Automated 3-way Switches: What should my wiring look like? (US Version)

So you want an automated hardwired light switch, but you’re not sure where to start, and you need 2 switches to control the same light. Well you’re in the right place for a 3-way. The most common wiring requirements of any hardwired automated 3-way light switch is a neutral wire and a traveler. Yes, there are a few…(read very, very, very few) switches that don’t require a neutral, but those will limit you to incandescent only. For those of us using LED, Fluorescent or some other energy efficient bulbs under 20w a neutral is REQUIRED!
So what does this look like?

This is a diagram of a 3-way switch with the neutral run directly to the light. This is not good for automated hardwired light switchs and i would HIGHLY recommend that if you want to automate the light, contact an electrician and have them pull a neutral for you. It’s not as expensive as you think and will save you lots of frustration.

This is a diagram of a 3-way switch with a neutral. The black “hot” connection is broken to turn the light on/off, the white “neutral” connection completes the circuit and the red “traveler” connected the 2 switches allowing either switch to control the on/off state. The bare (hopefully) solid copper wire is the ground. It protects from static build up and from electrical insulation failure, in short it’s only job is to make your home safer. If this is what you see when you remove your wall plate you are a go for hardwired automated light switchs. YAY!


This is a diagram of what you’re automated hardwired 3-way light switch setup should generally look like when you are done. It is very important to know which of your old switches are handling Primary or Auxiliary function and the function of each wire. Getting this wrong can cause the automated switch not to work and can even trip a circuit breaker. Follow your brands wiring diagram completely. Different manufactures handle 3-ways differently. Also Yes there will be some slight differences on weather or not to pigtail (a short wire that leads from the switch to the yellow caps) the load and/or line but your ground and neutral should ALWAYS be pigtailed.
Ultimately, if any of this makes you feel uncomfortable or the wiring diagrams makes your eyes cross… CALL YOUR LOCAL ELECTRICIAN! They are there to help! Bad wiring causes fires and other glitchy weirdness you don’t want in your home. If connecting 9 wires excites your happy place, the term “pigtail” makes you giggle and electrical tape is your friend then… Let’s Get Wired Up!
I hope this help those on the fence… enjoy!

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There are at least 8 different ways to wire a three way, and at least 3 of those work for zwave switches, so there’s no one right method.

GE’s 45609 manual shows two different ways: the one you diagrammed above and another where the hot bypasses the auxiliary switch altogether, but the neutral is connected to both:

One increasingly popular method worth mentioning does not use a traveler wire, but instead uses only RF communication from the aux, either by association with the master or to the hub. This allows the aux to be placed anywhere, or even to be battery-powered as with one of Cooper’s models.

So there’s just a lot more variation than when wiring a single switch.

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Excellent point, i reworded a few things to make it more correct. THX!

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Three ways are always confusing! I find that many people instinctively want to make the master the first in the circuit (closest to the circuit box), but in fact as both your diagram and the GE diagrams show, it often (although not always) makes sense to have the master last on the circuit (closest to the light).

Two more thoughts: wire color is never guaranteed, electricians all too often grab whatever color is to hand. They may then tape or tag a wire with the other color, but there’s no guarantee that will be done at the end that you’re looking at. On the other hand, the screws on the switch are usually color-coded by the manufacturer, so those are a little more likely to be reliable. In any case, you want to pay attention to both the wires and the screws.

For this reason, I highly recommend taking photos of the existing wiring before you detach anything, including showing the screws where the wires attached.

Everybody thinks, “I have a very good memory, I know how it was” but the mind will tend to try to fit things into orderly patterns and often misses in cases like these.

The same reason English speakers can read the following without difficulty:

“Th qick broen fox jumpedd over the lazy dog.”

Is the reason it’s so hard to remember wiring exactly 10 minutes later. Our brains make patterns even where they don’t exist.

If you close this post and half an hour later someone asks you to write down the quotation, you’ll likely write “the quick brown fox jumped over the lazy dog” very easily, and then have a hard time remembering exactly what was different! (One of my engineering professors used to do this in class. Hardly anybody got the phrase exactly.)

So photograph everything, you’ll save yourself a lot of grief. :wink:

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The Z-Wave Auxiliary doesn’t require a Neutral connection??

Most of them do need neutral and pretty much all new one do now. Just need that one extra line on the drawing above.

Yup… It’s a shame there’s no way around that! Old house is very unlikely to have neutral wire at the switch and with old “trickle current” through incandescent bulbs, smart switches used to work around the issue. No such luck with CFL and LCD.

As JD mentioned, different models have different wiring requirements. There is no singular right way other than following the instructions that came with the switches that were purchased. All images provided are examples and it’s possible that none of the examples will match up with the before or after product.

Copying this from the single switch FAQ topic, because it applies here, too.

In the US, code for electrical devices requires that you follow the manufacturer’s directions.

The first rule for light switches and receptacles is that you never try to wire around the switch.

While it is tempting to think only in terms of “this switch turns on that light,” in fact all of the wiring is connected. You have to think in terms of the whole circulatory system. This is why wiring can get so complex.

