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We have three separate circuits of LED lights in close proximity to each other- one in master bath, one in master bedroom, and one in master closet. All are on dimmers. When any one of these three circuits is switched on the other two turn on at a very, very low level- only visible when dark. This happens anytime one of the three circuits is turned on. Any ideas?

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  • This question is basically a duplicate of this canonical phantom voltage question, but I'm not sure "close as duplicate" is warranted in this case because it's about LED lights glowing. There might be another "glowing LED" question that matches, but I couldn't find a good one.
    – JPhi1618
    Feb 7, 2020 at 17:57
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    I would want to take a close look at how they are wired, the dimmer types, and the LED types. Also, are these screw-in LED replacement bulbs, and if so, does changing one bulb to incandescent cure the problem? That's a diagnostic aid, not a permanent solution! Feb 7, 2020 at 23:47

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As mentioned in my comment, I would say this is caused by phantom voltage or induced voltage. This is a problem that is seem more these days because of an LEDs ability to run on very, very low power levels.

What happens is that the alternating current in one wire that is running parallel and very close to another wire will induce a voltage in the wire that is currently switched off. When all the dimmers are off, there is no current in any of the wires, but when one is switched on and the electricity starts to flow, it causes a voltage to appear on the nearby circuits.

This is not enough to shock you, but it is enough for non-contact voltage detectors to pick up, and it can often be measured with some multimeters. Other lighting technologies need way to much power for this to affect them, but the modern LED can have a small glow with the tiny amount of current.

I also found this question where they were able to use a resistor wired parallel to the switch to stop glowing, but they were having an issue caused by a switch with an indicator lamp and not induced voltage, so I'm not sure if that would help in your situation.

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