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Would like some feedback/instruction on converting a three-way to single switch and then install a "smart" switch that requires LINE, LOAD & NEUTRAL.

Current Configuration:

( Switch A ) has (2) black wires and (1) red wire. + ground

BLACK silver screw                RED silver screw
      black screw               BLACK black screw

( Switch B ) has (1) black wire (1) red wire and (1) white wire. + ground

BLACK silver screw
WHITE black screw                RED silver screw

Have REMOVED BOTH SWITCHES and have capped off all of the wires.

With the BREAKER TURNED ON and the SWITCHES REMOVED:
.

( Switch A ) black wire that WAS connected on the bottom right black screw is HOT.

To clarify when the black wire is disconnected from the switch it is HOT.

When this same black wire is connected to the switch it is NOT HOT.

( Switch A ) red wire that was connected on the top right silver screw is HOT.

( Switch A ) black wire that was connected on the top left silver screw is COLD.
.

( Switch B ) black wire is HOT

( Switch B ) white wire is HOT [so this appears not to be neutral]???

( Switch B ) red wire is HOT.

.

The breaker feeds two other lights on different switches. These lights remain on with ( Switch A & Switch B ) removed.

There appears to be a NEUTRAL in both gang boxes.

Thanks for your time.

The first picture is ( Switch A ) [middle switch] is the one that is being replaced / removed. (wires removed)

Switch A

The second picture is where ( Switch B ) was.

Switch B

The first switch, what remains of it, is ( Switch B )

Switch B

This is left side of ( Switch A )

Switch A

This is right side of ( Switch A )

Switch A

Clarification of when wires are hot or not:

When the BLACK wire is disconnected from the right bottom of ( Switch A ) it is HOT.

When this same BLACK wire is connected to the switch it is NOT HOT.

( Switch B ) has been removed and testing wires without connected to it.

When ( Switch A ) is in the ON position ( Switch B ) RED wire hot BLACK wire cold WHITE wire hot

When ( Switch A ) is in the OFF position ( Switch B ) RED wire cold BLACK wire cold WHITE wire hot

Island Light Box Below

Island Light Box

IF cables are coming into the box from the direction of their associated switches then ( Switch B ) would be entering the box, out of view, at the top of photo and ( Switch A ) would be coming in at the back hole, in view.

3 Gang Box For kitchen recessed / kitchen island / mud room light

3 gang for kitchen

The middle one is for the kitchen island light. WHITE wires are nutted together, see behind switch.

  • You are on the right track looking at screw colors, but wire colors don't mean much in 3-way circuits. it's much more important what cables those wires are in, and what the other wires in those cables are doing. . We need to know what else is going on in the box. If able please shoot us pics of the inside of both boxes. – Harper - Reinstate Monica Dec 23 '19 at 4:19
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    Also, is this a stairway? Are you sure the second switch location isn't required by Code? – Harper - Reinstate Monica Dec 23 '19 at 4:19
  • Can you post photos of the insides of the switch boxes involved please? Also, where are these switch boxes located, and what do they control, as multi-location control is mandated by Code for some lighting outlets... – ThreePhaseEel Dec 23 '19 at 4:29
  • Not a stairway. Its an kitchen island light. Get this one switch is in the adjacent family room and the other switch is in the adjacent mudroom. – I Own I Owe Oh My Dec 23 '19 at 4:32
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    The 3 gang may have a neutral in the back I see a bunch of white, if nutted together they would be the neutral. What type or brand of smart switch? – Ed Beal Dec 23 '19 at 14:44
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You don't have the neutral you think you do

This particular light was wired as a spurred three-way switch off of an old-style switch loop, so you actually do not have a neutral at either switch box, despite the white wires being present in both. In your case, we can tell white is the always-hot wire at both switch locations, even, from the fact that it's the white wire nutted to the bundle of black wires in the light box.

From there, we know that the black wire in the cable from the light to switch A is the switched-hot, and that the black and red wires in the cable between switch A and switch B were the travellers in your old setup. Since there's no neutral in all this, and the Insteon 2477D requires a neutral to work (i.e. power the smarts inside), we can't use that part here by itself.

Never fear, though! Insteon to the rescue!

However, since you are working in the wonderfully flexible system that is Insteon, there is a way to get what you want, simply by adding some more parts. You will need an Insteon In-lineLinc™ Dimmer module (model 2475DA1) for this, in addition to the dimmers you already have.

Once you have the correct pieces for this job, you'll need to rewire things as follows, starting with the fixture box:

  • All the fixture-box blacks get nutted to each other and to the in-line dimmer's black (LINE) wire (but not the fixture's black wire! otherwise, the light will simply be on all the time)
  • All the fixture-box whites get nutted to each other, the in-line dimmer's white (NEUTRAL) wire, and the fixture's neutral wire
  • The bare (GROUND) wire from the in-line dimmer gets nutted to the existing bare pigtail from the box and the fixture's bare ground wire
  • The fixture's black wire, finally, gets nutted to the red (LOAD) wire from the in-line dimmer

At this point, we move on to the first switch box, where the dimmer that replaces switch A needs to be wired as a 3-way secondary controller:

  • The two black wires that went to switch A get nutted to each other and to the black (LINE) wire on the first dimmer
  • The two white wires associated with the switch A circuit that are nutted to each other need to have the white (NEUTRAL) wire from the first dimmer nutted in with them
  • The bare ground wire that went to switch A needs to be nutted to the bare (GROUND) wire from the first dimmer
  • The red wire that went to switch A and the red (LOAD) wire on the first dimmer both need to be capped off individually, as neither wire is used in this configuration

Now that we have switch A done, we can button up that switch box and move onto wiring switch B as an Insteon 3-way secondary as well:

  • The black wire that went to switch B gets nutted to the black (LINE) wire on the second dimmer
  • The white wire that went to switch B gets nutted to the white (NEUTRAL) wire on the second dimmer
  • The bare ground wire that went to switch B gets nutted to the bare (GROUND) wire on the second dimmer
  • And, finally, the red wire that went to switch B and the red (LOAD) wire on the second dimmer both need to be capped off individually, as again, neither wire is used in this configuration.

Now, you can button switch B's box up, turn the breaker on, and set to work configuring the Insteon links so that the two wall dimmers are linked to each other (in a 3-way cross-link) and to the in-line dimmer module (so that it can receive commands from both dimmers). Once the Insteon links are configured, you can turn the breaker off again, put the ceiling fixture back up, turn the breaker on, and enjoy your multi-way dimming setup!

| improve this answer | |
  • Really appreciate all of the information. Not exactly what I was wanting to do but will consider it. If it makes a difference there is a non-hot NEUTRAL in the 3 gang. An Insteon dimmer controlling recessed lights is attached to it. Any other option to do this with one switch at the 3 gang and remove the switch at the 2 gang. Should I consider a new run of romex from 3 gang to fixture box. – I Own I Owe Oh My Dec 23 '19 at 21:11
  • @IOwnIOweOhMy that neutral can't be used because it's from the wrong cable (and perhaps even the wrong circuit altogether). One could replace the 14/2 from the 3-gang to the fixture box with a 14/3 and bring neutral down that way, but it'd likely be more expensive to do that than to use the In-LineLinc. (And the Insteon stuff is all capable of 3-way (or more!) control, you just need to use Insteon controllers at all locations, instead of mechanical switches) – ThreePhaseEel Dec 23 '19 at 21:12

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