Crossed wires? (long)


Old 12-25-00, 02:52 PM
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Hi, I just moved to this apartment and found a very confusing problem:
The living room light doesnt work and I can't find a switch for it.
By the entrance door there is a 4X4 box with one switch to control the outside stairs light which in turn has another switch downstairs so you can switch on the stairs light at the entrance door then switch it off once inside the house.
In the 4X4 box there is room for another switch, which I assume is where the living room switch used to be.
Here is What's in the box.

1) Left punch out, which points toward the outside light: Romex with blk/wht wires, blk to large wire nut (for reference nut 1) and white to small nut (a)

2) Bottom p/out: Two romexes, three wires each. Left one: White wire go to nut 1 and blk/rd both go to large wire nut (for reference nut 2).

3) Bottom p/out, right romex: blk to nut 2, red to left side bottom of switch, white to left side top of sw.

4) Top p/out romex with blk/wht wires, wht to nut 1 and black to right side of sw.

5) There's a blk wire coming from nut 1 with a small nut at the other end (b)

6) a to gnd is 0v b to gnd is 120v

I assumed that nuts a and b were the lamp switch wires, so I measured the voltage with lightbulbs in the lamp, and got 120v. Then I took the l/bulbs out expecting to get zero v, instead I get 99 volts(??).

Any input would be apreciated.

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Old 12-25-00, 04:07 PM
Join Date: Dec 1999
Location: Northeastern NC On The Albemarle Sound
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It's your landlord's problem.
Call them to replace your living room light switch.
Not necessary for you to even get involved in the elctrical side of it.
Good Luck!
Old 12-25-00, 07:14 PM
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Well the landlord is fixing it, but that doesnt teach me anything.
Old 12-25-00, 08:38 PM
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Your description was exceptionally clear. I commend you.

However, your wiring is quite strange, so it is almost impossible to speculate on the purpose of all the wires without more diagnosis. The color coding of the wires is particulary mysterious. I'd like to help with your education, but you seem to have a particularly poor example to learn from.

Want to pursue this further anyway? Here are some things to do:
(1) Turn off the power. Temporarily disconnect all wires from the switch and from each other. Turn the power back on. Measure all voltages to ground. Then flip the 3-way switch downstairs. Repeat all voltage measurements. The wire that is hot in all tests is your line hot. It could be that none of the wires in this box are line hot (but I think that unlikely, since you have so many wires).
(2) Now try to find your line neutral. With all the wires still disconnected, measure voltage between your line hot and all the other wires (excluding the grounding wires). The one that measures voltage identifies your line neutral.
(3) Now turn off power again. With the wires still disconnected (and good light bulbs in all the fixtures), use your ohmmeter to find continuity. Remove the light bulbs and if continuity goes away, then you know which wires connect to which lights.

Report back and we'll go on to lesson two.
Old 12-27-00, 03:48 PM
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Hi, thank you for your response. I decided to hire an electrician due to my lack of time to pursue this on my own (I've working late lately).

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