Two hot wires, two circuits, one outlet

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  #1  
Old 04-25-05, 02:53 AM
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Two hot wires, two circuits, one outlet

When replacing a standard outlet in a bathroom with a CFCI, I found three wires in the outlet box, white, black and red. Both the black and the red are hot and on separate circuits in the panel box in the basement.

The outlet is wired white to silver paired with black to gold, and the red is on gold below the black. The outlet is not switched and the remaining power in the room is not on either of the circuits used by this outlet.

Don't know what to do with the red wire. Can anyone help?

Thanks,
Al
 
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  #2  
Old 04-25-05, 03:23 AM
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This sounds like it could be a multiwire circuit.

Is the tab broken between the two halves of the original receptacle?

If this is a multiwire circuit, be very careful. They can be confusing. You can easily damage your electrical devices and/or create a very unsafe condition.
 
  #3  
Old 04-25-05, 05:09 AM
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Sorry, but I do not know what you mean by the tab being broken.

The original receptical is pretty old (house was built ~ 1955). The black and red wires are connected on the same side of the receptical and there is no separation in the brass colored plate to which these two scews are attached.

Hope I have not confused you with this reply.

Thanks for you help.
Al
 
  #4  
Old 04-25-05, 05:22 AM
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The old outlet was split-wired (but perhaps not correctly). You cannot split-wire a GFCI. So just cap off the red wire with a small wire nut and don't use it. If that doesn't work properly, or something else stops working when you do this, post back and tell us what happened.
 
  #5  
Old 04-25-05, 05:23 AM
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Regular duplex receptacles are designed such each of the individual receptacles can be powered separately. A common uses for this would be for having a light switch control half a receptacle, allowing a clock (for example) to use the other half of the receptacle.

There is a small metal tab which physically connects the two plates behind the screw terminals on each side of the receptacle. The tab is designed such that it can be easily broken with a pair of pliers.

Very carefully examine the receptacle you removed. Use an ohmmeter if you are unsure of the two screw terminals are connected or not.

What else is controlled by these two breakers? That may help us determine what the wiring is supposed to accomplish. Also, are these breakers adjacent to each other in your panel? Are they on the same half of the incoming 240 colts service (that does NOT mean are they on the same half of the panel)? When you measure the voltage between the black and the red wires, do you get 0 volts or 240 volts?
 
  #6  
Old 04-25-05, 05:25 AM
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cut off the breaker with the red wire. If you don't lose power anywhere else in the house then remove the wire from the breaker & cap it off. Put a label on it (spare to bath circuit). cap off the wire in the recept box.
If this breaker does feed other outlets in the house then leave the wire on the breaker, cap it off in the recept box and label it circuit #(whatever number is beside the breaker)
 
  #7  
Old 04-25-05, 07:01 AM
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Thanks all for the info.

Here's what I can tell you now. The two breakers are on the same side of the panel and are separated by one other breaker between them.

I had tried the GFCI outlet using only the black and white wires and it checks out Ok.

I will take a closer look and let you know what I find. Thanks again.
 
  #8  
Old 05-02-05, 12:01 AM
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After checking the panel I found that the second line running to the outlet is the only thing on that breaker. As advised, I capped it off and marked it for future reference.

Thanks again to all for your help.
 
  #9  
Old 05-02-05, 12:47 AM
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"The two breakers are on the same side of the panel and are separated by one other breaker between them."

If this was the case, and there was only one neutral then you had a very unsafe condition, which could have led to a fire. It's a godd thing that you fixed the problem.
 
  #10  
Old 05-02-05, 01:06 AM
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Originally Posted by racraft
"The two breakers are on the same side of the panel and are separated by one other breaker between them."

If this was the case, and there was only one neutral then you had a very unsafe condition, which could have led to a fire. It's a good thing that you fixed the problem.

That's what I thought too. However, I did think of one possibility where it would've been a proper multi-wire (at least so far as the neutral is concerned), and that is if at least one of the breakers was actually half of a tandem breaker, and that the "breaker in between" was actually the other half of that same tandem. However, that still would've been inappropriate for this application as the two halves of the multiwire were on the same yoke...handles should've been tied to force a common trip.

The more I read on this forum, the more I understand why the experts here *rarely* recommend a multi-wire circuit. They can get confusing quick.
 
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