Question About Old (+/- 75 Years) Ceiling Box Wiring

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Old 04-24-17, 07:10 PM
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Question About Old (+/- 75 Years) Ceiling Box Wiring

Hi, i just replaced a 1940-or-so bedroom ceiling fixture with a westinghouse ceiling fan brace. It was not a painless experience.

Anyhoo, now I want to hook up the new ceiling fan. But the wiring I encountered seems wrong. Cable is steel armor, two-wire cloth wrapped.

3 flex conduits

1 wirenut with 1 wire from each conduit
1 wirenut with 1 wire from each of two conduits, plus a BLACK wire to the old light
the 1 remaining wire connected to WHITE wire from the old light

The old wires are mostly too frayed to tell if they were labeled black or white. So I can't tell. I did cut back one of the conduits (i had to; the wire broke), and the cloth, when I unwrapped the crumbling paper wrap, looked for all the world to be white. THIS WAS ODD, BECAUSE it was one of the two wires that were wired to the BLACK wire of the old fixture.

It seems to me that if that wire were white, it would have been connected to another white wire, plus the white fixture wire.

So I'm wondering if whoever installed the fixture wired it wrong. And how can I discern this? I have the use of a Mastech MS8232B but I'm not, um, adept with it. Also, as it stands the 6 wires in the box are in very close proximity to each other...

Any and all assistance appreciated.
 
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Old 04-24-17, 08:40 PM
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Check and see how many wires are in the switch box. You might have a switch loop.
 
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Old 04-24-17, 09:45 PM
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Not related to your posted problem but it is unlikely that the existing ceiling box is fan rated. If not it should be replaced for safety reasons.
 
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Old 04-25-17, 10:11 AM
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Thanks, Boss & Ray,

I did install a ceiling fan rated box. (The one that came with the Westinghouse brace kit.)

There are 2 wires in the switch box. I think it is a switch loop, but I also think whoever installed the ceiling fixture mixed up the leads to the light.

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The three leads (one from each pair) that are taped yellow were wired together. The second wire coming in from the left (as you're looking at the photo) was connected to the white lead from the light fixture, so I taped it white. The second wire coming in from the bottom was connected to the black lead from the light fixture, so I taped it black. That lead was also connected to the second lead coming in from the top (no tape).

The reason that wire has no tape is that it broke off when i was disassembling. So I cut back the armor...and the broken wire looked like it had maybe been white back in the day. But it had been connected to the black-taped lead and to the black wire from the light fixture.

Weird, no? Shouldn't the white-taped wire be connected to the untaped wire, and shouldn't those then be connected to the white wire from the new fan I want to put in?

Or am I missing something...? Can I check any of this with my multimeter or with some other nifty device?

Also, any hints when it comes to twisting these old, brittle wires back together?
 

Last edited by t_finx; 04-25-17 at 10:15 AM. Reason: the photo uploaded sideways so i had to rewrite...
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Old 04-25-17, 12:08 PM
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There are 2 wires in the switch box. I think it is a switch loop,
That is most likely. Disconnect the wires. One cable should show ~120 volts between the two wires. That is your power in. The other cable should be dead. That is the cable to the switch.
  • Black of power in to white of switch cable.
  • Black of switch cable and white of power in to fan.

To determine which wire is hot use an extension cord plugged into a correctly wired receptacle. With your multimeter measure from the wide slot of the extension cord to each (disconnected) wire of power in. The one that shows ~120v is your hot. You may also be able to do this by measuring to the jacket of the metal cable or box.

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Old 04-25-17, 01:23 PM
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Also, any hints when it comes to twisting these old, brittle wires back together?
Be gentle! But if the wires cannot withstand even careful manipulation, then it is no longer serviceable and really should be replaced. Sometimes you can do a reasonable repair by sleeving damaged sections with heat shrink tubing which is easier to apply than tape in a tight box. Ultimately however if you have brittle wires that are effectively uninsulated it is a safety hazard. Ceiling boxes are especially vulnerable because of all the years of over heating from the light bulbs. Often the old insulation has literally turned to dust.
 
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Old 04-25-17, 02:46 PM
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Allrighty!Thanks again -- much appreciated!
 
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Old 04-27-17, 11:03 AM
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ok, I'm an idiot.

There are two wall switches in the room. Both are simple 2-wire switches.

As far as I knew, the two switches were separate when I started. They each control one ceiling fixture in the room. (I hardly think about the second switch/fixture, because it's in a small alcove and I never use it.)

So I connected the fan the way I thought it ought to go and turned the power back on... and the fan is now connected to the second wall switch, which now controls both its old light and the new fixture. Where did I go wrong?

As I said in my original post, when I started, there was a black wire connected to a white wire in the box, and those were connected to the white wire on the old fixture.

Now I've got two white wires in the box connected to the white wire in the new fan, and the black wire connected to one black wire in the box.
 
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