No neutral for add-on switch, will Smart Switch still work?

(Kevin) #1

Working on a 3-way setup and I just noticed there is no neutral bundle where I need to install the add-on.

I know the add-on switch will not work without a neutral, but will the Smart Switch still work? We rarely use the light switch where the add-on will be, so I don’t really care if that switch works right now. But I do need the Smart Switch to work, which does require the add-on for the 3-way.

Just looking for a short term solution at the present, so I don’t need other possible solutions to work around the neutral wire. Just need to know if the above example will work.

(Ray) #2

The add on requires neutral to operate. Depend on your 3 ways. You could bring over a neutral from the other box. Have a look at this great 3 ways examples.


It depends on the specific brand and model. There are a few older zwave models that will work without a neutral, but these are only compatible with incandescent bulbs, not with dumb LED bulbs, so the models were discontinued in favor of the ones that do require a neutral. Cooper does still make one of these, but again, only for use with incandescencts.

You do have two other options.

  1. Most models of Lutron Caseta switches do not require a neutral and there is an official smartthings/Lutron integration now though it does require that you also have the Lutron smartBridge ( One smartbridge for each 40 switches). You can get a starter kit which has one dimmer switch, the smartbridge, and one pico remote which can be used as the auxiliary switch for a three-way.

These are nice switches, and they are what we use at my house. :sunglasses:

  1. The new Aeotec nano dimmer switch is an in wall micro which is supposed to be able to work without a neutral, I’m a little skeptical because normally, with the exception of Lutron who hold a bunch of patents, that would mean it could only work with incandescents in that configuration. But maybe they’ve worked something out.

@TheSmartestHouse is carrying these, so they may know more

Assuming the nano does work, those would be your two best options, although if you pick the nano you’re going to have to figure out what you need for the add on switch to go with it.

Updated to correct I just realized I misunderstood the first post, I thought there was no neutral at the master position. My bad. But if you do have neutral at the master position, you can just use the master as a standalone switch, it doesn’t have to be connected to an add on if that’s what you’re asking.

Then, as @navat604 said, you just need to find a way to get a neutral wire to the auxiliary position so you can get that one working as well.

(Dale C) #4

If you are using Jasco/GE versions you definitely need the neutral along with traveler and ground but just like @Navat604 suggests, you should be able to get the neutral jumpered back to the aux location using the “spare” wire in the romex bundle.

(DavidK) #5

It sounds like there are not enough existing wires to use one as neutral, but there would be enough wires if you use the linear aux switch.

The reason I think that with a wired aux switch there are not extra wires is that even though the Zwave aux does not need a power wire, that circuit still needs to be complete to light the light, either the aux switch is closest to load or line, either way the circuit needs to be complete and cannot repurpose an existing wire.

So a wired aux switch you still need both traveler wires.

For the linear Aux, it controls the load switch wirelessly so one traveler can be re-used.

then one wire is power and the other wire, the traveler wire can be re-purposes as the neutral.


I highly recommend the FAQ posted above. I would guess that since you can wire a smart switch in the first box, you will have no issues getting neutral to the aux switch, there are some unlikely exceptions. As a note to the post above, the Linear Aux switch will buy you very little over a regular Smart Switch Aux. Only the last case in the FAQ benefits from the Linear Aux.

(DavidK) #7


you are not suggesting running new wires? Correct?

You are saying repurposing the wires already in the box?

I will look at diagrams again, but I think that using wired 3 ways there are no wires that are “extra”.

In my house I have 3 sets of 3 ways. In each case one box had neutral and one box did not.

Using the linear aux, there was one extra traveler that I was then able to repurpose as a neutral.


Yes. I’m not suggesting running new wires. As you can see in the FAQ, the three options line-switch-load-switch-1, line-switch-load-switch-2 and line-switch-load-load-switch do not have neutrals in the Add-on box but can be wired to add a neutral. Only having wiring like the last diagram ‘load in the middle’ (Power Into Light) can you use the Linear Add-on but not a regular Add-on. Of course the Linear Add-on would also work where the regular Add-on does.

(DavidK) #9

okay I see, there are many many wiring options.

I had assumed that all the different wiring layouts had to be logically equivalent in order for basic 3 way to work.

I have to think about this, they are logically equivalent on some level as the original 3 way worked, but somehow, some wires are in parallel instead of serial or something, not sure what, that logically allows some of the wires in some cases to be repurposed to be neutrals.


If you have neutral in the main switch box, you can use the 3-wire conduit going to the common terminal to bring the neutral into the second box. If you don’t feel confident about rewiring the switches or have trouble identifying the wires, we recommend consulting a licensed electrician for the installation for safety reasons.

You can also send us images of the wiring you have for each box and we’ll be able to provide you with detailed guidance on which product and wiring diagram to use for this set-up: