FAQ: Zwave Switches 101 for Noobie (What's an Add-on Switch for and Do You Have to Replace All the Switches in a 3-Way?)

project_lighting

(David Christensen) #1

Brand new to Smartthings and trying to get some areas of the house “connected” ASAP. Most of the devices available are intuitive enough to figure out, but one area that seems to be a bit confusing is the on/off light/scene/etc. switchs that are available. I am mainly confused with the 3/4-way options, the add on switches and how these inter-operate with existing switches (if at all).

My initial understanding is that I can replace a single pole switch with something like the GE Z-Wave Wireless Lighting Control On/Off Switch, if I want it to be able to dim the lights I need one that supporting dimming.

If I have a 3/4 way lighting setup I need to get a zwave/wireless switch that is capable of supporting 3/4 way. However does this mean I can just replace one of the existing switches with on zwave switch? Is this a use case for the add on switches? What use cases do the add on zwave light switches apply to?

I know I am not be covering every use case/light switch possibility so any other 101ish explanation would be welcomed.

Thanks in advance for any help you can provide to get this noob educated in all things Smartthings!

David


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(Rick S) #2

David,

In a 3 or 4 way switch setup, you need 1 Smart Switch and every other switch must be an Add-On switch of the same make model or at least one that is compatible with the Smart Switch


Hope this helps
Rick


#3

Welcome! :sunglasses:

  1. yes, you usually have to replace all the switches in a three-way

If you have a three-way or four-way set up, you will have to replace all of the switches with switches specifically designed to work together. This is because network switches are not wired quite the same way as nonnetworked switches. A network switch has to always have power so that it can hear the next “on” command from the network even though the switch appears to be off.

With non-networked switches, a three-way is often wired in a sort of figure 8 loop so that one switch is completing the circuit and the other switch has been dropped out of the circuit. You can’t do that with the networked switches because of that need to always have power for the radio.

Consequently, you usually have to replace all the switches. And because different models use somewhat different methods to communicate between the switches, you have to replace all the switches with ones specifically designed to work together.

There is occasionally an exception to this rule. One model of the 2017 Zooz switches and some of the Lutron Caseta models can use an existing toggle switch as an auxiliary depending on the specific wiring in the house, but that’s unusual.

  1. What’s an add-on switch?

In a three-way set up with network switches, one switch will be the master. That’s the one that actually controls the load to the light fixture. The other switches will basically just act as remote controls for the master switch. They may be connected to the master switch through physical wires (usually called traveler wires) or they may communicate to it wirelessly. But all they’re doing is telling the master to turn the current on or off to the load.

Different manufacturers call the non-master switch by different names. “Auxiliary,” “add-on,” “dummy,” “slave,” “remote”-- it all means the same thing, a switch which does not directly control the current to the fixture but rather just sends a signal to the master switch.

  1. different brands have different features

For more about the different features that you might find in network switches, see the following thread (this is a clickable link)

In particular, note that some brands, such as Linear/GoControl, include a Z wave radio in their auxiliary switches. These still are not load control switches, but because the auxiliary can talk directly to the hub, it can be used in some situations without a master, such as when you want the dummy switch to control a smart lightbulb. Even so, these auxiliary switches cannot control the current to a light fixture. But they do show up on your things list.

Other brands, such as GE, do not include any radio in the auxiliary switch. Instead, it must be connected by a physical traveler wire to the master switch, and it must be on the same circuit. So these add-on switches are invisible to the SmartThings hub and can’t be used for any other purpose except to communicate with their matching master switch.


Looking for advice on my first project: entryway smart lighting
#4

Hi JD,
Sorry to bump and old post, but didn’t find a newer one that was as appropriate.

Diving a little deeper perhaps:

  1. Am I right in assuming GE & Leviton Addon ZWave switches always require the traveller wire to be 3+ way, while Linear always does NOT?
  2. If those with traveler wires a)don’t have radio transceivers, b) don’t talk to the Hub, how do they communicate back to the Master switch…some proprietary signal down the traveller wire?
  3. Is it safe to assume, in a retrofit scenario (replacing hardwired mechanical 3 way switches), that the existing traveler wire is appropriate to connect to the replacement ZWave Addon switch Traveler terminal? I know there are many 3-way mechanical switch scenarios, depending on where the fixture is, the Line Power, each switch, etc.
  4. In a upgrade of a mechanical 2-way (one switch) to 3-way scenario with ZWave switches, I’ve got to think the Linear switches are much simpler, no traveler wire to route between Master and Addon. Seems like this design is far superior from this standpoint, why don’t all manufacturers do it this way? Is there a down-side, besides $$$?
  5. Since the Linear Addon switch does have a radio and does communicate to the Hub, I would guess that a Linear Addon might create the 3-way function with any brand of switch, no traveler wire required, right? I’ve read that Linear Addon works via Association, something I don’t understand.

Thank you!
David


#5

I’m reluctant to ever say “always.” :wink: You just have to check each model to be sure, but as of this writing, July 2017, in general that is correct.

.2. If those with traveler wires a)don’t have radio transceivers, b) don’t talk to the Hub, how do they communicate back to the Master switch…some proprietary signal down the traveller wire?

Yes. It’s a pulse connection.

