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I want to replace a simple single pole light switch with a timer switch, which requires red, black, white, and ground. The existing switch is in a triple box, where all three switches have only blacks connected. It looks like all of the whites coming in terminate in the box with a single wire nut.

A similar question was posted about 7 years ago here, at Is it normal to have a light switch setup using only the hot wire?, except the OP wasn't putting in a timer. He/she just wanted to know if the new switch should "follow the original wiring."

In my case, I can't follow the original wiring, because I need a white. (I refer you to the original post because it has a picture of what my box looks like.

So, with a box like this, can I (and how can I) install a timer switch that needs a white?

Many thanks!

  • Do you have a bundle of white neutrals in your box or not? – Jim Stewart Sep 19 '18 at 18:52
  • Jim, yes I do. Like the picture in the question I linked to. – KJIsaacson Sep 20 '18 at 12:01
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I am assuming that there is a bundle of neutrals (the white wires) in the box. First determine which is the line side (hot) conductor and which is the load (switch leg) conductor on the existing switch. This is important since you are installing a time and the Hot must be on the correct lead. First connect the Ground (bare or green) conductor to the timer. Now you connect the Hot to the correct lead (probably the black) and then the Switch leg to the proper lead (probably the red). All that is left should be the connection of the neutral unscrew the wirenut attached to the bundle of white wires, add a pigtail and attached it to the proper location on the timer.

I am assuming you are using safe practices by never trying to connect or splice wires will the breaker is hot. First identify then kill the circuit then splice and connect.

I am not sure you know what a pigtail is so here is an illustration.

enter image description here

Godd luck and stay safe.

  • RME: I thought I could do that, but I wanted to be sure. And I've done a few minor things around the house and am familiar with pigtails. I appreciate your input! – KJIsaacson Sep 20 '18 at 12:05
  • Very important that you read the rating of your wire nuts. Wire nuts are rated to capacity and size of wires. These are likely 14 ga wires, so count the number of existing and check if the new total is within the mfg guidelines. Be sure you have enough torque on these connections. Loose electrical connections are the #1 cause of house fires; so I'm told. Also note, wire colors are not absolute, except for bare copper is always ground. Black is commonly hot, white neutral, etc, but that is not a requirement, just convention. – brehma Mar 29 at 3:25

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