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Old 06-08-2012, 07:04 PM   #1
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Phantom voltage?


I replaced a light bulb on one of my switched outlets with an LED and noticed the bulb was dimly lit when the switch was off. I used my DMM and it shows 60 volts when off and 120 when on. My builder said it's not an issue as it's phantom voltage and that everything is okay. Do you guys agree with that?

I checked another switched outlet in my house and it had the same thing (60 volts and the LED bulb would come on dimly lit).

Thanks for your time and assistance.

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Old 06-08-2012, 07:07 PM   #2
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Phantom voltage?


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Originally Posted by mashean View Post
I replaced a light bulb on one of my switched outlets with an LED and noticed the bulb was dimly lit when the switch was off. I used my DMM and it shows 60 volts when off and 120 when on. My builder said it's not an issue as it's phantom voltage and that everything is okay. Do you guys agree with that?

I checked another switched outlet in my house and it had the same thing (60 volts and the LED bulb would come on dimly lit).

Thanks for your time and assistance.
Almost certainly this is not a phantom voltage.

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Old 06-08-2012, 07:15 PM   #3
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Phantom voltage?


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Almost certainly this is not a phantom voltage.
I agree... an issue exist somewhere. Open or loose neutral connection would be a good guess.

Last edited by stickboy1375; 06-08-2012 at 07:27 PM.
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Old 06-08-2012, 07:30 PM   #4
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Phantom voltage?


What kind of switch do you have? Old style no frills off/on or a modern lighted or motion switch.
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Old 06-08-2012, 07:40 PM   #5
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Phantom voltage?


Zappa, one is a standard on/off switch and the second is a dimmer switch. The house is 2 years old
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Old 06-08-2012, 07:49 PM   #6
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Phantom voltage?


I would expect it to stay partially lit on the dimmer circuit. I know it's crazy but the LED's don't take much to make them glow. Do they immediately go out if you unscrew it?
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Old 06-08-2012, 07:56 PM   #7
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Phantom voltage?


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I would expect it to stay partially lit on the dimmer circuit. I know it's crazy but the LED's don't take much to make them glow. Do they immediately go out if you unscrew it?
So where is the 60v coming from? That is the question.
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Old 06-08-2012, 08:06 PM   #8
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Phantom voltage?


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Zappa, one is a standard on/off switch and the second is a dimmer switch. The house is 2 years old

Well you might be able to come up with a leakage current theory for the dimmer such as it isn't fully off as in the slider won't go to zero), or the triac inside is damaged and leaking current when off, or it is a smart switch that draws a trickle of power to run its internal electronics.

The fact this also happening for the mechanical switch is saying something very strange. There is no phantom voltage leakage current theory if the current is physically open circuit. Are you sure there isn't a 3 way in the switch path and it is some type of electronic switch paired up with the mechanical switch?

Last edited by curiousB; 06-08-2012 at 08:10 PM.
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Old 06-08-2012, 08:17 PM   #9
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Phantom voltage?


You could substitute a non-electronic household toaster for the bulb and measure the voltage again. And measure the resistance of your toaster - it should be about 10 ohms.
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Old 06-08-2012, 08:32 PM   #10
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Phantom voltage?


Edit out.

Last edited by zappa; 06-08-2012 at 08:37 PM.
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Old 06-08-2012, 08:37 PM   #11
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Phantom voltage?


THe ordinary switch (or at least one of a pair of 3-ways) does not have a night light inside it does it? That could cause a low wattage light such as an LED lamp to come on.
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Old 06-08-2012, 10:10 PM   #12
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Phantom voltage?


Thanks for your thoughts. The mechanical switch is just an on/off switch without a light of any sort. The dimmer also has a switch but also the sliding dimmer part where I can adjust. The switch does turn it off completely and there aren't any lights on it either. I've placed a couple books on hold at the library regarding electrical so I'll read through them to get a better understanding of how things should work and how to verify they're as they should be. Odd my builders electrician says its normal.
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Old 06-08-2012, 10:20 PM   #13
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Phantom voltage?


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Originally Posted by mashean View Post
Thanks for your thoughts. The mechanical switch is just an on/off switch without a light of any sort. The dimmer also has a switch but also the sliding dimmer part where I can adjust. The switch does turn it off completely and there aren't any lights on it either. I've placed a couple books on hold at the library regarding electrical so I'll read through them to get a better understanding of how things should work and how to verify they're as they should be. Odd my builders electrician says its normal.
The funny thing is how he calls it phantom voltage yet the light is dim... well I guess its not really phantom now is it? Im still going with open neutral... but time will tell on this one.
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Old 06-09-2012, 10:14 AM   #14
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Phantom voltage?


Just a guess but it could be an ungrounded RFI filter in a TV, microwave or computer dividing the 120v by two and putting it on the neutral.

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