If the manufacturer says the switch needs four wires (hot, load, neutral, and ground), then it needs 4 wires to operate safely. Don’t try to trick the switch by wiring two screws to each other (bootleg ground) or bypassing the switch altogether for some of the wires. It won’t be to code, but more importantly, you may burn out your new switch–or burn down your house.

Take pictures of the existing wiring before you disconnect everything. That includes pictures of the exact screws the wires connect to.

If you don’t understand what every leg of every connection is for, stop. Bring in an electrician.

Trial and error may be Ok when you’re building a potato battery for your 4th grade science class. It’s a very bad idea for house wiring. :fire_engine: :ambulance:

Do you need both switches to be z wave switches or can the master switch be z wave enabled and the add auxilary be a regular non z wave 3 way switch?

You can’t mix smart switches and dumb switches in a 3-way. The second switch needs to be an add-on switch that is compatible with the master. In most cases, but not all, the add-on is a simple remote that tells the master what to do over the traveler. It has no radio.

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In order to have full functionality, the master and all addons/aux switches will need to be compatible, otherwise the master switch will not always know that state of the circuit.

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Could you bypass the need for smart switches by installing a single relay module to the master switch wiring? Or would the same rules apply as to swapping out the switches themselves? Something like this: https://www.amazon.com/gp/product/B00IRI1CEK

It’s a little more complicated. There are different answers for different situations, and for different models of the in wall micros.

  1. automating just one switch, not a three-way set up. For this, an in wall micro will work fine, and you can put it either at the switchbox or at the light fixture. You can retain the old light switch, but it might not work quite the way you expect. Most people would swap out the light switch for a momentary switch. But that’s up to you.

Two) With some micro models, but not all, you can automate a three-way or four-way set up if you put just one micro at the fixture and run physical wires to the existing dumb switches. Only some micros are able to accept input from more than one wire, though. And you do have the same issue as you have in one) in that the toggle wall switches don’t work quite the way people are used to. But this is a good choice for many situations.

  1. you can automate a three-way or four-way set up by putting a micro at each switch and having them communicate wirelessly, but the wiring on these can get really tricky. For this situation you want to have only one of the switches actually connected to the light fixture controlling that load. For the others you’re only going to use the radio. But as I said, you can pretty much end up having to rewire the entire room to make this work so that every radio always has power. Plus the micros aren’t cheap.

For this third option, it’s typically both cheaper and easier to use one micro or one master switch to control the current to the fixture and then at the auxiliary positions use a Z wave auxiliary switch which is designed to not be loadbearing. Probably the most popular in the US for this purpose is the Linear/GoControl WT00Z1. The switch works just the way people expect the switch to work, the cost is usually just under $30, the wiring is super simple because it’s designed to be not load controlling. When the switch is toggled, it sends a message to the hub which then sends the message to whatever master device you’re trying to control.

http://www.homedepot.com/p/GoControl-Z-Wave-3-Way-Dimmer-Switch-WT00Z-1/206591000

So there are definitely options, it just depends on exactly what you’re trying to do

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Best thing is to start your own topic under devices, as answering this would require some detailed questions and answers which would hijack the FAQ topic. :sunglasses:

https://community.smartthings.com/c/devices-integrations/connected-things

As general advice, if you don’t know anything about electrical work, and you happen to live close to a Home Depot, many offer a free class in installing a switch which can be very helpful. Although it will not cover networked switches, you’ll learn how to use the appropriate tools to map the circuits.

Also, since the GE switches are sold at many Home Depot’s, the instructor will often be able to get you answers to some of the questions about those.

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I’m trying to find a solution to connect a three way switch that operates three different hallway lights. I’d like to use smart light bulbs but have GX23 fixtures. I can’t find any ivory zwave toggle switches to match what’s already in my home so I thought I could use a micro switch.

I’m just not sure which one do use or how to wire it up.

I sent a message to the Smartest Home and this was their response:

“Unfortunately, 3-way switches can’t be wired with Z-Wave like regular switches can — if you have 2 wall switches controlling one light, you’ll need to install the Z-Wave module in the box that has load, line, and neutral wires. Very often, you’ll have line in one box and load in the other, so you can’t wire the Vision module (or any other Z-Wave module we know of) in that type of setting. It can damage the module right away or over time.”

Is there a way to tell the load from the line? I know the load wire is the hot one but how can I tell with the circuit breaker off?

Start a new thread. Take pictures of the switches with the wiring still attach to the switch terminals. Note the number of wires and romex from each switch box and most likely someone will be able to help you.
As on how to measure line and load. Look at the common terminals of the switch. Usually black color. Measure the voltage between neutral and the common terminal. The common terminal with the voltage when the light is On and no voltage with light off is your load. The common terminal with voltage and doesn’t go to 0V while flipping your switch is your line hot.
If you are not comfortable doing this first step then I would recommend taking some basic class at your local hardware depot. It’s usually free and boost your confident as well.

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