Very Old Houise...apparently screwed up wiring

[H_X]

I am working on my son's 100+ year old house, and someone put in a gas furnace. It works fine.

I am helping him install a new large closet, but when we went to move an old lighting fixture out of the way, we cam across a bunch of wires in a box above it. The thing about the wire, is that within the bundle of white wires, one of the white wires was hot. Again, this was connected to all the other white wires in the box.

I was suspicious of that wire, so we left it out of the group of other white wires.

We later on noticed that the furnace was not working.

Shaking my head, I reattached the "hot white" to the other white...and the furnace went on.

It gets wierder from here.

I am assuming that a qualified electrician wired the house, and made the black wires hot. There appears to be some evidence of that. Nevertheless, I am hooking up a socket, and when I did it did not work. In fact, the White wire is hot on that circuit too. I suspect the white wire I put back into the mass of wires has electrified the entire house's white.

Any ideas what the heck is going on?

Thanks. H

[RBM]

It sounds like you removed a neutral conductor from a pack of neutral wires. If there is a load on that circuit, it will appear that that isolated wire is hot, when it is a return in search of it's neutral

[hrhofmann]

You'll have to start back at the fuse box and trace everything from there. To do otherwise could cause a fatal event sometime in the future, plus when you go to sell the house it will be impossible to do with the wiring the way that it is.

[dpb]

hr(bob) [e-mail] wrote: ...

Neither at all likely; second essentially impossible.

I'd wager high odds RBM has first instance correct; possibly the same symptom in the second although at a light it's possible he simply has the switch leg that somebody didn't mark.

If it's been functioning, it's likely the overall wiring is not grossly at fault.

To OP, one would presume there was an inspection before the son bought the place???

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[H_X]

There was an inspection. I do not recall any mention of the wiring, however.

It appears that the wires atop the light fixture (and there are a lot of wires) are there because the original wirer was using that box for a central wiring point ( I think there are 6 wires connected togther).

Nevertheless, why would a switch-leg be hooked up to the neutral wires?

[dpb]

H_X wrote: ...

Are you absolutely sure it's a neutral, not just the switched leg being a white conductor that wasn't marked at the end? That would be my first presumption and is relatively common w/ 2-wire romex on occasion.

An inspection certainly _should_ have covered basic electrical and even the most rudimentary typically check wiring for correct neutral in outlets, continuous grounds, etc. One would presume if such were found they would have been noted.

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[clare]

The white wire is "hot" if the furnace is turned on. ALL white wires are "HOT" when there is a load on the circuit and the white wire is "open". Just take a look at a circuit. We'll look at it as a DC circuit for clarity, but AC is the same.

Power comes out of the fuse box on the black wire - it is "Hot". That black wire goes to a switch. When the switch is off, the second wire is "cold", when it is on, it is "hot". The black wire continues to the load - let's say a light. The power flows through the light - so both sides of the light are "hot" but the light is not on. The white wire connects to the light and returns to the neutral busss in the fuse box. If that neutral is "lifted" anywhere wetween the lamp and the buss, it is "hot".

[John Grabowski]

*It could be as RBM suggested, but unfortunately with that old of a house anything is possible. In a situation like that it may be best to just install new wiring at least to the furnace. To fully understand what is going on one would need to identify each conductor in the box and its function. One pair is the feed and another pair apparently feeds the furnace. Now figure what the others are doing. If there is a wall switch then one pair goes there.

[Steve Barker]

seems normal to me. white wires carry current also. takes one of each to make a circuit.

sounds like you need to leave things alone.

[Van Chocstraw]

Old house wiring is scary. Most have a single circuit for every room in the house, lights and outlets. In the old ice box days where all they had was a light in a room it was fine. No good today. Rewire the house starting with a new panel.

[trader4]

Good question. Answer: it wouldn't. And if it was, the breaker would trip. I agree with RBM. Given that you seperated one neutral from the others and the furnace no longer runs, it appears you have disconnected the furnace neutral from where it was connected to other neutrals and hence it;s connection back to the panel. A neutral is there to complete the circuit and carry the return current. If you open a neutral that has an active load on it anywhere along it's path the neutral will then appear hot. That is, if you measure between it and neutral or ground, you will see 120V. If you touch it back to the other neutrals where it belongs, you'll also see a spark, assuming the load is big enough.

[Don Young]

If the house is wired with conventional white neutrals and black hots it is possible that they are reversed at the panel or someplace in between. If the panel lacks a ground, they could even be reversed at the meter or drop. You actually need to test to a known good ground to be able to tell whether a wire is a neutral or a hot.

As others have mentioned, a disconnected neutral with a load connected will be hot. I really do not read anything in your post that indicates a problem.

Don Young

[clare]

If it WAS it would not be connected to a lot of other whites, and would not have shut off the furnace when disconnected. It is as it should be - if the furnace was turned on (not even calling for heat) the neutral WOULD be "hot" when lifted. Has to be. No other way around it.

[clare]

The OP did not mention Knob&Tube, and DID mention a "BOX" so the wiring is likely circa 1950 or newer. Remove fuses/shut off breakers untill the furnace is shut off. Does anything else not work? To meet code, the furnace MUST be on it's own circuit. If it is, don't worry about it. If not, get a good electrician in to check it out and let you know what you have. Hint - get a BUSY electrician so he's not out REALLY looking for work!!

[Doug Miller]

Cite, please.

[JIMMIE]

Its not weird at all, An open neutral measured to ground or another neutral will read hot if the other side of the load is hot. What you see is not an indication that anything is wrong. By taking it loose to measure it you have floated it above ground so now it is connected to the hot side through whatever load was feeding.

Jimmie

[Joe]

422.12 Central heating equipment....shall be supplied by an individual branch circuit.

Joe

[dpb]

[e-mail] wrote: ...

_IF_ that is indeed the same white--wasn't clear at all to me and was assuming it was different. But, maybe it was, who knows for absolute certain...

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[JIMMIE]

Could be like my furnace was wired. The main power going to the motor was on on an individual circuit but the control voltage transformer was connected to a light circuit in the attic. At one time this may have been OK. When my new heat pump was installed they had to by code install attic lighting and an outlet near the HVAC unit in the attic the new transformer was tied into ths new circuit. The old transformer was tied into the bathroom lights. When I asked the electrician who wired in the new HVAC unit about this he said it should have been connected to the outlet circuit but otherwise it was no big deal. At least it wsa labeled in the panel box as furnace/ Broom lts .

Jimmie

[RBM]

422.12 Central heating equipment....shall be supplied by an individual branch circuit.

Joe

While that's code today, I don't believe that it was code back a while. One of the things I do a lot of, is boiler wiring, and It seem rare when a house built in the forties or fifties, has the boiler on a dedicated circuit