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rrunkle 01-30-2012 09:58 AM

Phantom voltage
 
I have an unusual problem that I think might be similar to the one in this thread, but wanted to throw it out and get opinions.

http://www.diychatroom.com/f18/do-i-...roblem-112105/


Mine is more like this though:

House is only 5 years old. I'm working on finishing the basement, and am trying to clean up some of the old wiring, and PULL (remove) some of the wiring that I have now bypassed, by rewiring everything in the basement.

One of the wires that I'm trying to pull is an outside light that is switched in the basement, but runs straight up through the floor, and into my family room wall. I'm almost positive that it is going into an outlet box in my family room. It is heading rigth towards it.

So, I popped the breaker for the family room, and everything seemed to be dead. Nothing showed 120v. I disconnected the light in the basement at the switch and left all wires hanging loose. Then, I went up to the family room, and dug into the suspect outlet.

Coincidentally, this outlet just happens to be a switched outlet, with the tab broken to split it. So, there are are two loads going into the outlet (one hot, and the other switched). And, sure enough, there DOES seem to be an additional set of wires going into that outlet - I assume the light from downstairs. I disconnected all the black and whites, and as I was tinkering around with the wires, I got a little zap. Not a full 120v zap, but a little zap. Keep in mind that all the blacks and whites were separated, and all three of the wires downstairs were separated, and not touching anything else. NOTE: The one thing that I did NOT separate at this point was the grounds upstairs. I left the grounds bundle in the outlet box together, and never did separate them.

So, I started to probe around with my MM to see what was zapping me. I probed a ground to each wire (blacks and whites) in the outlet box. As I probed, I noticed that BOTH the black and white wires from what I thought was the light going stairs were showing voltage (keep in mind, with a digital MM, not analog). They would show erratic voltage, but if I held the connection, they would eventually settle down to almost exactly 64 volts. Both on the black and the white.

The really weird thing is that I went downstairs and did the exact same thing. I probed downstairs also (each the black and the white to the ground wire), and both showed that 64 volts.

To make things even more complicated, I have quite a bit of X10 equipment in my house, much of it with onboard LEDs in the switches. So, I'm suspect that I might be getting some trickle through some of that equipment.

Finally, I had a thought that maybe an adjacent circuit might be bleeding into my circuit. So, I popped the breaker right next to the family room one. This also, just happens to be the circuit for the "kitchen nook" which is right next to where the switch is located for this outlet. When I did that, all of my phantom voltage was gone.

I shrugged my shoulders, and put it all back together. Decided not to try and pull that wire after all.

Any thoughts?
To summarize:
1) All wires disconnect at both ends (EXCEPT the ground at one end) and still getting 64 volts on all black and whites to ground.
2) Enough of a charge to give a little zap, but nothing like a full load (120 v) zap.
3) Suspect trickle through X10 equipment, and somehow related to the adjacent breaker.
4) Been using a Digital MM to probe. But, the voltage is real enough to zap.

Thanks!

plummen 01-30-2012 10:23 AM

Sounds like an open neutral by the voltage anyway,could the light be powered from a circuit other than the basement ?

rrunkle 01-30-2012 10:26 AM

I forgot one more thing that I did...

While I was trying to find out which pair of wires was the ones that were going from the basement, I shorted out the pair (black to white, left ground free) to each other in the basement. Then, I went upstairs, and although the resistance was somewhat erratic, it did seem to eventually settle to just a few tenths ohms.

During this period when I had those wires in the basement shorted (and NOT hooked to anything upstairs. I turned on all my breakers. And, the breakers did not pop.

So, even though I have this phantom 64 volts running through that line, it did not cause any of my breakers to pop when the black/white were shorted together at one end.

Keep in mind that when I turned the breaker back on, all of the wires upstairs were separated, nothing connected to the outlet, and all bundles (except the grounds) were separated.

Thanks!

rrunkle 01-30-2012 10:32 AM

Quote:

Originally Posted by plummen (Post 839121)
Sounds like an open neutral by the voltage anyway,could the light be powered from a circuit other than the basement ?

What do you mean by "open neutral"?

And, when you say, "could the light be powered from a circuit other than the basement," do you mean, "could I leave this wiring in place, still connected to the outside light, powered from that family room outlet?"

