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

[velvetfoot]

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?

 

[DougA]

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.

 

[velvetfoot]

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.

 

[sportbikerider78]

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.

 

[velvetfoot]

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

 

[sportbikerider78]

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.

 

[DougA]

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.

 

[kennyp2339]

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

 

[velvetfoot]

LOL, no.

 

[Highbeam]

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.

 

[Ashful]

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.

 

[velvetfoot]

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).

 

[greg13]

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?

 

[seige101]

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

 

[velvetfoot]

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

 

[velvetfoot]

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.

 

[velvetfoot]

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.

 

[DougA]

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.

 

[seige101]

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

 

[velvetfoot]

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.

 

[Ashful]

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.

 

[velvetfoot]

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

A true mechanical switch.

 

[greg13]

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.

 

[velvetfoot]

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.

 

[DougA]

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.