# LED Christmas Light Glow When Outlet Is Switched Off-Phantom Voltage



## velvetfoot (Dec 16, 2015)

Really weird.  They glow very faintly even when the switched outlet is off.  I checked voltage at the outlet between and got 47 volts from the hot leg to both ground and neutral.  I also got around 40 volts in three others switched outlets on different breakers, although I didn't see lights glow when I plugged them in (it is daytime though).  An outlet tester checked out, no voltage between neutral and ground, checked tightness of neutrals in box.  What is interesting is that voltage persists even when I totally disconnect the switch!  That's where I'm at now.

Could there be a generic issue with the outlets?  Inductance in wire run?


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## DougA (Dec 16, 2015)

You've got a wiring problem. I can't recall exactly what causes this but I have had that problem when I wired something wrong.  Rare to see that on an outlet. Wondering if there is a switch, especially a 3 or 4 way switch on the same circuit?  If there is, the switch is the cause.


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## velvetfoot (Dec 16, 2015)

No other switch.  Bear in mind, I'm seeing the same effect of voltage on switched off outlets on 4 different circuits, although I haven't plugged in the Christmas lights at night yet.
The plug in outlet tester checks out.  

These outlets are switched on top and unswitched on bottom.  I might try replacing an outlet.


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## sportbikerider78 (Dec 16, 2015)

Drop breakers till the voltage is gone.  Then bring them back in reverse order.  You'll find which one it is and then start popping out the outlets.


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## velvetfoot (Dec 16, 2015)

?????
I know which breakers the switches are on.


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## sportbikerider78 (Dec 16, 2015)

Aren't you trying to figure out where the voltage is coming from?  What i'm suggesting is turning other breakers off until you see that phantom voltage disappear.  Then you can start looking at how the other outlets around the problem system are wired...and hopefully find out whats going on.


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## DougA (Dec 16, 2015)

What he is saying is that the problem could easily be caused by wiring on another breaker circuit. I'd actually go in reverse and start with everything off and turn one at a time on and read each time.  If it's only a problem with just the one breaker on, then you take step #2 and isolate the wiring coming off that breaker.  
My money is still on a switch that is wired wrong but finding it is a PITA.


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## kennyp2339 (Dec 16, 2015)

Induced voltage my friend, do you have any transmission lines going over you property?


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## velvetfoot (Dec 16, 2015)

LOL, no.


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## Highbeam (Dec 16, 2015)

The other fun thing that can cause this is a wire staple pounded too hard that makes a weak connection between the hot and neutral or hot and ground. Doesn't matter which since they are joined at the main panel.

That 47 volts is a leakage of power that is stealing your money. It is a little short circuit that is not quite big enough to pop the breaker. 47 volts is enough to feel the zap.


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## Ashful (Dec 16, 2015)

velvetfoot said:


> Really weird.  They glow very faintly even when the switched outlet is off.  I checked voltage at the outlet between and got 47 volts from the hot leg to both ground and neutral.  I also got around 40 volts in three others switched outlets on different breakers, although I didn't see lights glow when I plugged them in (it is daytime though).  An outlet tester checked out, no voltage between neutral and ground, checked tightness of neutrals in box.  What is interesting is that voltage persists even when I totally disconnect the switch!  That's where I'm at now.
> 
> Could there be a generic issue with the outlets?  Inductance in wire run?


Several rooms in my current house were wired with neutral switching, instead of hot switching.  This can cause fun stuff like this, but it's more often a badly balanced box combined with a grounding problem.  Post back with voltage between each pair (hot/neutral, neutral/ground, hot/ground), with switch both on and off.

sportbikerider78's recommendation in post #4 is a good one, if you have a second person available to switch off breakers while you stand monitoring the offending receptacle.  Obviously, leave the breaker to the offending receptacle on, while you do this.


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## velvetfoot (Dec 16, 2015)

But, while there's some voltage there, I don't think the current is.

The outlet's ground and neutral are at zero potential, so it would seem that the voltage is coming from the hot wire.  I totally disconnected the switch, which supplies the hot wire, and the voltage at the outlet is still there.  I can only think that somehow there is a leakage at the outlet (the top half is switched, the bottom half is always hot).