If that is what you are asking, then yes, technically I could leave the wiring connected, but I would have to add a junction box. Luckily, I'm doing a drop ceiling, and could add a JB in the drop celing, then, run new wires down to my new switch box in the basement and hook it all up essentially the same as it is now. But, I'd rather clean it all up, and take some of that load off of the family room. Plus, I hate leaving that mysterious junction box in the drop ceiling. I can just imagine Mike Holmes (from Holmes Inspection) visiting my house in 20 years, and grumbling about the idiot that left all these junction boxes in the drop celing. :)

plummen 01-30-2012 10:39 AM

No i was just wondering if it was fed from a differant area you dont know about. :)
Usually when i see voltage readings like the ones youre talking about its when you have a power wire but the neutral wire is disconnected someplace ,usually youll get voltage readings in the mid to upper 60s when this happens:)

rrunkle 01-30-2012 10:47 AM

Quote:

Originally Posted by plummen (Post 839134)
No i was just wondering if it was fed from a differant area you dont know about. :)
Usually when i see voltage readings like the ones youre talking about its when you have a power wire but the neutral wire is disconnected someplace ,usually youll get voltage readings in the mid to upper 60s when this happens:)

It is possible that it is connected somewhere else. That is one of my theories, but I have doubts.
1) When I shorted the white/black in the basement and all wires in the outlet box disconnected and reset the breaker, nothing popped.

I have a weird feeling that the phantom voltage is actually coming from my grounds. Since, the only thing that I did not disconnect was that ground pigtail bundle in the outlet box.

And, I also have a very strong feeling that it is my X10 equipment (with LEDs) that is allowing the trickle.

plummen 01-30-2012 10:59 AM

Its definately possible,but without being there to see your problem firsthand all i can do is give you ideas of what to check :(

rrunkle 01-30-2012 11:41 AM

Quote:

Originally Posted by plummen (Post 839142)
Its definately possible,but without being there to see your problem firsthand all i can do is give you ideas of what to check :(

Let me ask a question:
Is it "code" to have supply from two breakers enter into a single switch box? The reason that I ask is that I have a suspicion that my phantom is coming from a switch box that might have supply coming from both of the "family room" and the "kitchen nook" circuit breakers (into the same box). In that switch box, I'm using two X10 switches. These switches have connects for white and also for ground. And, the X10 switches have LEDs, so they are powered.

I'm not positive that this switch box has two circuits going into it. But, if that is the case, I'm wondering if somehow I've now joined these two circuits, by pigtailing grounds or whites? I can check that switch box tonight to see which breaker it is running off, or if it is both.

zappa 01-30-2012 11:56 AM

I have been following this thread but it's difficult to know where you are measuring with your meter but I wanted to point out something that may help. There is such a thing as a MWBC which is 2 hot circuits that share the same neutral. The breakers are normally right next to each other and sometimes tied together but not always. Just a thought that may or may not be the case here.

The other circuit would use the red in a XX3/w ground cable.

rrunkle 01-30-2012 01:20 PM

Quote:

Originally Posted by zappa (Post 839171)
I have been following this thread but it's difficult to know where you are measuring with your meter but I wanted to point out something that may help. There is such a thing as a MWBC which is 2 hot circuits that share the same neutral. The breakers are normally right next to each other and sometimes tied together but not always. Just a thought that may or may not be the case here.

The other circuit would use the red in a XX3/w ground cable.

Zappa... I've aheard of that. My brother in-law recommended doing this when I was thinking about running two dedicated outlets in my basement. To save running two lengths of wire a long distance.

But, I am about 95% sure that none of my breakers have the red wire coming in. I'll check tonight though.

rrunkle 01-30-2012 11:25 PM

I think that I have found the root cause. Not sure why it is leaking into a disconnected wire, but I'm pretty sure that I'm on the right path.

I found out tonight that I have one switch box in my kitchen that has two breakers feeding it. One is the family room breaker, going to one of the switches. And , the other is the kitchen nook breaker going to the other switch. For both of these switches, if have lighted switches, which wire to black as well as white. And, I'll bet money that I've bundled the whites and grounds together inside the box. I'll have to check it later.

But, with lighted switches, I'm sure that I'm getting voltage leak through the switches from one circuit to the other. I'll have to separate them, and see what happens. Then, see if I can get that basement wire disconnected from the outlet in the family room after all.

zappa 01-31-2012 12:02 AM

That sounds like a logical explanation. Do lighted switches use neon lamps?

rrunkle 01-31-2012 09:38 AM

Quote:

Originally Posted by zappa (Post 839897)
That sounds like a logical explanation. Do lighted switches use neon lamps?

The lights are LEDs.

zappa 01-31-2012 09:47 AM

Quote:

Originally Posted by rrunkle (Post 840130)
The lights are LEDs.

Thanks, just wondering what they use nowadaze.

rrunkle 02-06-2012 01:46 PM

I haven't gone into the family room outlet to confirm that the leakage is gone. But, I did investigate the switch box in the kitchen. And, I did confirm that I had pigtailed the neutrals from both of the breakers together at one of the switchs. That, combined with the fact that my switches are lighted (LEDs), I'm pretty sure that this was the cause for the leakage into that family room outlet. I'll investigate that outlet tonight to see if the phantom volts are gone.


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