LZW-31 SN - How does the relay function?

The Red Series dimmer has a relay built in. There is an option to disable it when using smart bulbs.
My question is - When does it actually change states? What controls it?

Does it click on and off when I set dimming speed to zero? Does it only Open when the light is set to Zero? I’m assuming that a Triac is used for dimming on leading edge of the AC wave, so the relay must be ON if any dimming is used.

I have 8 of these switches and some I want to ensure that there is no chance of dimming with two of them (yes, should have gotten some of the switches not dimmers). I just can’t hear the relay do any audible Click.
I searched around and couldn’t find this specific topic posted.


There is a physical relay in the dimmer, but I believe it is only used in a 3-way setup (to physically switch the power output between the Load and Traveler wire).

When you use the “disable the internal relay” (quotes added solely to drive Eric crazy), what you are actually doing is turning on/off a zwave feature called “Command Class Protection”. The LZW31-SN supports version 2 of Command Class Protection, which means you can control the Local Protection and/or the RF Protection. Pressing the config button 8x toggles the Local Protection state between “Unprotected” and “Protected by Sequence.” If you want to control the RF protection, it would need to be done by your hub.

Here are the values:
Local Protection

Value Text Description
0 Unprotected Device operates normally. Can be set by via zwave or by pressing config x8
1 Protection by Sequence Physical buttons do not control the load, but you can still trigger scenes and control associated devices. Can be set by via zwave or by pressing config x8
2 No Operation Possible Physical buttons are completely ignored (note: you can still do some things, like factory reset). Can only be set via zwave


RF Protection

Value Text Description
0 Unprotected Device operates normally. Can only be set via zwave
1 Protection by Sequence Device will not respond to runtime commands (such as on/off/dim), but will still respond to status update requests. Can only be set via zwave
2 No Operation Possible Device ignores ALL RF commands and requests for status updates. Can only be set via zwave

If Local Protection is set to “Protection by Sequence” and RF Protection is “Unprotected”, the physical buttons will not change the load output, but you can still control the load with your hub.

Different hubs may label these options differently, or may not support them at all (Home Assistant currently does not appear to have support for changing RF protection).

Since all you are really doing is disabling some or all control over the device, you not truly “disabling” the relay. You could set the dimmer to 50% and then “disable the internal relay” and the device will remain at 50%.

Setting the dimming speed to 0 (and you would probably want the ramp rate set to 0, not necessarily the dimming speed) just makes the switch turn on or off nearly instantaneously. It does not truly cut the power the way a physical switch or physical relay would.

Note: these are based my own observations and previous forum posts. If anyone knows anything different from what I posted above, please let me know.


I got a chuckle out of this lol

1 Like

an addition to @jtronicus comments.

In the simplest case, disabling the internal relay leaves the output on 100% of the time. This allows one to use the LZW31_SN to control a Smart Bulb (since the smartbulb needs power 100% of the time).

Yet the smartbulb can be replaced with a not so smart bulb with just a settings change on the dimmer. i.e. no physical wiring change.

@jtronicus I think you are correct that this only functions for 3-way setups. That is the only time I can get it to Click.

I’ll have to research this some more. It appears I might have been giving the wrong information.


I also lol’d