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Jason, Service Technician
Category: Electrical
Satisfied Customers: 4286
Experience:  Over 20 years of experience in all types of installations, troubleshooting, and repairs.
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old 2 wire system, house built in 1923, hanging a ceiling fan,

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old 2 wire system, house built in 1923, hanging a ceiling fan, electrical box is working like the neutral wire and completing the circuit, switch works, light goes on and off, will not work when I connect wiring black to black, white to white, what's up
Hello. Are you saying you get a reading (with a meter) of 120 volts from the hot wire to the metal box. Or, when you connect the hot lead of the fan to the black wire, and the white lead from the fan to the box, the fan runs?

Customer: replied 7 years ago.
both, I disconnect and checked the wiring with a volt meter, when I had touched the hot and the neutral there was no reading, when I touched the hot and the box I got 120, I then connected the hot to the light and I connected the neutral from the light to the box and it worked and so did the switch
Thank you for the additional information. The symptoms you describe are indicative of a loose connection. The neutral wire is loose, and the box is somehow grounded. Considering that this is a 2 wire system (no safety ground), the fact that the box is grounded leads me to ask - is this a romex system, or are the wires in flexible or rigid metal conduit?

Since this post contains information that could be construed as an answer (the info about the loose connection), I am required to send it as an answer, which will prompt you to accept. But I prefer you wait until we dig into this a little further.

I will await your reply. Thank you.

Customer: replied 7 years ago.
It is metal, BX? Also, there are other lights on this circuit. Others are working, 2 others are not and are showing the same indications.
Thank you for the additional information. Because the box is connected to BX cable, the box is grounded. That's why the light and fan will work when you touch the neutral wire to the box. As I'm sure you are aware, it would not be good to use the box as a neutral wire.

Have you tried to trace the neutral wire back to the previous box? Is it at the wall switch that controls the ceiling box you are working on? Is there a neutral splice in the wall switch box? If so, how many neutral wires are in that splice?

Customer: replied 7 years ago.
Actually the wiring runs through the ceilings. All the walls are concrete blocking. I am getting and indication from your questions that the problem might be that I may have broken the insulation on the wiring, which is very old and brittle, and that might be making metal contact to one of the boxes?
No, I don't think missing insulation on the neutral wire would cause the problem you are seeing. You have a loose neutral connection somewhere ahead of the ceiling box you are working on. It could be in the light switch box that controls the ceiling box (if there is a neutral splice in the wall switch box), or further upstream. Often, with the old 2 wire BX systems, you will find the splices were soldered, instead of wire nutted. It's not uncommon for the solder to crack after many years of expansion and contraction due to loads being on, then off.

You will need to try to trace the circuit back "upstream" from the ceiling box you are working at. Repairing this will require opening boxes to check for loose neutrals until the problem connection is found. You will likely find the connections taped up, which means the tape will need to be removed in order to conduct a thorough visual inspection of the neutral splices.

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