For the Electrical Wizards....


Awl --
So I finally unloaded those 20 old #14 bx cables off the ancient upstairs fuse panel, onto a breaker panel downstairs, 7 (mis-wired) Edison circuits and all....
It went pretty well, with about half the bx cables able to reach the new panel, and half being spliced upstairs, via #14 wire in 3/4" Greenfield.
The advice here prior to the job proved invaluable, and **many thanks to all who offered their thoughts and hard-earned knowledge and experiences**. ahr is really a web-treasure.
But.... Holy shit, What a job!!!!. You might wonder, Well, what's so tough about DAT? I don't really know, as much of it is a bad fog now.
But, I can say that including the demolition (about 70 sq ft of heavy plaster/lathe wall, about 30 feet of 10" duct in about a 1.5' x 1.5' wood encasement), this was a 3-week job, many days 10 and 12 hours days. Admittedly some head-scratching time, but mostly back-breaking and finger-wearing labor. Including some moved appliances, gas plumbing.
What a I thought would be an afternoon's work would turn into days.... Good thing I'm not in the contracting/estimating business, dats f'sure.... And the cosmetic finishing still awaits, an even longer job. But everything is at least functional now.
But here's some weird/funny stuff I encountered.
1. During the demo, I inadvertently cut a bx cable, an edison circuit. Would normally not be a problem, except the "red" had so faded that it is sort of indistinguishable from the white, ie, both appear tan/beige. Worse, I don't really know what these wires control, as the house was wired in a helter-skelter fashion, where one fuse would control a hodge-podge of outlets/lites.
How do I sleuth this out? It seems to me, for the time being, it would be best to keep both presumed hots on the same leg for now. Nothing is blowing so far.
2. While unloading the fuse panel of its neutrals (first I'd remove the hot from the fuse, then the corresponding neutral), my main temporary neutral connection to one fuse panel became undone, unbeknownst to me.
As I unloaded the circuit neutral (hot already removed), there was still arcing. I'm assuming that with the main neutral removed, this neutral was carrying return current from *other* hots, with the current eventually making its way to ground (btw, these bx cables don't have a ground wire). Ergo, arcing from other hots?
Is this to be expected, with a main neutral removed?
3. With a non-edison circuit (one hot/neutral) controlling a few lites/outlets in the kitchen, and all wires separated in a junction box from a demo'd wall, I noticed on separating out the old mess that I could get an outlet and lite to go in series, ie, both would dim.
I can readily see how this would happen in an edison circuit with a lifted neutral (in which both lites etc would be normal OR one dim and the other too brite), but I haven't been able to sketch out how, with just one hot, parts of the circuit would wind up being in series.
Is this normal with a lifted local neutral? Or does this indicate a fundamental wiring problem? How to sleuth?
tia.
--
EA



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wrote:

You say you have an edison circuit, ie shared neutral and cut the cable running from the panel. Now you propose to put both hots on the same leg, exactly why, I'm not sure.
This is an example of why I'm not a big fan of shared neutrals. It's very easy for someone doing repair work who isn't familiar with these to create a dangerous situation. If you do put both hots on the same leg, you will now have a maximum current on the neutral that is twice what it was previously, ie it will be equal to the sum of the two breaker currents. I doubt the conductors are rated for that.
The rest of the stuff below is too confusing to even attempt to comment on, except that if you are working on circuits that are de- energized correctly PRIOR to beginning work, there shouldn't be arcing going on while you are working on them
Given the above, I'd be concerned about safety of not only doing the work, but also the finished product.

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wrote:

You say you have an edison circuit, ie shared neutral and cut the cable running from the panel. Now you propose to put both hots on the same leg, exactly why, I'm not sure.
This is an example of why I'm not a big fan of shared neutrals. It's very easy for someone doing repair work who isn't familiar with these to create a dangerous situation. If you do put both hots on the same leg, you will now have a maximum current on the neutral that is twice what it was previously, ie it will be equal to the sum of the two breaker currents. I doubt the conductors are rated for that.
The rest of the stuff below is too confusing to even attempt to comment on, except that if you are working on circuits that are de- energized correctly PRIOR to beginning work, there shouldn't be arcing going on while you are working on them
Given the above, I'd be concerned about safety of not only doing the work, but also the finished product. ================================================= Dude,
I was suggesting putting the two hots of the cut edison (or what I *think* are the hots) on one leg just as a precautionary/sleuthing technique, so at least if I botch something circuit-wise, it'll be a 120 botch, not a 240 V botch. There was an extensive thread on edisons.
There were seven original edison circuits, and every one of them had both hots on the same leg in the original fuse box. So the situation now is VASTLY improved. And, any added new circuits I add will certainly not be edisons.
My Q basically was: if you *know* you have an edison, but are not sure of what's hot and what's neutral, how do you tell? In old 1920's wiring, where grounds are not so good or uniform.
My main query after that was, given a branched circuit off just one hot wire (no edison), how is it that various outlets and lights wind up in series, with a lifted local neutral? And, is this normal?
The other query was the behavior of circuits with a lifted *main* neutral, but I guess odd things are to be expected in that case.
--
EA



>
> 2. While unloading the fuse panel of its neutrals (first I\'d remove the
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wrote:

Dude, if you really understood what an edison circuit was, you'd know that if it was in fact wired this way, then what you had were NOT edison circuits. And if they were wired the way you describe, unless the neutral was of sufficient gauge to have twice the current carrying capacity of the two hot conductors, you had a serious fire hazard. In the wiring you describe that neutral is carrying a max current equal to that of both hots. So, let's say you had two 20 amp breakers and all the conductors were 12 gauge. Now you have a potential current of 40 amps flowing in a 12 gauge neutral wire.

It's not at all clear to me how anything is vastly improved

I don't see what determining hot from neutral has to do with the presence or absence of uniform grounds. And sorry if this offends you, but I'd say if you have an edison circuit and you can't figure out how to tell how from neutral it's time to call in an electrician, because if you can't do that, you shouldn't be screwing around with it.

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Existential Angst wrote:

When all the other electric is reconnected find what is not powered. If everything is powered I would probably leave the circuits disconnected.
If you find a receptacle, for example, is not powered plug-in a lamp that is turned on. Connect the known hot to power. One of the other wires may light the bulb if connected to the neutral bar. If not the receptacle is probably is on the 2nd hot wire. In that case I might pull the receptacle and if one wire is clearly a neutral check continuity to the wires in the panel.
If you connect wires to power connect them to the same fuse/breaker. (That may be what you did.) That covers trader's concern.

If the hot is disconnected (or both hots for an Edison ckt) there shouldn't be a significant spark when you disconnect the neutral. (There could be a tiny spark from capacitive currents.)

I don't know how you get that with just one hot and the corresponding neutral connected. For an Edison ckt with a lifted neutral, the light and outlet could be on the same hot wire and something else could be getting bright. I assume you fixed the floating neutral bar in #2 before this occurred.
--
bud--

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