Wiring – Installing a smart dimmer switch into 3 gang box

dimmer-switchinstallationwiring

I have installed dimmers in a single box and a gang box with 2 switches but never a box with 3 switches. And there's some confusion, so hopefully someone can help. I am installing a new smart dimmer switch as shown in my photo. I am replacing the middle switch. The new dimmer requires neutral, and those are all tied together in the back of the box.

  1. I plan to connect the neutral from the new switch to the neutrals in the back of the box.
  2. The switch being replaced has two hot lines connected to it as you can see in my photo. Since I only need one hot wire to the new switch, what should I do with the 2nd hot wire that I remove from the switch I am replacing?
  3. My problem is with the red load wire on the new switch. Do I remove the load wire from the leftmost switch and connect it to load on the new switch? Or do I have to actually connect a separate load line to my new switch red/load wire?

Just a note: The rightmost switch is a 3-way and is independent of this install and is not connected in any way to the lights which will be connected to the dimmer.

Any help would be appreciated. I'd rather ask before trying this. Clearly, I am not an electrician! If I were, then you definitely wouldn't want to hire me!! :).

NOTE: Had an error in first photo. The one showing is now correct.

Current config

Best Answer

I think the kind of tester you are using is not accurate enough.

Here's a good way to find out which wire is HOT and which is LOAD on the middle switch:

  • turn off the circuit breaker
  • Turn off the left switch
  • Disconnect both wires from the middle switch and cap each one with a wire nut
  • Turn on the circuit breaker
  • Carefully remove the wire nut from one of the disconnected wires and touch it to the hot terminal on the left switch - if the living room recessed lights come on, that was the LOAD wire - mark it with a bit of tape
  • If the living room recessed lights do not come on, touch the wire to the load terminal on the left switch - if the eyeball light comes on then that was the HOT wire
  • Replace the protective wire nut before continuing
  • If no lights come on, try carefully repeating the test with the other disconnected wire
  • remember to turn off the circuit breaker again before continuing

These tests depend on your switches being wired correctly in the first place. If both wires from the center switch behave exactly alike, or if your testing trips the circuit breaker, your wiring may have errors that will require much more analysis.

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