Washer wiring

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  #1  
Old 01-07-07, 04:21 PM
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Washer wiring

I had attempted to move an outlet for my clothes washer today, and ran into a problem that I guess I'm glad I found. I just don't know how to fix it. I expected the outlet to be a dedicated, end-of-the-line circuit. Instead, there were two sets of wires, a 12/3 and a 12/2. The blacks were threaded together, and did not go to the outlet. The grounds were threaded together, and ran to the outlet. The same for the whites. The red from the 12/3 went into the outlet on the opposite side of the receptacle. The receptacle was not modified to have the top and the bottom outlets on separate circuits.

I say that because it seems that two independent circuits are feeding this receptacle. I have the breaker off for "washer" and the washer was indeed not working when I unplugged it. I checked under the house (crawlspace), and the 12/2 wire runs to other outlets in the kitchen. While the breaker was still off tonight, I tested the wires, and current is still running between the white wires (SPARKS) which was unexpected. So...

I have exposed and can easily work with both sets of wires. I would like to leave an outlet where the washer is now, so I guess I can leave the 12/2 connected to the outlet there, as an end-of-the-line outlet. The other wire (direct line, supposed to be just for the washer) can then be moved, but what do I do with the red wire?

Brian
 
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  #2  
Old 01-07-07, 04:30 PM
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Not sure, sounds like a multiwire circuite with a shared neutral
 
  #3  
Old 01-07-07, 07:39 PM
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which cable - 12/2 or 12/3 - comes from the panel?
 
  #4  
Old 01-07-07, 08:54 PM
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This is a multi-wire circuit. Assuming that the black and red wires are from opposite legs of the incoming 240 volts, this is safe. Do not attempt to modify this circuit until and unless you learn about and fully understand multi-wire circuits.

This multi-wire setup should have been properly documented in your panel. I assume it is not. A normal mapping of the circuit would not discover a multi-wire circuit, so it is okay if you did not know about it. Please mark it now in your panel.

As soon as you opened the box and discovered an extra wire, you should have immediately stopped and determined that there was still power to the box. You could have easily killed yourself.
 
  #5  
Old 01-08-07, 10:31 AM
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Not to flame, but honestly how dangerous is 120 volts or rather 20amps (which this probably should be, as it is a dedicated laundry circuit).

The electrician that upgraded my service stood on a fiberglass ladder, wearing tennis shoes, and he touched the service wire. Not the insuation, the wire, demonstrating the fact that he made a lousy ground.

I'm not advocating working live, but other than a nasty jolt, how bad could it be?
 
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Old 01-08-07, 10:46 AM
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If it goes in one hand and out one foot, you may die.
 
  #7  
Old 01-08-07, 11:44 AM
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> honestly how dangerous is 120 volts or rather 20amps

Very. A 5 milliamp shock (0.005A) across the heart is enough to be fatal; it can stop the heart immediately or can cause a heart attack which kills you hours later. That of course doesn't mean that every shock will kill you, but it only takes a very small amount of current in the wrong place.

> touched the service wire

It's like shooting yourself to prove the Kevlar vest works; yes, you'll probably live but it's foolish to take the chance just to prove a point. Service wires are a larger risk than branch circuits, because there often aren't breakers or fuses. An accident can not only electrocute you, but can splatter molten wire metal on your skin and in your eyes in addition to the vision loss caused by the arc flash.

The vast majority of electrocution deaths in North America are caused by 120V sources.
 
  #8  
Old 01-08-07, 01:13 PM
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Originally Posted by racraft View Post
...you may die.
Well that's no fun!
 
  #9  
Old 01-08-07, 07:11 PM
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Smile washer wiring

Turns out that the black wire in the back of the box was a pass-through for a different circuit. It wasn't a multi-wire circuit. The black supplied the kitchen, and the white was acting as a return to the circuit breaker panel, which is why I got sparks. The red was a dedicated line to that outlet, for just the washer. The original electrician used a 12/3 wire to bring two hot wires into the house without needing to run two full cables, then split them to go to different locations. From what I've learned, it's reasonably common.

I pulled the red out of that box, hooked it to a new wire with a shared ground and neutral and ran it to my new washer outlet. I fed the black previously "just passing through" to a new receptacle in the same location (a GFI, which it should have had in the series, but previously didn't), with the kitchen downstream. Did this of course, with BOTH circuit breakers off. All works well.

Thanks

Brian
 
  #10  
Old 01-08-07, 07:28 PM
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Still a multiwire circuit. You need to make sure they share a double breaker for two reasons. 1) For the next guy so he doesn't get hurt 2)If they are on the same lug, that neutral is carrying too much return current to be safe.
 
  #11  
Old 01-08-07, 08:05 PM
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You have created a code violation.

You cannot have a receptacle in in the original location. You must remove it. You can't have one on the kitchen circuit, and you cannot have on on the laundry circuit.

And yes, this is a multi-wire circuit. You should not be attempting to change a multi-wire circuit since you do not understand what one is.

Put everything back the way it was and run a new circuit for the laundry.
 
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