I have an old house with 3 bathrooms all on the same circuit. Each has a light with a receptacle above the sink controlled by a wall switch. (See image below.) I want to GFCI protect the entire circuit from the first bathroom switch in the circuit. There is 14/3 wire from that switch box to the light, so the switch feeds the light with the red wire. My question: how do I wire a GFCI/Switch combo to protect everything past it in the circuit, including the light fixture?


  • 2
    You could install a GFCI breaker. That would protect the entire circuit. Otherwise you'll have to connect one of the switch loop wires from the GFCI switch combo, to the load terminal of the GFCI switch combo. You'll also have to connect the neutral for the light, to the neutral load terminal of the GFCI combo.
    – Tester101
    Sep 17, 2014 at 1:44
  • Without more information, it's difficult to provide an accurate answer. Does the switch box only have one cable entering it (the 14/3 cable)? If so, you're not going to be able to protect anything other than the GFCI receptacle itself with the current wiring. Unless you install a GFCI breaker. Could you provide some photos, or at least a simple wiring diagram?
    – Tester101
    Sep 17, 2014 at 11:22
  • I added a diagram of current wiring. It is 14/2 from the panel to the old switch and 14/3 to the box where the light is with the red feeding the light bulb and the black feeding the circuit to the other 2 bathrooms. My question is how to replace old switch with GFCI Switch/Plug using the existing circuit. s1372.photobucket.com/user/bob2354048/media/…
    – bob235
    Sep 17, 2014 at 16:34
  • I forgot to say that each of the light fixtures over the sinks have an outlet. My goal is is to protect those electrical outlets.
    – bob235
    Sep 17, 2014 at 16:53

1 Answer 1


Based on the description you've provided in your comment. You should be able to install a combination GFCI switch device in the first bathroom (electrically closest to the breaker box), which will provide GFCI protection to the light and the rest of the circuit. Install the GFCI switch combo as follows:

enter image description here
All grounding conductors left off for simplicity. Make sure all devices are properly grounded.

  • Connect the grounded "neutral" (white) conductor from the feeding cable, to the silver LINE terminal of the GFCI.
  • Connect the ungrounded "hot" (black) conductor from the feeding cable, to the brass LINE terminal of the GFCI.
  • Connect the grounded "neutral" (white) conductor from the cable going to the light, to the silver LOAD terminal of the GFCI.
  • Connect the switched (red) conductor from the cable going to the light, to one of the switch wires of the GFCI using a twist-on wire connector.
  • Using a twist-on wire connector, connect the other switch lead from the GFCI to the ungrounded "hot" (black) conductor from the cable leading to the light, and a short bit of black wire.
  • Connect the other end of the short bit of black wire (from the previous step), to the brass LOAD terminal on the GFCI.
  • Appropriately connect all grounding conductors.

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