Contradictory Advice! Can you help?

Old 07-25-03, 01:30 PM
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Contradictory Advice! Can you help?

I need help! I am new homeowner and I confused.

I have been searching these boards for help on my wiring problem. In a previous post regarding someone who said they had only 2 black wires from the ceiling and no other wires, I read:

"regular incandescent light fixtures will work exactly the same if you reverse the wires, and I'm pretty sure you will have no problem hooking it up without regard for which is which."

However, I have also read in another post:

"you should get a voltage tester to figure out which is the the hot and which is the neutral wire before installing a light".

Here is my problem - I have a house built in 1930. I am replacing a celing light. There are two wires from the celing - both are black, with white cloth in the centers with a single copper wire coming from the center of each.

My light is brand new, regular incandescent and has black, white and copper. I can know I hook the copper to the green screw, but DOES it matter which wire I hook to which wire?

Old 07-25-03, 01:42 PM
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Both statements sound correct to me. Typically you would want to hook the black to power and white to neutral, although the fixture will light up if the wires are reversed. If you have a tester, (there are little chirp testers that will beep on a power line) take the black to the wire that is hot (chirping).
Old 07-25-03, 01:48 PM
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Are the two wires seperate, or do they come from the same cable entering the box? Given the house is from 1930, I automatically assume the old-fashioned, and commonly dangerously out-dated knob-and-tube wiring. With knob-and-tube, the wire are supported by ceramic insulators. Romex wasn't available until the late 1930s, and not commonplace until 1940. Do you have a multimeter, or would be interested in buying one for future projects? Option #2 is a "ticker" (size of a magic marker, blinks and beeps when squeezed and within the magnetic field around a "hot" conductor when it is energized.
To use multimeter, go between a wire and the box, I suspect this will be null without grounding in old wiring. There are other ways to test though with a multimeter.The ticker may be the better/inexpensive choice (+ lifesaver tool). Short of a long explantion, it should give a solid responce to the hot wire, and ordinarily no respnce to a neutral.
Important: Do you have circuit breakers, or fuses? If fuses, a fuse panel, or fuse box with ceramic dual fuse holders?
FYI: the reason for having Blk s. WH is the same as polarized plugs/connectors, the screw shell of the lamp is connected to the neutral, to prevent accidenlty having your fingers touch hot to the grounded fixture frame. (ground and nuetral bonded at main panel).

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