Stray voltage at light fixture ??

[PWC Repair]

I think I already know the answer but need to make sure. My house was built in the 50's. I've remodeled most of it and just finishing up a bedroom remodel. I left one of the light fixtures exactly where it was and it has been working fine. I went to install our new LED light fixtures and as soon as I got the fixture up against the ceiling the LEDs all lit up very dimly. Pull it a couple inches away from the ceiling they shut off. Measuring with my meter I get about 2.5vac touching the insulation with one lead and other lead to ground (the old metal box). Light switch is off, breaker is on.......YES, I change things out while hot....Yes, I sometimes get bit. Anyway, I unhook the fixture and measure right across the wires and get 43vac. Then I unhooked one side of the light switch and STILL get 43vac. I'm remembering in other rooms I've remodeled they had broken the neutrals on lights and NOT the hot. I'm guessing that's the issue here and the new LED is too sensitive and wants the hot switched. No big deal as I have to wire a light in the new closet and stab a new 'bedroom' breaker anyway. Just want an opinion from somebody else that's seen this before. Thanks.

 

[cybrdyke]

whatever the source of the voltage, it's enough toget to the driver to fire the diodes. Doesn't take much with LED's. They're not "faulty" or "too sensitive". That's one of the characteristics of a new technology.
CD

 

[Innovate1]

The loading of the meter is almost nothing so will show some voltage when a wire is off but just run next to a wire that is hot even if insulation is fine. LEDs don't take much to make them glow dimly but more load than a meter. Do you have lighted switches? Those pass a small current through the bulb to light the switch when off and could make the LEDs glow. But I wouldn't expect moving the fixture from the ceiling to a few inches away to make a difference - the wires get shoved together which makes a very small difference in capacitive coupling but I doubt enough to notice in LED glow.

 

[PCustoms]

I'm guessing that's the issue here and the new LED is too sensitive and wants the hot switched.

How are your switches wired?

 

[American Locomotive]

How are your switches wired?

This.

It sounds like you're saying your light switches are on the neutral? Ignoring the fact that it's bad practice, switched neutrals (instead of hots) often allows LEDs to dimly glow when off. All of the neutral wiring between the fixture and the switch has just enough capacitive coupling to allow a very tiny amount of current to pass. This tiny amount of current is sometimes enough to make the LEDs glow dimly depending on how the fixture is designed.

 

[nadogail]

Neutrals are almost never Switched or Fused. The exceptions are Gas Pumps.

 

[PWC Repair]

How are your switches wired?

Everything I'VE remodeled is switched on hot. This one and 2 in the kitchen are switched on neutral.

This.

It sounds like you're saying your light switches are on the neutral? Ignoring the fact that it's bad practice, switched neutrals (instead of hots) often allows LEDs to dimly glow when off. All of the neutral wiring between the fixture and the switch has just enough capacitive coupling to allow a very tiny amount of current to pass. This tiny amount of current is sometimes enough to make the LEDs glow dimly depending on how the fixture is designed.

Yes, house was built in the 50's. I've been remodeling a bit at a time since I bought the house in 1998. Everything I've done involves gutting down to the studs, replacing all the cloth covered 2 wire with no ground, rewiring to junction boxes above each room then running a new 'home run' to the breaker panel, insulating as there was none in the walls and only antique R11 in the attic, new drywall, new windows, and refinishing the original hardwood floors.

So, if everybody is on the same page here then I guess I have "phantom" voltage because this switch is still on the neutral side and I'll be changing it. Agreed??

 

[PCustoms]

So, if everybody is on the same page here then I guess I have "phantom" voltage because this switch is still on the neutral side and I'll be changing it. Agreed??

More then likely, it's also a potential safety issue (though not as much with LED), so do it right.

 

[walta]

Is it possible the light switch has a neon light inside that lit up when the switch was off so people could find then in the dark room?

The neon lite seems likely to give the same symptom.

The old silent switches with a mercury contacts could also leak enough current to light the new LEDs.

