Electrical mystery - could use some help to solve

[Skyman]

Reaching out to the local sparkies here for help solving a mystery that, so far this morning, has me stumped.

Scenario: Jack & Jill bathroom. Pair of three-way switches, and a pair of recessed ceiling fixtures that are presently housing LED lamps. Either switch can be toggled to energize or de-energize the lamps in a (mostly) normal way.

What's going on: When lamps are off, they still glow faintly.

Investigation thus far has revealed the presence of around 12.5 VAC across the terminals in the lamp sockets with the circuit open.

Further investigation has revealed that with the red wires disconnected from both switches, there is around 14.5 VAC present between either of these red wires and ground. The faint glow of the lamps is not present when the red wires are disconnected from the switches. Removing both lamps from the fixtures does not eliminate this phantom 14.5 VAC at the red wires.

Switches ohm out normally when fully disconnected. Infinite resistance present across terminals when open.

There is also an exhaust fan that is controlled by a set of three-way switches, and all of that behaves normally. I see no similar, phantom voltage at any of the terminals of either of those two switches.

I am doing some serious head-scratching trying to figure this one out. Any advice from the GJ brain trust would be heartily welcomed.





Switch on left is lights, right is fan. Ignore the blue tape. I used it to remind me which black wire was where while I had things disconnected:





Switch on right is lights, left is fan. Ignore the blue tape here also:




I see no meaningful relevance, but these are the lamps:



Many thanks in advance.

 

[wyliesdiesels]

What meter are you using when you get this 14.5v reading? Could be phantom or induced voltage that will go away when there is a load on the wire

The red wires are the traveler wire between the switches so there shouldnt be any voltage on it when disconnected at both ends

 

[rlitman]

Are one of the switched lit? The little neon bulb in a lit switch will pass some current through an incandescent bulb's filament to light itself without a neutral, but when only LED bulbs are in the circuit, the LED bulb may make use of that minimum amount of current to glow.

If that's all it is, then it shouldn't be an issue with a dimmable light unless the glow bothers you. Does it act like a night light that's useful? I actually have a hard wired night light in my bathroom.

 

[rmanrman]

Sounds like phantom voltage. How long of a run from switches to electrical panel ?
Try a different led bulb manufacturer
Not great value Walmart bulbs.

 

[u2slow]

Pretty common with 3way switching. LED is just more sensitive to the trace voltage. A volt tick-tester with often light up on all the switch wires for the same reason.

If other attempts fail, may want to consider a wireless smart-switch pair.

 

[sparky 1971]

Are one of the switched lit? The little neon bulb in a lit switch will pass some current through an incandescent bulb's filament to light itself without a neutral, but when only LED bulbs are in the circuit, the LED bulb may make use of that minimum amount of current to glow.

If that's all it is, then it shouldn't be an issue with a dimmable light unless the glow bothers you. Does it act like a night light that's useful? I actually have a hard wired night light in my bathroom.

^^^this^^^

 

[Skyman]

What meter are you using when you get this 14.5v reading? Could be phantom or induced voltage that will go away when there is a load on the wire

The red wires are the traveler wire between the switches so there shouldnt be any voltage on it when disconnected at both ends

Thanks for the reply.

That there's some voltage present when the red wires are disconnected at both switches, leads me to think that this circuitry isn't wired with a single, point-to-point red wire as the traveler between the switches. Disconnecting the red wires kills the faint glow of the lamps, which also seems to confirm the presence of the low-level voltage.

I'm using a decent DMM that I trust. I did just repeat the measurements with another identical meter, and it's showing closer to 5 VAC, which also puzzles me a little. Could be the battery in one or both of them is going a bit soft, or more likely there's a difference in how much load each meter places across its leads, but something's definitely there.

 

[Ducky]

I had a similar issue a few years ago when I was upgrading the overhead lights and receptacles in 2 of the bedrooms. I was replacing the light fixtures with some LED fixtures from Costco. I had done the lights in both rooms and some of the receptacles in the first bedroom. That night I was up in the wee hours and noticed as I walked by the second bedroom that the new light was glowing slightly. I checked the other room with the same type new light and it did not glow. Both worked normal otherwise. The next day I continued with the receptacles replacements. When I got to the last receptacle in the second bedroom, I noticed that the hot and neutral wires were reversed. There was also some wires connected that continued on from the receptacle. I removed the wires that continued on and flipped the circuit breaker on. The overhead light was now dead. I replaced the receptacle while correcting the wiring and reconnected the wire from the light. Everything worked and the light no longer glowed when off.

 

[Ducky]

I forgot to mention that this was the original outlet and was wired incorrectly almost 50 years ago. I guess incandescent lights don't care.

 

[Skyman]

^^^this^^^

Thanks for the replies, guys. These are not illuminated switches, but there are other switches elsewhere in the house that are illuminated with neon bulbs. It sounds as though this is probably what's causing this phenomenon.

The LEDs aren't glowing enough to provide night-light illumination, but I do keep a plug-in LED night light in the same room (removing it doesn't alter the behavior of the lights in the ceiling).

I don't need to know this, but am curious as to whether there's another accepted way to wire this room, other than having the red wire as the traveler going nowhere but point-to-point on the two switches. I suppose it's possible that the small voltage I'm seeing on this red wire when there's no red wire connected to either switch could be simply induced by its proximity adjacent to other wires.

 

[Skyman]

Sounds like phantom voltage. How long of a run from switches to electrical panel ?
Try a different led bulb manufacturer
Not great value Walmart bulbs.

It's a pretty long run from the panel to this top-floor bathroom. I'd guess at least 70 feet, possibly quite a bit more.

I should note that the faint glow itself doesn't bother me at all. It just seemed to me that it might be suggestive of a fault that should be corrected.

 

[walta]

Your digital meter reading will not be accurate in a circuit without a load because it has a very high impedance and will literally pull static voltages out of the air and display a value.

If the LEDs glowing bothers you replace both switches and my guess is 80% of the time the glow will stop.

The other 20% of the time the power making the LEDs glow is from capacitive and or inductive coupling between the wires inside the Romex cables.

If you install an incandescent light bulb in one of the sockets the LEDs will stop glowing when off. Because the tiny leakage that is lighting the LEDs will take the path of least resistance thru the incandescent lamp and avoid the LEDs.



Walta

 

[Skyman]

Thanks all for the replies. With y'all's help, I've concluded that it's not suggesting a problem, so it will remain as it is.