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## greg13 (Dec 16, 2015)

velvetfoot said:


> But, while there's some voltage there, I don't think the current is.
> 
> The outlet's ground and neutral are at zero potential, so it would seem that the voltage is coming from the hot wire.  I totally disconnected the switch, which supplies the hot wire, and the voltage at the outlet is still there.  I can only think that somehow there is a leakage at the outlet (the top half is switched, the bottom half is always hot).



Are BOTH connector tabs between the screws removed?


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## seige101 (Dec 16, 2015)

How old is the house/wiring  and what type of wiring? Old romex or cloth covered romex? Old BX?


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## velvetfoot (Dec 16, 2015)

Ashful said:


> Several rooms in my current house were wired with neutral switching, instead of hot switching. This can cause fun stuff like this, but it's more often a badly balanced box combined with a grounding problem. Post back with voltage between each pair (hot/neutral, neutral/ground, hot/ground), with switch both on and off.


I don't think I'm switching the neutral.  The switch box seems to be wired correctly, and besides, the outlet test (a plug in thing with 3 leds) checked out.

On
hot/neutral: 119.2, neutral/ground: 0, hot/ground: 119.2

Off
hot/neutral: 47.9, neutral/ground: 0, hot/ground:  47.9


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## velvetfoot (Dec 16, 2015)

greg13 said:


> Are BOTH connector tabs between the screws removed?


I'll probably look a little closer tomorrow.  Maybe try taking things apart to come up with a cause.  I bought a couple of outlets (there are two on the switch) to maybe replace.


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## velvetfoot (Dec 16, 2015)

seige101 said:


> How old is the house/wiring  and what type of wiring? Old romex or cloth covered romex? Old BX?


It's about 10 years old or so.


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## DougA (Dec 16, 2015)

greg13 said:


> Are BOTH connector tabs between the screws removed?


If it's a switched outlet with one always live and one live via switch, you would only need to remove one tab, the hot lead tab, since the neutral wires can be shared. Hot lead for always live goes to one end of outlet, hot lead for the switched end goes to switch, then to other end of outlet. 
I'm not a certified electrician so take my advice knowing that.


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## seige101 (Dec 16, 2015)

Very odd. I have seen that problem with older wiring. The insulation breaks down and you get a "phantom" voltage at switched plugs or light fixtures. Not noticeable with an incandescent lamp but throw an led or cfl in there and you get a small glow from the fixture or the occasional strobe effect.

Can you try removing all the wires from the outlet and also the switch and test for voltage again. This will determine if it's the outlet somehow leaking from the switched half to the constant half. If you are still getting voltage i would suspect the 3-wire in the walls is somehow compromised either an over driven staple or the insulation got caught on something during initial install.

Are the switch boxes metal or plastic? Is metal it could also be possible that the metal clamps in the box were over tightened compromising the insulation.

Wish you were a little bit closer, i love troubleshooting that kind of stuff


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## velvetfoot (Dec 16, 2015)

seige101 said:


> Can you try removing all the wires from the outlet and also the switch and test for voltage again.


Earlier, I removed all wires from the switch (not the outlet).  I'll try removing stuff in steps tomorrow, maybe, to attempt to narrow in on it.  It's weird that 3 other half-switched outlets on 3 other circuits also exhibit voltages.

Boxes are plastic.

I never would have noticed if I hadn't plugged in the led Christmas lights.


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## Ashful (Dec 16, 2015)

velvetfoot said:


> On
> hot/neutral: 119.2, neutral/ground: 0, hot/ground: 119.2
> 
> Off
> hot/neutral: 47.9, neutral/ground: 0, hot/ground:  47.9




Is this a solid state dimmer switch, or a true mechanical switch?  The voltages you report look like what you might see in the case of a solid-state switch (think X-10 dimmer module, or similar).  As soon as you load it, voltage drops to near zero, but LED Christmas lights provide very little load.


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## velvetfoot (Dec 16, 2015)

Ashful said:


> Is this a solid state dimmer switch, or a true mechanical switch?


A true mechanical switch.


