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I am finally getting around to replacing an old receptacle in my kitchen. The top half of the receptacle has never worked since I moved in.

Taking the receptacle apart, I think the outlet circuit is a 3 wire conductor going to a 15A tandem breaker. There is no voltage across the red and black wires. There is 120v on each wire to ground. Since the tandem is in a single slot on my breaker panel, I will assume the red and black are the same phase.

I am hesitant to reconnect it as I do not want to overload the neutral. Can anyone help? Should i just cap one hot wire and turn off one of the breakers? Can I connect the red and black wire together, will this prevent the overload of the neutral?

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  • If I understand your description, which is slightly confusing, then you are correct. Feeding the two halves of the outlet from the two breakers can allow as much as 30A to flow through the neutral. - Perhaps the guy who wired it thought the red and black were on different phases.
    – A. I. Breveleri
    Jun 16, 2017 at 5:15
  • BTW I never wire the top and bottom halves of an outlet on different phases, because that means 240V is present in the receptacle (between the small slot of one outlet and the small slot of the other) which may not be rated or properly insulated for that voltage.
    – A. I. Breveleri
    Jun 16, 2017 at 5:21
  • You've got the right idea, just cap off the red wire at both ends, and leave one breaker in the tandem unused. - Note, though, that you'll have a 15A circuit, so don't install a 20A receptacle (with the T-shaped neutral slot).
    – A. I. Breveleri
    Jun 16, 2017 at 5:36
  • Typical error with an MWBC, wiring it to a duplex breaker. possibly the duplex was retrofit to free up spaces.
    – Harper - Reinstate Ukraine
    Jun 16, 2017 at 6:30
  • So are you putting in a new duplex receptacle? If so and you don't need two independent receptacles, then you could just cap one of the wires (red or black) and not use it, but that wire would remain hot unless you turn off its breaker. Does the tandem breaker allow manual turning off of one circuit while leaving the other one on? What brand of electric panel do you have and how full is it? The reason I ask is you could replace the tandem breaker with a 2-pole breaker and use both red and black wires, but you cannot put the 2-pole in the same place as the tandem.
    – Jim Stewart
    Jun 16, 2017 at 9:29

2 Answers 2

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On the old receptacle were the break-off tabs connecting the contacts on the hot side of the two receptacles removed? What about the break-off tab on the neutral side--was it removed or in place? If you just want to use only one hot (red or black) to power both receptacles of the the duplex receptacle, then on the new receptacle, don't break off either of these connecting tabs.

But if you would want to power the two receptacles independently using one neutral (i.e., a MultiWire Branch Circuit (MWBC) using both red and black and the one white), you must put in a 2-pole breaker and put it in a different spot than this tandem breaker. This might require rearranging the breakers in your panel. If you would try to insert a 2-pole breaker in the same location as this tandem breaker, I believe you would find that the 2-pole would not snap into place. It is that way on my GE panel and I think this is a universal requirement.

And on the new receptacle you would remove the break-off connecting tab on the hot side, but leave the tab on the neutral side intact. (You have only one neutral and you want it to serve both receptacles.

In any case do not connect the red and black wires together. You either abandon one of the hots and cap it or, if you use a MWBC, you connect each hot to "its own" receptacle.

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  • I'm guessing you have a Q-line panel which allows half-width 2-pole breakers to be placed centered in two spaces, with a half-width single breaker on each side. Most panels don't let you do that and require you to go for a quadplex.
    – Harper - Reinstate Ukraine
    Jun 16, 2017 at 18:16
  • Yes I have a 47-year-old GE panel which takes those Q-line breakers which are 1/2" wide. I have often wondered why if GE could make breakers like that, that others didn't do so as well. Are modern panels by GE made this way or did the industry go to 1" wide breakers?
    – Jim Stewart
    Jun 16, 2017 at 18:40
  • Patents, I'm sure, plus the fact that most panels' busbars do not lend themselves to having 2 breakers tap them on the same nub. CH couldn't do it, plus, they are 3/4" wide. 3/4" has proven to be a disaster owing to modern tech like AFCI or GFCI and difficulty/cost of cramming it into a small space.
    – Harper - Reinstate Ukraine
    Jun 16, 2017 at 19:31
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So what happened is...

The builder originally, cunningly put a multi-wire branch circuit (MWBC) there, so he could power the two halves of the receptacle from two different breakers. He used a 2-pole breaker or two singles tied together.

Then, the service panel got full. To make more room in the panel, somebody changed out a bunch of single breakers for double-stuff breakers. When he came to this 2-pole MWBC, he ignorantly moved them to a 1-pole double-stuff without even knowing what that is or what it means. And indeed, be double-booked the neutral as you suspect.

As much of a wire-saver as the MWBC is, you don't want it. There are two problems with this: first, you have 240V that close to water, and second, you will want a GFCI on a kitchen circuit, and GFCIs capable of supporting MWBCs are expensive and not available in double-stuff.

The root problem is the panel is full.

This sort of hacked mistake/compromise is one of several things that makes too-small panels dangerous. Another is the impossibility of fitting AFCI and GFCI breakers. I am famous for wildly oversizing panels, I'm not being funny - my goal is to avoid problems like these.

The quick fix

The path of least resistance is to nut the red and black together in the service panel and pigtail it to the same exact breaker, i.e. One half of a tandem. (Or if your breaker is legal for 2 wires, there you go.) This is not paralleling as long as the tab is broken off on the receptacle. (If someone ever changes the receptacle and forgets to cut the tab, different deal, now you're paralleling.)

This solution will play nice with GFCI breakers.

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