In my bathroom I have a dual switch box. The left side controls a light, the right side controls a bathroom fan.

I'm trying to convert the light switch (left side) to a Switch with LED Guide Light.

The right side (fan) I will replace with a simple Decora switch.

The old light switch (left) has a black, red, and copper wire.

The new light switch w/nightlight apparently wants a white/neutral wire, as well. Is this white wire mandatory?

I see there are 2 white wires (one from each initial bundle source from the wall) that are connected together. Should I somehow use one of those?

old switches wiring guide

1 Answer 1


Yes, the white wire is required for the light built into the switch to work. It does not affect the switching of the bathroom light. You will need to create a pigtail (a short piece [6-8"] of wire connected to the two in the box) to join to your switch.

In you picture, the red wire going to the switch is the load, and the black wire is the hot.

  • Thank you. Specifically: add an additional 3rd white wire that will go to my light switch bundled together with the existing 2 white wires? Like this: dropbox.com/s/pnk0jq0w90kabnn/… Is this image correct?
    – philfreo
    Commented Dec 9, 2016 at 0:47
  • 1
    Yes, you've got it. Commented Dec 9, 2016 at 0:49
  • 2
    @philfreo A little extra detail: mechanical switches interrupt the hot wire to turn a device on or off. They do not do anything electrical themselves, so need no neutral. Smart switches are themselves electricity-consuming devices, so they need a return path to complete the circuit. This is why smart switches require neutral.
    – user4302
    Commented Dec 9, 2016 at 6:32

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