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Old Wiring

04:20AM | 07/10/01

Member Since: 05/28/01
5 lifetime posts

Old Wiring

Hi,
I have an old fixture in the Kitchen that needs to be replaced. It's a pull chain light on the old knob and tube system. The fixture and wires are so old they are not color coded. The new fixture has a white and a black wire. How do I know which is the Black wire on the two wires coming from the ceiling? One wire has a piece of black electrical tape attached to it so I assume it was put there to indicate the black wire, but I am not sure. What would happen if you mixed these wires up? Would it not work? Or would it work but have a greater risk of fire? Please help.

Thanks,

Sean

MarkV

10:36AM | 07/23/01

Member Since: 04/05/01
32 lifetime posts

While it might not do any harm to wire it up either way, the preferable method is to wire the hot, or black, wire to the proper lead from the fixture. This ensures that the hot contact of the fixture is the one that is at the far end of the fixture, in the centre, and not the threaded part. The reason for this is that it is much easier to accidentally touch the threaded part than stick something down to the bottom. If the threaded part is hot (electrically), and you touch it, it most certainly would cause harm.

A $10 multi-meter is well worth it.

Good luck,

Mark

Lawrence

04:54PM | 07/27/01

Member Since: 11/14/00
333 lifetime posts

It does not matter much. However, the black tape on the wire is a very common electrician's "code" for "Hot," so your suspicions are correct. Sometimes it can be confused with electrical tape that is there for protection, though, when someone noticed a cut or fray in the insulation.

You can also buy a $10 tester that detects the PRESENCE of electricity. It looks like a marker pen with a plastic tip, and beeps repeatedly if the button is pressed in the presence of "hot" wires. You can hold it up to the two wires and the one that makes the tester beep will be the hot wire that you should connect to the black wire on your light; the other will be the neutral wire that you should connect to the white wire on your fixture. That tester is a very handy thing to have, in general, when working on any sort of electrical project, and has saved me a few times.

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