a grounded clothes washer) and touch bare metal on the case, you get zapped - _thru_ the component that's trying to conduct power (eg: the motor).
I would think most likely that the OP has a neutral/grounding problem.
It's best to kill power to appliances before opening it, even if you think it's totally off and figure you can stay away from the hot side of the switch.
When I had to replace the heating element in our dryer a few days ago, I killed the breaker. I didn't know for sure whether the element switching killed _both_ hots or just one, and I didn't want to find out the hard way. I tested it anyway to make sure I got the right breaker.
[I didn't want to have to move the dryer out to unplug it.]
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Chris Lewis wrote:

Then switch off the breaker or pull the fuse.
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Ahem. Didn't you notice that I said I _did_ switch off the breaker?
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On Thu, 11 May 2006 14:42:44 GMT, "Joseph Meehan"

Many 220V appliances have the case "bonded" to the neutral. If the neutral opens, voltage can appear on the cabinet. I doubt it would be 220V though, more likely 120V through the motor or some other 120V circuit inside the unit that taps one leg and neutral as it's current source.
Newer homes are wired with 4 wire 220V outlets to prevent this, that way both the neutral and ground wires have to open before this could occur.
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It essentially _can't_ be 240V. The only way you can get hit with a 240V shock is if you touch both legs of the main simultaneously. The highest voltage (normally! ;-) available in a house is 120V relative to ground.
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yes, by full voltage I meant 120 V (not 240)V...
Mark
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JK wrote:

I did not know that. It sounds like a bad idea to me.

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wrote:

...
Actually, I don't think it's true. Neither UL nor CSA have allowed anything like that for over my 35 year's experience, and the current rules, including EC definitely do not allow it. An exposed metal part must be either connected to earth, or "double insulated" (which does NOT mean two layers of insulation). The only safety spec number I recall at the moment is the old UL1459 or I could provide more backup. Retired, don't cha know <g>.
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Up until a few years ago, the US NEC permitted stoves and dryers to be connected using three wire connections. Two hots, and a third wire that acts as _both_ a neutral (for 120V loads like clocks and 120V accessory outlets) and for bonding the frame to ground.
Canadian CEC hasn't permitted this for at least 30 years.
US NEC has changed so that it requires 4 wire circuits just like Canadian CEC does. The difference being that the NEC has more "grandfathering" than the CEC does.
In CEC, when you install a new stove or dryer, you must bring existing circuits up to current spec. In NEC, you only have to bring existing circuits up to current spec if you're changing the circuit.
You can't buy a 3 wire cordset in Canada (I don't think we _ever_ required 3 wire outlets. It went directly from 4 wire direct connect to 4 wire outlets). You still can in the US.
Yeah, I think the NEC permissivity was dumb too.
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. . . .

Maybe so, but I don't know of anyone that's been killed by it yet, and what's the point of being a PITA, if it's not going to save lives? Most people change the circut eventually, anyway.
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your right about the four wires, its the code now I believe
wrote:

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There is no neutral in a 220 connection. Two hots, no neutral, and a ground if it is a new enough install.
Yes, I know the really new stuff has a four wire connection that has 2 hots, ground, and now a neutral in case the modern appliance needs 110 volts.
I would check the ground circuit and the case ground with regard to getting shocked. Electricity should not go to the case unless something is wrong. ______________________________ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net

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A stove/dryer is _not_ a 220 connection. It's a 240/120 connection. Stove/dryers have always needed at least three wires to operate.

Stoves and dryers need 110V connections.
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Chris Lewis wrote:

Some stoves (I don't know about dryers) have a transformer to supply 120V to those devices that need it.

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I've never seen one of those. It may be true with some all-electronic stoves. But certainly not anything with a 120V accessory outlet.
Transformers, for anything but very tiny loads, would be more expensive to manufacture than simply providing a fourth wire, or using devices that don't need 120V.
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Chris Lewis wrote:

I would think that is likely true.

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Robert11 wrote:

Interesting question. You prompted me to do a little test and in my test WD-40 did not conduct a current, but it did clean off contacts so that they made a better, lower resistance connection. It made a big difference on the contacts was was checking.
In any case I suggest that everyone make it a habit to unplug any appliance that they are going to open up.

I am not sure of the rule, but I believe that some if not all current three wires plugs for 240 are two legs and a ground. An appliance may not need 120 or it may use a transformer. You may be able to tell by taking a good look at where that third conductor goes and if it is connected to the case.

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