Replacing the 70 year old light switch could not hurt.


Walta

​

 

[PWC Repair]

I'll be replacing the switch AND the wiring. There IS a neon lighted switch to the back deck on the same circuit but I also tried unhooking one side of it with no difference. It will also be getting changed.

Guys.....this isn't EVEN the half of it. I had been in the house for about 6-7 years and we remodeled the utility room (8.5x11ft). Mostly because my wife opened the 9x9 single pane wooden frame window and a couple of the small panes fell out and broke. The utility room also had 220v for the electric dryer in metal conduit down the wall and around the baseboard. Besides the whole room being 3/4" out of square......the exterior door was NOT double studded, and there were no headers or jack studs on those windows!!! Here's the BEST PART,...that 220v to the dryer.......2 pieces of 10ga wire and a COAX TV CABLE stripped and twisted together for the neutral!!!

 

[walta]

. My house was built in the 50's. Measuring with my meter I get about 2.5vac touching the insulation with one lead and other lead to ground (the old metal box)

In a 1950s house there would be no ground wire in the cable so the metal box could not be grounded.

Then I unhooked one side of the light switch and STILL get 43vac.

When one of the wires is disconected from the switch do the LEDs still glow?

Walt

 

[PWC Repair]

When one of the wires is disconected from the switch do the LEDs still glow?

Walt

Yes. I'll try to get a short video clip.

 

[walta]

Is your switch wired like the circuit A or B in the attached photos?



Walta

 

[PWC Repair]

Like B EXCEPT not breaking hot.....breaking neutral. Everything I've redone, I've wired like A.

 

[walta]

Like B EXCEPT not breaking hot.....breaking neutral. Everything I've redone, I've wired like A.

Please post a phot of the wire in the light fifture box.

Walta

 

[PWC Repair]

Sure......but it won't tell you anything. Just a cloth covered black and white end. From there it goes over to some crazy soldered and taped joints.....that jumper to more joints.......that jumper again.......it's just nuts! This is the last bit of craziness in the house before I finish up my 'home runs' then pull the old stuff out.

 

[PWC Repair]

I don't know.......I put the fixture back up tonight to get pics and a video......and it DID NOT dimly light up, nothing. Working normally. Just touching wires to insulation and pic of voltage. But yesterday i was reading 2.5vac. Then as I was trying to read to ground again........5vac! And then I realized my hand was against the metal on the fixture housing. WTH......apparently I can make enough voltage from my body to light these suckers! Then I went to the other side of the room, which is newly wired BUT NOT grounded yet as I still have to run to the breaker panel, and if I hook up the ground that fixture will also light up. That ground goes to NOTHING right now. Just nutted to other grounds from receptacles still waiting on my 'home run'. Uploading a video now.

 

[PWC Repair]

Video. Also, I can touch my wife's hand while she is just standing in the middle of the room, with shoes on, and light it up a bit brighter. And if I meter from an insulated wire to my free hand I can measure 10vac! What is going on here......?

 

[walta]

When I look at the photo of the ceiling box, I only see 1 black and 1 white wire correct?

If so, the power feed must be at the switch box like the A diagram.

Lets see a photo of the switch box.

Note I also do not see any ground wire connected to the electrical box so putting your meters probe on the box is pointless as it in not connected to anything.

Walta

 

[PWC Repair]

Ok, I've done more google searching and then put a slight load on the wiring.

Conclusion.....It's just EMI, phantom voltage, capacitive coupling, whatever you want to call it. Apparently the cheaper fixtures do NOT have complete off switching and THIS is what happens. My wife bought mid priced fixtures yesterday and they also did this. BOTH brands of fixtures had led boards made by Intertek. 2 different arrangements and 2 different part numbers. There is a little doo-hicky you can wire in your fixture to simulate a tiny load so the led completely goes off. We've decided to just change fixture styles with regular screw in bulbs.

 

[cybrdyke]

One tiny correction...Intertek is a 3rd party testing lab, like UL, not the manufacturer.
CD