Electrical – Wiring Leviton Smart 3-way Switch when Load Line Goes to the Fixture


I'm converting my home to use all Leviton smart dimmers (DH6HD-1BZ) and LED lights. All has gone well so far with neutral being accessible from most switches.

However I've come across an old-school 3-way with load going to the fixture not the switch box, please see the following diagram:

enter image description here

Switch box A looks exactly as is shown in the diagram. Switch box B however is a larger box with other switches where neutral is present.

I know I need neutral in switch box A as well, but I've heard there is some possible trickery where I can bring neutral over to box A from box B.

So my questions are two fold:

  1. Is it possible to bring neutral over to box A from box B, perhaps utilizing one of the travellers? Can I just use ground as the neutral for switch A (I know this is faux pas, but should be possible right?)?
  2. If it's possible to get neutral to box A, I don't entirely grok how the dimmer and it's remote switch should be wired in the first place. The wiring diagram provided with the switch (see below) isn't this type of 3-way configuration so I'm kind of stumped here as well.

Thanks for your time!

enter image description here

(where: 1=line/load, 2=neutral, 3=ground, 4=first traveller, 5=second traveller)

Best Answer

No. You cannot poach a neutral from the other switches in Box B. This is a Code violation, potential firestarter, and will trip any AFCI or GFCI breakers in use.

There must be separation between the 3 wires coming into that 3-way and all other wires in the box. Nothing can cross that gap except for safety ground.

Since your circuits apparently do have ground wires, you need to search the market for smart switches which do not require a neutral wire.

Since your 3-way setup is a double "switch loop" (i.e. both 3-ways are on a switch loop with power in the light), then you simply have no option to use a neutral-using smart switch. It cannot be done.

The only possibility is to use a "module" up in the lamp proper, which talks to smart switch(es) in the switch sites. At that point the black & white from lamp to switch could be re-tasked to be always-hot and neutral.