# Voltage mystery

1186 Views 12 Replies 7 Participants Last post by  joed
Hi guys, I've got a puzzle that I'm trying to figure out. I have a JB with 2x 2 conductor lines coming into it. I suspect that there's a continuity issue on one circuit escaping thru the ground to another (or somewhere else.) I have tested the voltage across the 5 conductors with the following results:

H1 - N1 = 2.8v
H1 - H2 = 78.4v
H1 - N2 = 15.2v
H1 - G = 4.1v

N1 - G =3.5v
N1 - N2 = 15v

N2 - G = 24.2v

H2 - G = 95.7v

H2 - N2 = 120v

Any information you can give me is much appreciated. Thanks!
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You are most likely using a high impedance digital volt meter.
You are getting phantom voltage readings.

https://www.nema.org/Technical/Documents/Bull_88_reaffirmed_12_15_11.pdf
What issue were you trying to resolve by opening the connections and taking measurements?
I assume I have some crossed circuits; I have a room that requires two circuit breakers to be off. If one or the other is on, the boxes have power. I'm trying to figure out the best way to tackle that and taking these readings is my first idea, just trying to get an idea of what's going on. Thank you for your replies.

I used a victor VC890C+to check these.
One way to resolve that cross feed is to go to the farthest outlet on that circuit and disconnect the through feed and nut it off.
This is an older house with multiple renovations. I'm worried that there's a buried box somewhere that houses the problem. I have disconnected all the outlets in question. Several of the original circuits have no ground, and I know I've seen outlets further down that circuit that have a ground wired. Is it possible, in that case, for voltage to be travelling thru the ground/neutral wires? I appear to have a hot ground wire in a 3-way light circuit, from the feed line.
As Oso said, you are probably getting phantom readings. Those numbers are all over the place and useless to troubleshoot. Pick up an inexpensive analog meter, the type with a scale and needle indicator. Inexpensive will probably be a lower impedance that will nullify the induced voltage.

Bud
I appreciate the input, I checked with a different meter and got the same results. Would that be typical in PV?
It depends on what the other meter was. Phantom voltages are induced voltages that are created by wires being close together and no load to drain off that energy. LED and CFL bulbs often suffer from this and can flicker or even light when there is no real voltage applied.I've been testing electronic circuits for over 50 years and still prefer my standard analog meter. Digital meters give the illusion of being accurate, but not always the case.

But, no doubt you have a problem and your last reading was 120 volts, I like that one.

Can you tell us more about the wiring, two circuits seem to be powering that area,

Note, do not change any wires in the panel as currently the two circuits are on the same side of the 240 volts.

Let some of the pros see what they can suggest.

Bud
It was digital too, lol. I'll get the analog meter tomorrow and post the results.

The wiring was originally done in the 40's. Many times I've found no ground wire. The circuitry seems snakey; one breaker accounts for multiple rooms.
Naturally, where I'm working is downstream of those original circuits. It goes thru a few boxes upstairs before dropping down to this room. It goes to a switch and then to 3 outlets. From there I believe it joined up with another but I can't confirm where that last wire goes. I hope that helps, let me know if I can be more specific.
I finally got my analog reader and here are the readings:

H1 - N1 = 0
H1 - H2 = 0
H1 - N2 = 2v
H1 - G = 0

N1 - G =0
N1 - N2 = 0

N2 - G = 27v

H2 - G = 45v

H2 - N2 = 120v

What's going on here?
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Maybe the problem isn't in that JB?

I assume that H1 and N1 are the Black and White wires of one cable, and that H2 and N2 are are the Black and White from the second cable? If that's the case, then H2 and N2 are the feed into this box. Both blacks nutted together, and both whites nutted together?
Looks like H2 N2 are the feed.
Also looks like you have an open ground.
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