In my house I have what seems to be a plain two wire + ground flip switch for the garbage disposal. I need to replace the switch because we added backsplash tiling and want to better match the color. I removed the switch and found that it had 3 black wires going to it plus a ground wire. Isn't this a 3 way switch? This is a hardwired garbage disposal. This switch is NOT part of a box with a plug as well, although there is a GFCI plug about a foot down the wall from it.

The garbage disposal is on the same breaker box circuit as the dishwasher, but the dishwasher has its own disposal in it and I've never heard it turn on the sink disposal. So why would a 3 way switch be needed?


Update: Sideways photo of switch above. (Just turn your head ;-). I noticed that the front of the switch has on/off written on the switch, which would be strange for a 3 way switch to have. So now I'm even more confused.

Front of switch Back of switch Switch as wired Switch box wiring

  • Photo please. It may just be a normal switch controlling two circuits, though I can't imagine why the disposal would share a switch with anything. This sounds like some half-informed homeowner kluge.
    – keshlam
    Aug 1 '15 at 4:56
  • @keshlam Ok, added photo.
    – deltaray
    Aug 1 '15 at 14:47
  • Can you read the manufacturer and model number on the switch? That would confirm the type of switch, if not why it's wired that way. Also, are there any neutral wires in the junction box; could you post a photo of that too, please?
    – Niall C.
    Aug 1 '15 at 15:59
  • Added more pictures. I couldn't find a model number on the switch itself.
    – deltaray
    Aug 1 '15 at 17:49

What you have there is a single pole switch that has been tapped to continue the permanent hot to another source. Perhaps an outlet or dishwasher. If you are installing a new dishwasher it will probably have significantly more amps. This could become an issue with the old practice of putting the disposal and dishwasher on the same circuit.

  • The picture looks like three separate terminals on the switch. Were there versions with a hot tap built in?
    – bib
    Aug 1 '15 at 17:00
  • 1
    @bib the green screw is ground. The two black screws are for the switched circuit. The "back stab" connections on the back of the switch are connected to the screw terminals. Using the screw terminal and the backstab connector avoids the use of a separate pigtail to join the two wires together.
    – TomG
    Aug 1 '15 at 18:58
  • +1 @TomG Of course! I didn't see the backstab in the first picture. Makes total sense. (I've always hated backstabs, so it didn't even occur to me.)
    – bib
    Aug 1 '15 at 20:06

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