I replaced a single pole switch with a Lutron Maestro dimmer. However, the line remains "hot" when dimmer turned off. Have verified that the hot wire in box is wired to bottom lug of dimmer. I thought the dimmer was defective so I purchased another but having the same issue! I rewired the original single pole switch and verified that power turned off when flipping switch. I might add that I don't have the light fixture connected to the wires at the ceiling fixture yet, but don't think that this should matter since the original single pole shuts off power here.

  • What kind of light bulbs in the fixture?
    – Tyson
    Commented Apr 12, 2017 at 21:47
  • The pendant fixtures will have G9 Halogen bulbs. Planning to change out with G9 LED though. As I stated, no fixture is connected at the ceiling yet. Wire nuts only for now.
    – Grant
    Commented Apr 12, 2017 at 21:54
  • 1
    Ahhh I missed that sorry, I'd wire in some kind of fixture and retest , likely phantom voltage. Which model maestro? lutron.com/en-US/Products/Pages/StandAloneControls/… you may need the C/L version for an LED load, although I've seen the the standard model work ok with some LED loads, but you can't adjust the dimming range until use the C/L model.
    – Tyson
    Commented Apr 12, 2017 at 22:03
  • Yes, I purchased the C/L model.
    – Grant
    Commented Apr 12, 2017 at 22:54
  • Either retest with a load attached or use a low impedance volt meter such as amazon.com/dp/B003WLLH2Y/ref=cm_sw_r_sms_c_api_W3R7yb74R4HW1
    – Tyson
    Commented Apr 12, 2017 at 23:55

2 Answers 2


Dimmers work differently

To start with, a dimmer is a smart device, and all smart devices need power themselves for their own internal functioning.

How do they get power? That's kind of a problem. A plain switch loop doesn't need neutral - it gets always-hot and delivers switched-hot. So many older switch loops are wired with no neutral. However, old style incandescent bulbs have a unique property: when they are not lit, their resistance is near zero. So many smart devices (and almost all older ones) power themselves by leaking power through the incandescent bulb. CFL and LED bulbs don't play well with this, unless they're designed to.

How do newer smart devices power themselves?

  • Some newer still do it this way, because they're afraid of having a lot of returns from consumers who find out they don't have a neutral.
  • Some simply require a neutral.
  • Some misuse the ground wire as a neutral, and they don't blow GFCIs because they flow very little power. (How they make it through UL listing is a mystery to me.)

Dimmers which require or steal a neutral should not put any power on the line when "off", but you should not count on that for safety!

A dimmer without a neutral should, and must, energize the switched-hot at all times.

Some dimmers have a hard-switched "off" (and sometimes a hard-switched "on")... but it's past a stiff "detent" and people never push the switch hard enough to realize the detent is there.

  • I've replaced single pole switches with this model dimmer switch for a couple of recessed LED lights in this house. The only difference with the issue that I'm having now is the fact that there is no light fixture wired up to this switch loop.
    – Grant
    Commented Apr 13, 2017 at 1:12
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    @Grant, your observation is exactly what you should expect with the smart devices powered by leaking current as Harper described. Tyson's comment about low-impedance voltage testers/meters is worth paying attention to. Commented Apr 13, 2017 at 8:28
  • 1
    I'm not sure a lower impedance tester will make enough difference. The bottom line is the (intended) leakage is trying to lift/float the switched-hot to 120V -- and in this case there is absolutely nothing to sink it to neutral, so it stays at 120V. It also means the "powered by leakage" switch will not power up since there is no possible path for leakage. All this is to be expected. Commented Apr 13, 2017 at 16:01
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    OK, thanks! Sounds like I should be good to go once I install the 3 pendant lights on this circuit. I suspected that this was the case but just needed clarification as I was thrown offtrack a bit because the original single pole switch for incandescent had no voltage leakage.
    – Grant
    Commented Apr 14, 2017 at 6:01
  • First off , Harper this is a really informative answer. From what you stated i think the one scenario applies to something I’m facing. A Eaton dimmer switch with one 14/2 time coming in the switch box so white wire acting as common/always carrying current entering box and the black leaving the box as hot with switch on and no current when switch is off. For some reason the dimmer switch (which is new) shows 120v when on and 15v when off then it can be attributed to the dimmer leaking current as intended when I’m off position. When you say smart switch what do you do you mean?
    – Qiuzman
    Commented Feb 7, 2023 at 22:07

Lutron 3-way switch failure AND SOLUTION

I have an LED lighting system on a 3-way with a dimmer. The LEDS would never fully turnoff. A real head scratcher.

My multimeter showed voltages all over the place. 90, 70, 20. Blew my mind.

Of course, I thought it was the dimmer. WRONG!

It was the Standard Lutron 3-way. I tore it apart to figure out how it could possibly fail so strange. My conclusion?

Lutron heavily greased the internal contacts. Open or closed, this grease bridges the contacts. Over time and use, small particles of metal from the contacts get entrained in this grease, causing it to become slightly conductive, and you get a high resistance short.

That means YOU CAN NEVER FULLY TURN THE SWITCH OFF, and it is constantly drawing power.


  • 2
    You do not understand the electronics of the switch. Any electronic switch that does not have a neutral has to draw a small amount of current through the circuit to work. Your conclusion is way off base, -
    – Ed Beal
    Commented Jan 14, 2019 at 15:18

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