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## greg13 (Dec 16, 2015)

DougA said:


> If it's a switched outlet with one always live and one live via switch, you would only need to remove one tab, the hot lead tab, since the neutral wires can be shared. Hot lead for always live goes to one end of outlet, hot lead for the switched end goes to switch, then to other end of outlet.
> I'm not a certified electrician so take my advice knowing that.


My thinking is that since there is a problem somewhere, by removing both tabs you are totally isolating the two halves of the outlet. there would be no way to get any crossover.


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## velvetfoot (Dec 16, 2015)

The hot supply to the switched outlet is from the switch, and there is no neutral wire along with the wires from the switch to the outlet.  The neutral would have to come from the unswitched outlet.


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## DougA (Dec 16, 2015)

greg13 said:


> My thinking is that since there is a problem somewhere, by removing both tabs you are totally isolating the two halves of the outlet. there would be no way to get any crossover.


That makes sense but he's saying twice that other outlets are also a problem. " It's weird that 3 other half-switched outlets on 3 other circuits also exhibit voltages."  Somebody has a crossed wire or as others posted, a nail or screw in a wire.  The only way to trace something like this is to isolate circuits and go one step at a time - very time consuming.
I had a drywaller once put too long a screw into drywall and it was only found by isolating every line and running a wind-up voltage tester of some kind that created a current. That was 30 yrs ago and I'm sure they have electronic ones now.  Wiring errors can be very frustrating.


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## DougA (Dec 16, 2015)

velvetfoot said:


> The hot supply to the switched outlet is from the switch, and there is no neutral wire along with the wires from the switch to the outlet. The neutral would have to come from the unswitched outlet.


That's how it should be done IMHO.  Unless the switch is super convenient and it would save labor to do otherwise, an electrician won't run any more copper than necessary. I've got a few half switched outlets in my house and they are great for turning on room lights when you enter the room. Many people don't want room lights on the ceiling.


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## velvetfoot (Dec 16, 2015)

DougA said:


> " It's weird that 3 other half-switched outlets on 3 other circuits also exhibit voltages."


Each of the circuits is on its own breaker.  There is no voltage to the switched outlet when its breaker is opened.  Neutral is not open.


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## DougA (Dec 16, 2015)

velvetfoot said:


> Each of the circuits is on its own breaker. There is no voltage to the switched outlet when its breaker is opened. Neutral is not open.


That's why a few of us are suggesting that you have to turn off the breakers one at a time and test, or as I suggest turn all off, then one on at a time. Since all the neutrals and ground wires are tied together to neutral/ground lugs on a panel, if you have a hot/neutral or a hot/ground fault somewhere in the house, it will affect all your neutral or ground circuits. Yup, it gets messy.


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## xman23 (Dec 16, 2015)

It's not uncommon to have inductive or capacitive coupling from live wiring that's run parallel. With high impedance devices, such as LED,s as the only load, they will glow. That's why and how transformers work. Turn off the main breaker to the house and see.

But as others have said you can do some strange things with back feeding the neutral.


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## Ashful (Dec 16, 2015)

xman23 said:


> It's not uncommon to have inductive or capacitive coupling from live wiring that's run parallel. With high impedance devices, such as LED,s as the only load, they will glow. That's why and how transformers work. Turn off the main breaker to the house and see.


A definite problem in communications circuits, or with high transient loads, but I do not believe a 60 Hz line is going to couple sufficient CW power to an adjacent line, given spacing between hots and grounds versus potential spacing between adjacent Romex pairs, with any less than 12 million feet of parallel length.


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## DougA (Dec 16, 2015)

Have to agree on that. It might make an LED glow but not put 40+ volts on a meter.


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## velvetfoot (Dec 16, 2015)

Again, I never would've noticed if I didn't plug in the led Christmas lights.


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## semipro (Dec 17, 2015)

DougA said:


> it was only found by isolating every line and running a wind-up voltage tester of some kind that created a current.


One common name for the device typically used now is "fox and hound".   I believe you can even rent them in some places.


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## Ashful (Dec 17, 2015)

DougA said:


> Have to agree on that. It might make an LED glow but not put 40+ volts on a meter.


Actually, other way around.  Meter has very high impedance, so 41 volts is surely less than 1 mW.  By comparison, it will take 7000 mW to get a full string of 100 LEDs to full brightness, so depending how bright they're glowing...


