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I recently removed an old dishwasher and found some odd wiring behind the dishwasher. There was a cable coming from a switch for the dishwasher, and another random cable taped off with electrical tape just sitting there. I went to try to figure out what circuit the random cable was connected to and found something weird.

  1. ⁠⁠I shut off the breaker for the dishwasher and the random cable has power, but the dishwasher switch does not.
  2. ⁠⁠When I leave that off, and shut off the breaker right under it too, the random cable loses power (as do the outlets above the counter in that area)
  3. ⁠⁠When I turn only the dishwasher breaker back on, the dishwasher switch AND that cable and the outlets get power again.

Is this normal or are wires shorted somewhere that shouldn’t be?

One other thing I noticed, the metal switch cover on the switch box is live according to my NCV when the dishwasher breaker is on. The switch is screwed into the metal cover. I was touching this cover a bunch before I realized this and nothing happened, but does that mean something from the switch is shorted to that metal? Wouldn’t I have gotten shocked if that happened? I switched the breaker off and removed the switch for now.

picture of wiring

picture of wiring 2

picture of wiring 3

picture of wiring 4

picture of wiring 5

picture of wiring 6

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    Turn off all breakers supplying power here. Test, double check, make sure there's no power. Then pull off the box covers and pull all wiring out of the boxes but DO NOT disconnect anything. Get clear, focused, well lit pics of all the wiring (identify which wires/cables are controlled by which breaker) and edit those into your question. That will help people see what you're seeing.
    – FreeMan
    Commented Jan 9 at 12:38
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    I added some pictures of what I see in the switch box and behind the dishwasher
    – Homeowner982747273
    Commented Jan 9 at 15:25

1 Answer 1

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Likely Scenario:

MWBC. There are normal situations, especially with dishwashers, where there is more than one circuit in the same cable. So it is very likely that you do have two circuit breakers controlling the same junction box or cable.

Is this normal

Yes and no. It sounds like your panelboard is missing a required tie between the two breaker handles.

Also, where you said "get power", we need to make sure you're making the correct observation using a multimeter or a plug-in lamp or appliance. Are you really getting power or just setting off the NCV? You're going to get all kinds of confusing NCV results from a MWBC scenario. The NCV will detect electricity unless both circuits are off.

Update on new photos:

The cable with the electrical tape on it is not normal. It must be terminated inside a junction box if it's still attached to any circuit.

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  • Thank you for that explanation! I did test that power was coming from the associated outlets, but I can't remember if I checked it in every breaker on/off scenario so I will do that later. If the NCV would give weird readings in that scenario then it's possible that's what I was seeing.
    – Homeowner982747273
    Commented Jan 9 at 15:24
  • @Homeowner982747273 One thing you might do is look inside the switch box and check for a red wire. Since you don't have any red wires under the countertop, you might find one coming from the panelboard to the switch. That would be the 2nd circuit.
    – Robert Chapin
    Commented Jan 9 at 16:20
  • I added some pictures above, they are a bit dark so you may not be able to see well, but there is no red wire coming into the switchbox. There are only the 2 black wires, 2 white wires, and 2 ground wires, 1 set each coming from Cables 1 and 2 as labeled in the pictures.
    – Homeowner982747273
    Commented Jan 9 at 16:25
  • That's okay too. It might be somewhere else or you might just have unreliable NCV results.
    – Robert Chapin
    Commented Jan 9 at 17:22
  • Thanks for the update on the cable with the tape! I will put that inside a junction box. I thought it was weird that it was just hanging out there with tape on it.
    – Homeowner982747273
    Commented Jan 9 at 17:39

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