# 3way circuit with LED lights



## Geno52 (Aug 30, 2009)

I have two 3way lighting circuits (120v)in two different houses that are wired correctly. With incandescent bulbs they work fine. With LED bulbs they work fine but in the off position the LED bulbs are still putting out a faint light.
Is there still voltage on the circuit in the off position??
If so does this damage the bulbs?
Geno


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## 480sparky (Sep 20, 2007)

Are either of the 3-ways illuminated switches, or otherwise have electronics in them?


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## Dennis Alwon (May 9, 2009)

Geno52 said:


> I have two 3way lighting circuits (120v)in two different houses that are wired correctly. With incandescent bulbs they work fine. With LED bulbs they work fine but in the off position the LED bulbs are still putting out a faint light.
> Is there still voltage on the circuit in the off position??
> If so does this damage the bulbs?
> Geno


Some LED units need a driver and a special dimmer to work appropriately. What brand dimmer are you using?


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## MDShunk (Jan 7, 2007)

Google up "RC Time Constant". The LED's draw such low power that they take a long time to "drain" the circuit. The fix is a 7 watt night light bulb on that switch leg in the attic or basement.

Another choice would be a 20,000 ohm, 1-watt resistor wirenutted hot to neutral at one of the fixtures. http://www.parts-express.com/pe/showdetl.cfm?partnumber=003-20K


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## busymnky (Feb 16, 2009)

Nice answer Marc!


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## Geno52 (Aug 30, 2009)

One of the 3 way circuits is actually a four way and it has the leviton swithes with the lights in them. The other is a 3way and has no lights or electronics in the swithes. Each one is using a different brand of LED bulb. There are no dimmers. I know that LEDs will glow for a while but these stay dim until you turn it back on.
GEno


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## MDShunk (Jan 7, 2007)

Geno52 said:


> I know that LEDs will glow for a while but these stay dim until you turn it back on.
> GEno


I have no trouble at all believing that, since induction can light even a neon lamp of a 3-light receptacle tester. The LED draws even less current than the neon's do. Your 3-ways are done with 14-3 (probably), and the hot wire is wrapped around your switch leg like a big long 1:1 transformer.


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## Geno52 (Aug 30, 2009)

The house here in the US is wired with romex but the one in Mexico is wired with #12 stranded in conduit. This one is the one with the lighted levitons. If there is no way to completely turn it off is it hurting the lights??
Geno


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## MDShunk (Jan 7, 2007)

Geno52 said:


> If there is no way to completely turn it off is it hurting the lights??


Nope.


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## partimer31 (Jun 9, 2009)

"Nope" from MDShunk

and why would it hurt the bulb? :thumbsup:


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## MDShunk (Jan 7, 2007)

partimer31 said:


> and why would hurt the bulb? :thumbsup:


Me Tarzan. You Jane. :jester:


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## partimer31 (Jun 9, 2009)

:laughing: :laughing:


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## electricalperson (Jan 11, 2008)

i believe this can be called phantom voltage. put a high impedance multimeter on the dead switchleg and see if you get a voltage. then put a wiggy or lightbulb in paralell and see if the lights turn off


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## mikheil (Sep 7, 2009)

I agree with the inductance theory by the shunk man.. totally plausible.

try putting a switch (just for testing purposes) on the neutral line, in addition to the switch already in the phase line. when turning both switches off, the LEDs should turn off completely.

the RC time constant theory is definitely not the issue. you would see its effect if you had a high speed camera to monitor the LED's as power is turned off...

besides, from what the post implies, the LEDS are constantly on, as opposed to slowly turning off..


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## drsparky (Nov 13, 2008)

mikheil said:


> I agree with the inductance theory by the shunk man.. totally plausible.
> 
> try putting a switch (just for testing purposes) on the neutral line, in addition to the switch already in the phase line. when turning both switches off, the LEDs should turn off completely.
> 
> ...


If you use an analog meter like a Simpson 260 you can see the needle move 5 times as the capacitor discharges. I used to time it with a stop watch to determine the size of a capacitor.


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## mikheil (Sep 7, 2009)

drsparky said:


> If you use an analog meter like a Simpson 260 you can see the needle move 5 times as the capacitor discharges. I used to time it with a stop watch to determine the size of a capacitor.


sure thing, but how large of a capacitance do you think a 12-3 NM would generate!! i'm thinking somewhere in the order of a few pF which means you wouldn't see it discharging unless you had a high speed camera!!


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## josh5879 (Sep 21, 2009)

Geno52 said:


> One of the 3 way circuits is actually a four way and it has the leviton swithes with the lights in them. The other is a 3way and has no lights or electronics in the swithes. Each one is using a different brand of LED bulb. There are no dimmers. I know that LEDs will glow for a while but these stay dim until you turn it back on.
> GEno


Correct me if I'm wrong but isn't the problem simply with the lighted switch? Remember there's no neutral on those switches, they just use a resistor going to a bulb that is wired in parallel with the switch. When the switch is off, there still is a small current passing through the switch bulb and the circuit is completed by the light bulb.
Now that's fine with an incandescent bulb,it just goes through the filament no problem, and it's not nearly enough to light it up. But with LED bulb or for that matter sometimes CFL it might light up a bit.
That's it, just change the four way switch to a regular switch w/o a light and you should be fine. Or maybe you can find a lighted switch with a separate neutral.


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## Toronto Sparky (Apr 12, 2009)

Same thing happens with two wire motion detectors being used on electronic loads.


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## LJSMITH1 (May 4, 2009)

I am pretty sure it's the illuminated switch. BTW - The light in the switch also doesn't work when there is a missing/burnt bulb in the fixture. 

When the switch is in the "off" position, the illuminated switch does something that may seem odd: instead of cutting the current to the light fixture, it simply _reduces_ the current, so that its internal light (typically an LED or, in the case of older models, a neon bulb) can use the current passed through:

Without this current passing through, the illuminated switch would not be able to illuminate. Since the current to the light fixture is significantly reduced when the switch is "off," a normal incandescent bulb will not light. However, there is current passing through the bulb. To prove this, you can unscrew the bulb and see whether the illuminated switch stays illuminated. Most of the time, removing the light bulb will cause the switch itself to go dark.

Even though there's not enough current passing through to light an incandescent bulb, many compact fluorescent lights or LED's are sensitive enough to small amounts of current that they will flicker on and off, or even maintain a constant dim glow, when the lighted switch is "off."

Put a standard switch in its place and the problem will go away.:thumbsup:


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## josh5879 (Sep 21, 2009)

Thank you LJSMITH1 for explaining my original post more clearly. 
I don't know why this tuned into a whole discussion on inductance theory and phantom voltage.


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