3 wire Washer circuit?

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  #1  
Old 11-04-10, 01:05 PM
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3 wire Washer circuit?

In the midst of a small laundry remodel, need to move back the outlet for the washer. I thought it was a dedicated circuit but it is odd to me.
120V, 20A from panel, with red, white, black and ground wires.
The white and black go to outlet for the washer along with ground. But what is the red for?

There is another wire leaving the box that I cannot trace, nor can I find what it does anywhere. It is standard 2 wire with ground. This red wire coming from my service panel ties into the black wire and the white wire into the white.

It is original wiring from construction, in 2005.
As I said I can find no outlets, lights, fans etc that it services.
It disappears up into the roof and I can't trace it, (vaulted ceiling)


Anyone know why it would be wired in such a way?
Thanks.
 
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Old 11-04-10, 01:40 PM
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Is the voltage between the red and black 240v? Is the cable connected to a two pole breaker at the panel you may have a multi wire 120v circuit. It is not uncommon. Perhaps what the second circuit served is no longer used. Is the dryer gas or electric? If gas is there an unused receptacle near it.
 
  #3  
Old 11-04-10, 11:04 PM
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I concur with Ray that you must have a Multi-Wire circuit. (find them in every panel in Orange County,Ca.) It's a delight to see them on a Double Pole C/B but that usually is not the case. Main thing is that you have 240v between the red and black. If you have 0V between them and it is indeed a shared neutral circuit, then there is always a potential for fire, if not in 1 day or in 1 month or in 1 year, then perhaps in 20 years. Perhaps the unknown branch circuit goes for some outdoor usage that you are not aware of??? If you cannot find it's location, you could just disconnect it, either at the panel or at the location at which you are working. P.S. perhaps the unknown circuit is for the home alarm system or such?? Don't want to disconnect that.
 
  #4  
Old 11-05-10, 09:29 AM
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Yeah, after more research it is a multi-wire circuit. I was confused because I couldn't find anything else without power when I opened the breaker.

Taking the cover off the main made it clear that they are shared neutrals. I discovered the 2008 NEC requires double pole breakers, but of course I do not have them since house was built in 2005. Probably because people were getting shocked, when they thought the power was dead and were too lazy to drag their meter up with them to verify.

I actually have three circuits like this. At least they all appear to be done correctly. I do have 240V across them.
Marked the circuits in the panel as shared neutral so I would remember next time.

I can see how the idea is nice for saving material and labor costs, but after reading up on on the problems they can cause, I think its a poor choice for safety reasons.

Thanks for the quick responses.
 
  #5  
Old 11-05-10, 09:48 AM
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Originally Posted by kirsch92 View Post
Probably because people were getting shocked, when they thought the power was dead and were too lazy to drag their meter up with them to verify.
That's essentially the reason.

I actually have three circuits like this. At least they all appear to be done correctly. I do have 240V across them.
Marked the circuits in the panel as shared neutral so I would remember next time.
Sounds like a good plan. It's unusual to see MWBCs that often in modern construction.

I can see how the idea is nice for saving material and labor costs, but after reading up on on the problems they can cause, I think its a poor choice for safety reasons.
They're not bad when done correctly, the problem is untrained people modifying them in unsafe ways. Now that you know what you're dealing with you should be fine.
 
  #6  
Old 11-05-10, 05:36 PM
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My house was built in 1987 and it has (had) at least five MWBCs. In fact, I think the ONLY circuits that weren't MWBCs were the small appliance circuits in the kitchen and the 240 volt clothes dryer circuit. None of the MWBCs were connected to two-pole circuit breakers and I don't even think they were all connected to adjacent circuit breakers. This house had the absolute bare minimum of branch circuits to meet code and even the home inspector was surprised to see so few circuits.

I have since re-wired several of the MWBCs, added several more circuits, grouped the circuit breakers on the remaining MWBCs and added handle ties to those MWBCs.
 
  #7  
Old 11-05-10, 09:18 PM
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Furd,

My last house was built in 1980 and I decided to replace the main because I had no extra breaker spots available. I had never heard of the brand before, and when I looked it up on the internet, the only hits were fire marshal reports on all the fires they had caused.

Moved that project to the top of the list.

Thanks for all the help everyone.
 
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