LZW30: Seems to be leaking about 30VAC when off

I have a new LZW30 On/Off switch installed to switch the outlets with only floor lamps plugged in, replacing a dump on/off toggle switch (no 3-way here) – the LZW30 has neutral wired.

Sort of works, except that when the LZW30 is off, it’s leaking about 30VAC, enough that an outlet tester is flickering when plugged in (and the switch is off). Checked the wiring and it seems correct.

Only twist is that the outlets are wired with 14/3 and the top/bottoms “separated” (tab broken out); so the lower outlet is always on and the upper is switched for the lamps. The power from the panel goes into the Line and the always-on circuit (black wire in 14/3) is obviously tied to this. The red wire in the 14/3 is connected to the Load for the switch.

Any thoughts?

Phantom voltage?

I don’t believe it happened with the old toggle switch. I’ll take out the LZW30 and put back the toggle and check it again.

Where would you expect the phantom voltage to be coming from? (I was kinda guessing that the switch is leaking voltage, but maybe it’s coming from elsewhere).


Phantom voltage typically comes from conductors being in close contact with each other. You see it a fair amount in 3-way circuits because the “dead” traveler runs next to the energized traveler. You have a similar situation where you have a 3-wire to a split receptacle where the constantly hot conductor runs along side of the switched conductor. When the switched conductor is off, you might still see phantom voltage on it.

That’s not to say that the switch couldn’t be leaking it as well. I don’t know enough about this to comment.

Most references on phantom voltage consider it benign.

If you pull the air-gap on the LZW30 do you see the same voltage?

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To follow up on this, I did some investigating and it’s just induced current in the 14/3 wire. If I remove the red wire from the Load terminal, I still read the ~30VAC on that outlet. If I shut off the power to the black wire, then it drops to zero. So it’s definitely not the switch and there’s nothing else plugged into that circuit.

There’s a nice explanation here:

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