.3. Is it safe to assume, in a retrofit scenario (replacing hardwired mechanical 3 way switches), that the existing traveler wire is appropriate to connect to the replacement ZWave Addon switch Traveler terminal? I know there are many 3-way mechanical switch scenarios, depending on where the fixture is, the Line Power, each switch, etc.

It’s never safe to assume anything about electrical wiring. You should always map every segment of every circuit so you know exactly what’s going on. People do some crazy stuff when they don’t really understand how wiring works.

.4. In a upgrade of a mechanical 2-way (one switch) to 3-way scenario with ZWave switches, I’ve got to think the Linear switches are much simpler, no traveler wire to route between Master and Addon. Seems like this design is far superior from this standpoint, why don’t all manufacturers do it this way? Is there a down-side, besides $$$?

Different things work for different people. The primary benefit of the devices that use the physical traveler wires is that they will always work even if your home automation system fails completely. Some people prefer that design. And there is generally a dollar difference, as you mentioned. Certainly the ones that use a “virtual three-way” where there are no physical traveler wires give you more options in where to place the auxiliary, so that’s a benefit for that style.

.5. Since the Linear Addon switch does have a radio and does communicate to the Hub, I would guess that a Linear Addon might create the 3-way function with any brand of switch, no traveler wire required, right? I’ve read that Linear Addon works via Association, something I don’t understand.

There are two completely separate methods here. :sun_with_face: :first_quarter_moon_with_face:

A) because SmartThings is a multiprotocol platform, it is indeed possible to use any two switches which can be controlled by the SmartThings hub to set up a virtual three-way. You can do this using the official smartlighting feature without needing anything else. It won’t matter what brand or model or protocol each switch is – – as long as each communicates with the hub when it is turned on and each can be controlled by the hub, you can set it up so that the hub receives a message from the first switch and then the hub tells the second switch to turn on. And the location of the two devices won’t matter, you could have a switch in your bedroom control a switch on your front porch. As long as both switches can talk to the hub, you’re fine.

B) completely separate from this, and completely independent of SmartThings, the Z wave protocol allows for what is called “direct association.” If the auxiliary is a Z wave device that supports association for Control of another device and the master is a Z wave switch within 1 hop of the auxiliary, then association allows you to set it up so that the auxiliary has permission to talk to the master switch directly without telling the hub what it has done.

The benefit of this is that it tends to be very fast. The drawback is that the hub doesn’t know that the events have happened, so the status in the App will tend to get out of sync with the real devices.

In addition, association only works between 2 zwave devices, only works if the device is specifically designed to be able to use Association for control of another device (and many are not), and only works if the two devices are pretty close together.

There are times when zwave association is useful, especially if you need really quick response, but most of the time if you are using SmartThings the benefits of creating your virtual three-way using the hub as a middleman will outweigh the benefits of direct association.

The following FAQ on GE three-way wiring may also be of interest:


#6

Hi JD,
Thanks for your informed response. Especially on this one, your linked FAQ for GE 3ways switches indicates can’t assume direct replacement of mechanical 3-way switches.

David


(Sam) #7

I have a 3 way switch setup. One switch is at the front of the room and I use it all the time. The other switch is at the back of the room and I use it almost never. If I don’t really care about the 2nd switch the back, do I still have to replace that with an Add-On? Or, can I just replace the first one with a smart switch and leave the 2nd one as a dumb switch in the “on” position?


(SimonS) #8

It’s doable, just have to be careful how you wire the new one.

By one of your switch, main hot/black wire from electrical panel comes in (should be connected to black screw on that switch). 2 wires (travelrs) go to the other switch and then the black screw terminal connects to the light (load).

I would open up both sides, see where is the main feed, where is the load. Then label everything, disconnect everything, use one of the travelers to bring constant “hot” to the smart switch, or if it’s the opposite location - use it to extend the light/load end. Second traveler becomes unused - isolate it. Label everything. Blank the unused switch box.

It is possible that by the light/load side, you already have another hot/main and can use that directly instead of using the travelers. However, it could be different circuit so chose wisely :).


(SimonS) #9

zooZ has Z-wave switches and dimmers that can be used with existing 3-4way. That’s right, you only replace one switch.

This can only work IF you have neutral wire at every switch location. The way it works is using one of the travelers to extend light/load to the smart switch (or extend hot to the light/load location, depends where you install the smart switch), then use the other traveler to connect to basic 3 way or regular switch + neutral. You can not dim from secondary location and there is no option to go full brightness when turned on from secondary location.

I got one to test and I am only not happy with lack of ramp time control, found them a bit slow to turn on/off. It would be useful if it could go optional full power (for the dimmer) when secondary switch is flipped on. The other requirement is minimum load - 15watt for the switch (ZEN21 V2) and 20watt for the dimmer (ZEN22 V2)


(Ari Rodriguez) #10

I bought a 1950’s house… so I ran electricity from an outlet closest to the back yard wall to get lights out to my back yard… which im feeding out a 3 way switch to turn on and off from two rooms.
Do I have to change the outlet where the electricity is feeding from? The outlet is indoors and outdoor with the outdoor having a breaker mechanism to the outlet.

I’m a novice at this… so please forgive my terminology.