Last week I lost power to my new garbage disposal. I opened the box to find this:

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There are three cables coming in from the bottom. Two of these are somewhere downstream from the Panel, not too sure. The other goes to the garbage disposal.

There is a cable coming from the top, There previously was a switch that controlled the sink lamp. I wired its hot wire through a new switch, now it turns on my kitchen lights instead (The kitchen light already has two other switches that control them). It could have been my mistake.

I'm suspecting this is a MWBC but I'm not very experienced so I don't know how to identify and how to fix. It seems like there are two circuits from the breaker box involved. At the breaker box, the two circuits are not handle connected. How can I trace and diagnose each of the cables in this box?

  • 4
    did you check the reset button at the bottom of the disposal? Are the circuits labeled? Can you provide a picture of your panel labeling and insides?
    – JACK
    Jul 17, 2020 at 12:17
  • 4
    Can you post photos of the insides of the junction box in question, as well as of your panel please? Jul 17, 2020 at 12:28
  • It looks like you intended to include photos, but that they didn't quite make it... Please edit to include them!
    – FreeMan
    Jul 17, 2020 at 14:43
  • I will edit to include photos Jul 17, 2020 at 15:01
  • 1
    I recently had an electrical problem that seemed to involve two breakers that I actually posted about on here. The breakers' handles weren't joined, but the ended up being a multi-wire branch circuit that some idiot connected the ground from to another breaker. My info for you is that 1) a MWBC usually has a black, red, white and green (or bare) wire in the same romex, with the black to one breaker and the red to the other and 2) I ended up getting a tester that told me what breaker belonged to what outlet & 3) advice given to me was open every outlet to find where the MWBC begins Good luck
    – Ron Kyle
    Jul 18, 2020 at 17:36

1 Answer 1


Years ago handle ties were not required. They have been for decades , if you think it’s is a multi wire turn off both breakers verify both hots in your box are dead, you can open your breaker panel and most of the time NMB or Romex is used. There will be a red on 1 breaker a black on the other going to a cable with a ground and a neutral, that would be 100% verification.

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