LZW31-SN max current

How much current does the LZW31-SN use itself when operating in neutral mode, not including power consumed by the load? Basically, what’s the peak current being sent down the neutral wire? Is this something you’ve tested or set a spec for with the manufacturer?

The reason I’m asking is that I have AFCI/GFCI breakers in my house, which trip based on (among other things) a difference in current between the hot and neutral wires for a particular circuit. I am installing a LZW31-SN in a box that contains the line and load (but no neutral) for the light I want to control, and also a neutral for a different circuit.

I’m weighing the relative benefits of installing as a non-neutral vs connecting to the existing neutral on a different circuit, vs running an additional wire a couple feet to get to the neutral on the light’s circuit. I don’t need advice about how to wire any of those things, I just have questions about the behavior of the switch itself.

I haven’t seen any documentation that says the max load varies with neutral vs non-neutral.

Edit: It’s not a good idea (I believe against code too in the US) to use hot and neutral on different circuits. Either do non-neutral or run the neutral from the same circuit a few feet.

See chart below for max load by bulb type.

Max Wattage: See below – maximum will vary based on bulb type and whether the heat sink tabs are removed or not

Heat Sink Tabs Not Removed: 400W Incandescent, 300W LED, 150W CFL

One (1) Side Heat Sink Tabs Removed: 300W Incandescent, 200W LED, 150W CFL

Two (2) Sides Heat Sink Tabs Removed: 200W Incandescent, 150W LED, 100W CFL

I should clarify that I’m not asking about the maximum load that the switches can control, I’m wondering about how much power they consume themselves.

When running as non-neutral, controlling 3x 9w LEDs, I measured a current of about 100 mA running through the switch in the “off” position. This was enough to make the lights glow slightly, so I’d probably install a bypass if I was going to keep this configuration, but it surprised me to see that the switch was using about a third as much power when “off” as when on. I knew it would need some current to leak through, but I didn’t appreciate how much.

I did some more looking (at the back side of the wall), and discovered that it was actually easier than I thought to run the extra wire, so that’s what I did (replaced a 2-wire cable with 3-wire, kosher and up to code).

I have one other location that doesn’t have a neutral, where I’m planning on installing a red series dimmer, so I’m still curious to learn more about the disadvantages of a non-neutral setup. I’d like to know more about what to expect before I start opening things up, especially because I know there’s something funky about the wiring at that location, but the details are hidden behind sheetrock.

I guess I’ve got three questions:

  • How much power does the switch itself consume in a non-neutral or neutral setup?
    • I can (and plan to) measure my switch under various conditions, but so far it seems like there’s a big difference between neutral (under 10mA) and non-neutral (over 100mA). I’ll need to get out my more sensitive meter to learn more.
  • What is the most power-intensive operation for the switch? Sending z-wave commands? Flipping the relay? Dimming?
  • In what way does the size/type of the load affect the power consumption when running in non-neutral mode?

This was discussed to some extent in this thread, although not as granular as you are seeking. The Inovelli response was the switch and dimmer draw between .5 and 1W.

I would expect you need a scope to measure the current correctly. 100mA rms current is 12W so obviously that is wrong.

Here are some scope waveforms. The current reached about 100mA peak, but was about 4mA rms.

scroll up to see some black switch measurements.