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Please help if you can... I just replaced some old 3-way switches with new Maetro+Controller 3 way dimmers. I did this on 2 light separate lights (I.e. changed a total of 4 switches... 2 of these: Lutron MA-R-WH Maestro Companion 120V 8.3A Designer Digital Dimmer Switch and, 2 of these: Lutron Maestro C.L Dimmer Switch for Dimmable LED, Halogen & Incandescent Bulbs, Single-Pole or Multi-Location, MACL-153M-WH

I got the same behavior on both circuits. Here is the problem. When I was done wiring up, the lights looked a little dimmer than before (everything else worked perfectly). So, I measured the voltage at one of the 4 chandelier bulb sockets where I got a voltage to ground of 100VAC!!! Bizzar! There is only one light being controlled on each dimmer circuit (a chandalier with 4 small bulbs...I.e. low load). So, I measured the voltages along the circuit. Here is what I found:

  1. Power leg into first dimmer: 120V

  2. With the light turned on, the voltage on the same dimmer: 100V on one connection and 107V on the other (pretty sure the 107V is the phantom voltage).

    3.The voltage on both powered legs of the 2nd dimmer is 100V--I.e. 100V from the first transformer and 100V on the line to the light fixture (107V also on the secondary connection/fantom?).

As mentioned above, I have a second light that I also changed the switches on. Same power coming in and same neutrals. I got the same result. I disconnected the second one to see if it was impacting the first... it didn't seem to be).

Thoughts?

Thank you in advance. Dave

Circuit schematic

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  • Hello, and welcome to Home Improvement. How are you measuring these voltages? Note that generic voltmeters have a tough time with strange power waveforms such as dimmers put out. And, you should probably take our tour so you'll know how best to participate here.
    – Daniel Griscom
    Feb 16, 2020 at 18:51
  • 1
    Why is this a concern for you? Is the loss of dimming range on the high-end causing you an issue?
    – ThreePhaseEel
    Feb 16, 2020 at 19:09
  • Dimmer Companion
    – Harper - Reinstate Monica
    Feb 16, 2020 at 19:58
  • Noting that these are series-wired dimmers, have you tried replacing one bulb with incandescent? Does that help?
    – Harper - Reinstate Monica
    Feb 16, 2020 at 20:12
  • How are you measuring this voltage exactly? Measuring dimmer output can be weird, because the output is not sine waves.
    – Harper - Reinstate Monica
    Feb 16, 2020 at 20:19

1 Answer 1

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It is KNOWN that you have a voltage drop across a dimmer,..even when turned up/on all the way. They could MFGR them so it is a true bypass when on all the way, but they do not. I assume it is to save a buck or two. The ones that are noticeable.....I usually take them back. I've had a few that were only letting 100 volts get by,...you ALWAYS notice it is dimmer at 100,.. and usually, even at 110. I think the decent ones loose about 5 volts only, and you can live with that. In the sound business, where you are trying to keep all frequencies under control evenly,..people actively seek out a potentiometer that has a true bypass of the internal circuit when it is turned all the way on...and they expect to pay extra (not much,..it's easy to do).,

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    Welcome to Home Improvement. With all the SHOUT CASE and lack of formatting, this feels more like a rant than an answer. Please take a minute to take the tour, then look through tips on how to answer then feel free to edit your answer.
    – FreeMan
    Oct 11, 2022 at 14:01

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