Currently under sink I have a 12/3 and a 12/2 wire that come into a junction box. The 12/2 comes from another wall GFI and the 12/3 comes from the breaker panel. How can I connect wires in box to add the necessary GFI outlet on the island along with an undersink outlet and switch for the plug in disposer and run the direct wire to the hard wire D/W.

1 Answer 1


The wiring should look something like this...

enter image description here
Grounding conductors not shown

Depending on where you live, the disposer receptacle may or may not have to be GFCI protected. The drawing shows GFCI protection, but it may not be required.

Also, if the line coming to the other receptacle is already GFCI protected, you don't need a GFCI receptacle there either.

  • Except he said the 12/2 comes from another wall GFI (outlet presumably) so the receptacle on your left doesn't need to be GFCI (as long as it's fed from the LOAD side). Your handling of the complex MWBC+GFCI situation is right on the money. Dec 20, 2016 at 21:19
  • Thanks, @Harper. I mentioned in the post that the GFCI receptacles may not be required. Just keep in mind, simply because a line comes from where a GFCI is installed, does not mean the line is GFCI protected.
    – Tester101
    Dec 21, 2016 at 11:39

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