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I had a problem with some switches in the kitchen that controlled ceiling lights. So I opened up all the boxes that were controlled by the 15/17 breaker set.

The only box that had power from the breaker panel also had a switch controlled by breaker 1. All the other boxes controlled by 15/17 were wired in series with this box. When I took a look at the incoming power wire to this box, it was a 3 wire power with red, black and white. Measurements showed R-B 240 V, R-W and B-W 120 V. My conclusion is that I had a multi-wire branch circuit (MWBC). Please correct me if I am wrong, or if I need to do additional tests to confirm this.

From my research, MWBC's are required or strongly suggested to have breakers that have a common handle that controls both the red and black wires. But when I went down to the panel, there was no red wire. I have a picture of the panel below. Breaker's 15 and 17 are in the off position in the picture.

There was a wire for breaker 15, but there was no wire for breaker 17. In addition, there are 2 wires coming out of breaker 1. If I didn't know any better, it looks like someone took the wire out of breaker 17 and put it into breaker 1.

Questions:

  1. Is it OK to put 2 wires into one breaker? My research on the matter is unclear.
  2. Would there be any reason for someone to move the wire from breaker 17 to breaker 1?
  3. Should I move the wire in breaker 1 back to breaker 17?
  4. Any other recommendations are greatly appreciated.

Thanks

enter image description here

Added image from Ecnerwal post

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  • It looks like the extra wire to breaker 1 originally ran to breaker 17. That's why it's shaped the way it is; it was rearranged to go to 1 instead, presumably because there was a problem that needed to be "fixed". Sep 10, 2023 at 17:05
  • Two wires on a breaker might be allowed, but specific for the breaker make. There is a good chance that breaker 17 is bad, the person did not want to play with changing breakers and/or breaker 1 has less power(lights only) used on it than breaker 15.
    – crip659
    Sep 10, 2023 at 17:10
  • The other wire on breaker 1 goes to the clothes washing machine.
    – BPowers97
    Sep 10, 2023 at 17:17
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    Hmmm. But where does the red wire in the box originate from, since both presumed MWBC hots are black at the panel? Curiouser and curiouser.
    – Ecnerwal
    Sep 11, 2023 at 11:42
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    Ecnerwal, your post got me curious as well. So I opened up a box which was above my breaker panel that I had never opened before. Lo and behold, I found my red wire. I added the picture to my original post. The red wire for my MWBC is in the upper right of the picture.
    – BPowers97
    Sep 11, 2023 at 21:52

1 Answer 1

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TL;DR Someone Cheated; Now You Pay

It looks pretty clear that the extra wire on 1 used to be on 17. That is extremely dangerous because:

  • It gets rid of the maintenance shutoff of the two parts of the MWBC together that you had on 15/17. You are fortunate to have handled this carefully so that you didn't get zapped!
  • Two wires on one breaker screw is usually not allowed. (Two wires on a screw-to-clamp receptacle or switch screw is normal. Two ground wires (sometimes 3) on a ground bar is normal. But two wires on a breaker screw? Not usually.)

It seems quite likely that there is a problem with breaker 17. Actually there are some other possibilities - e.g., 15 had an overcurrent which tripped 17 as well (common trip) and rather than solve that problem, they moved the wire on 17 to 1. Impossible to guess.

Replace 15/17 with a double-breaker. This should be a GE THQP220. $16 at Home Depot, may be less elsewhere.

But first check one more thing: Make 100% sure that the red wire going to 1 (which should go back to 17) and the black wire going to 15 are coming from the same cable. If they are from different cables, STOP and upload pictures showing the cables where they enter the panel.

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  • 1
    It looks like 15/17 is already a double breaker (THQP2120), or at least has a handle tie on it Sep 10, 2023 at 22:07
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    Yeah, the correct part is a THQP220, sorry Sep 10, 2023 at 22:14
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    Yeah, you're misinterpreting the picture, it's all QPs there Sep 11, 2023 at 2:31
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    AFCI and GFCI are generally not required (unless they were previously in place) when doing a direct replacement. But assuming these are tandem breakers (QP as opposed to QL) then you can't get AFCI or GFCI for them anyway! For now you just want a straight replacement. New circuits generally trigger the new requirements, but this is a repair. Sep 11, 2023 at 2:41
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    Thank you all. I confirmed that the red wire (see original question for picture) going to 1 and the black wire going to 15 were coming from the same cable with a continuity test. The correct part is THQP220. I made the breaker change and moved the proper wire from 1 to 17. Everything appears all right so far.
    – BPowers97
    Sep 11, 2023 at 22:01

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