48 volts with switch off!

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I replaced some existing incandescent bulbs by LED bulbs, then noticed that they do not switch off completely but still glow dimly.
Checking the voltage at the lamp socket with a high-resistance electronic multimeter, I get a reading of 48v!! A few volts might be OK -- induction, stray voltages, etc., but 48V!!!
This occurs in two different rooms, but I think the various lighting circuits are all connected to one breaker.
What could cause this?
Perce
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wrote:

its the meter, take a walk around high sensitivity meters will show 60 volts under the neighborhood power line........
connect a 100 watt light bulb with the meter voltage will go away.
relax yours must be one of the most frequent questions asked.
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On Apr 5, 3:39 pm, snipped-for-privacy@invalid.com wrote:

I agree, sounds like a bad ground (neutral)
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Which one? The neutral wire is white, the ground is bare. One or the other, please.
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On 04/05/09 04:43 pm bob haller wrote:

OK, but
(1) there are no overhead power lines within a mile. Walking around the house with that meter and a lead trailing like an antenna I see not even a 1 volt reading.
(2) It's a pain that the LED lights don't switch off completely. The voltage with the switch off is sufficient to keep them glowing dimly. Perhaps replacing one of the bulbs by a low-wattage incandescent would hold the voltage down, but that offsets the power saving benefit of the LEDs.
Perce
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On Mon, 06 Apr 2009 17:05:08 -0400, "Percival P. Cassidy"

Cover the bulb - make it completely dark - the voltage will likely go away. You are LIKELY getting a DC voltage FROM the light because an LED is ALSO a photocell. An LED will produce a DC voltage when exposed to light. Green ones are Gallium Phosphide and make 1.65 to 1.74 volts each. Not sure what the white ones are and what voltage they produce but I think they are Indium Gallium Nitride - so likely around the same output.
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On 04/06/09 10:43 pm snipped-for-privacy@snyder.on.ca wrote:

It's only because I walked into a supposedly dark room that I discovered that the LEDs were not totally dark.
There was no ambient light that could have caused any photovoltaic effect.
Perce
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On Mon, 06 Apr 2009 22:43:57 -0400, snipped-for-privacy@snyder.on.ca wrote:

And remember - White LEDs also have a phosphorescent material in them that makes white light from blue - the Phospor actually produces a yellow light.
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On Sun, 05 Apr 2009 16:20:03 -0400, "Percival P. Cassidy"

LED? You don't mean complact fluorescent? I havent' seen LEDs that fit wthout changes.
But in the kitchen with a timer in place of the wall switch, I couldn't get my CFL to turn off. Do you have a timer in the circuit.

A timer in each room, and on lamps, seems unlikely.

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mm wrote:

I'm going to guess here that you have some kind of electronic switch, i.e. a dimmer or something similar. As long as there is enough voltage to turn on the LEDs, a small leakage current from an electronic switch could make them glow dimly.
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wrote:

Yes, a timer, an electronic on/off timer.

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wrote:

That's it. I bet your timer was designed to not require a neutral. As such, it has to draw a little current through the lamps to power itself even when off. x-10 switches are notorious for that, but any electronic device that gets wired in place of a switch and does not require a neutral connection will do it. Usually placing a small incondescent bulb (like a 7 watt night light bulb) or a resister in parallel with the LED's will solve the issue. Or, get a different timer that requires a neutral (if the box in question has a neutral wire in it, Or, get rid of the timer if you don't really need it.
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On Apr 6, 5:38 am, snipped-for-privacy@neo.rr.com wrote:

Yes, agree that the electronic timer is what's causing the bulbs to light dimly. Most of those type devices are designed to work without a neutral, so they rely on some very small current always flowing. In the case of incandescent bulbs, it's not a problem. But CFLs, LEDs take so little current, it's enought o start to light them. If you look at the data sheet for that electronic timer/switch it most likely says it's for incandescent use only.
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On 04/06/09 05:38 am snipped-for-privacy@neo.rr.com wrote:

No timer or dimmer. A regular wall switch.
Perce
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On 04/05/09 10:32 pm mm wrote:

No timer or dimmer. A regular on/off wall switch.
Perce
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On 04/05/09 10:27 pm Art Todesco wrote:

No. Regular "mechanical" wall switch.
Perce
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Percival P. Cassidy wrote:

Possibly a lighted mechanical wall switch?
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On 04/06/09 08:21 pm Art Todesco wrote:

No light in the switch.
Perce
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Percival P. Cassidy wrote:

O well, I just thought of that. BTW, did you try disconnecting the lamp? Maybe the phosphors are still glowing a little .... I know, that's a big stretch!
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On 04/06/09 11:03 pm I wrote:

I hadn't measured the voltage in the second room, but I assumed that the glowing LEDs after switching off had the same cause. In fact this was simply a brief "decay time," probably as a capacitor discharged.

It turns out that it was a lighted switch after all -- but no light had been visible in the switch with the CFL bulbs that I replaced by LED. And even when I had the switch hanging out of the wall. the "Lighted" label was on the side away from me.
Perce
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