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## DougA (Dec 17, 2015)

While lying in bed last night, I remembered where I had the 40-50v. reading. I was replacing some 3 and 4 way switches with the newer style and got confused about which wire went where. Often they use red or yellow on these lines. I got out the meter and got a reading of 40 -50v but I can't recall how that happened.  That's why I suggested that the voltage might be related to a mis wired switch.  I still get dizzy when I do 3 way and 4 way switches.


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## velvetfoot (Dec 17, 2015)

Ashful said:


> how bright they're glowing...


Very, very dim.


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## DougA (Dec 17, 2015)

The LEDs are irrelevant, other than that's how you discovered your short.  40+v is the problem.  It won't kill anyone touching it but it's enough to cause problems.  Then again, 120v won't kill anyone either, unless they are grounded - at least ASAIK. I've felt 120 plenty of times and it wakes you up.  I know someone that had his arm stuck into an industrial conduit where the power was supposed to be off - he lived but had a 3 month vacation recovering.


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## Ashful (Dec 17, 2015)

I work on systems delivering up to 80 kW into 50 ohm loads (capable of 4 kV continuous RMS voltage), every day.  I've hit myself with > 120V probably more times than I can count.  Only hurts when you're sweating.  

Ever light a lightbulb sitting on a table from across the room?


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## DaleZ (Dec 17, 2015)

I believe you're in my general area and the other day we had an hour or so brown out with power at less than 80 volts. Not sure if this could of messed something up or if your house was even involved. Just a thought.

Dale


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## DougA (Dec 17, 2015)

Ashful said:


> Ever light a lightbulb sitting on a table from across the room?


clap on clap off.


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## velvetfoot (Dec 17, 2015)

DaleZ said:


> I believe you're in my general area and the other day we had an hour or so brown out with power at less than 80 volts. Not sure if this could of messed something up or if your house was even involved. Just a thought.
> 
> Dale


Nothing here.  NYSEG trimmed the trees not too long ago and I think they also put a recloser on our line.  Of course, that means instead of the entire line going out, it's just us and our neighbors, lol.


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## Ashful (Dec 20, 2015)

What was the findings, turning off breakers one at a time?


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## velvetfoot (Dec 20, 2015)

Did that.  Just one breaker, the one the lights are on is affected.  I disconnected wires at outlets, and MIGHT have isolated it to a 4' piece in the wall from switch box to outlet.  The reality was that it was getting dark, Mrs. Velvetfoot was bitching at me, and I put it all back together with new outlets.  Still a very faint glow.  Note that I measured voltage on three other half-switched outlets in the house, each on their own breaker.  Tearing up walls, chasing ghosts, not in the outlook.


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## brenndatomu (Dec 20, 2015)

I have been watching this one with interest. I have run into this problem in the past and it usually ends up being from induced voltage. Sounds like you probably have a string of wires running together. Good news is that normally it doesn't really cause an actual problem.


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## jrems (Dec 20, 2015)

I have seen this many times. Is the on off wall switch lighted? If it has a light inside( so you can see the switch at night) these type of switched will cause leds to light very dimly. No one brought it up before or asked. It's not a wiring issue and no cause for concern if it is the issue, it's a known bug with leds


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## velvetfoot (Dec 21, 2015)

No, not a lighted switch.


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## Ashful (Dec 21, 2015)

velvetfoot said:


> No, not a lighted switch.


That's a shame.  When I saw that post, I figured jrems had nailed it.


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## burnham (Dec 24, 2015)

brenndatomu said:


> I have been watching this one with interest. I have run into this problem in the past and it usually ends up being from induced voltage. Sounds like you probably have a string of wires running together. Good news is that normally it doesn't really cause an actual problem.



If it's an induced voltage, why does the problem go away when he turns that breaker off?


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## kennyp2339 (Dec 24, 2015)

burnham said:


> If it's an induced voltage, why does the problem go away when he turns that breaker off?


Because it's not induced voltage like a few of us thought, he also has a lighten switch which was leaking voltage which was enough for the LEDs to have a phantom glow.. Merry Xmas


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## velvetfoot (Dec 24, 2015)

kennyp2339 said:


> he also has a lighten switch


Lighted switch?  No.


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