Old wiring in an old house
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I'm assuming you have 2 wires coming in and out of a light fixture box?
Should be 1 hot and 1 neutral.
You need to switch the HOT conductor, not the neutral conductor.
The neurtal stays connected to the light, the hot wire coming into the box connects to the black wire going to the new switch. At the switch, the black wire connects to one screw on the switch, and the white to the other screw. THE WHITE MUST BE RE-IDENTIFIED AS A HOT CONDUCTOR. This is done by wrapping black electrical tape around the white wire in at least one place, the tape must completely encircle the wire. At the light fixture, you attach the white wire from the switch to the old hot terminal on the fixture. The white wire MUST be identified as a hot here also.
If you are not comfortable doing this, or identifying the hot conductor, you really should have an electrician hook it up for you, especially in a bathroom where things get wet.
Should be 1 hot and 1 neutral.
You need to switch the HOT conductor, not the neutral conductor.
The neurtal stays connected to the light, the hot wire coming into the box connects to the black wire going to the new switch. At the switch, the black wire connects to one screw on the switch, and the white to the other screw. THE WHITE MUST BE RE-IDENTIFIED AS A HOT CONDUCTOR. This is done by wrapping black electrical tape around the white wire in at least one place, the tape must completely encircle the wire. At the light fixture, you attach the white wire from the switch to the old hot terminal on the fixture. The white wire MUST be identified as a hot here also.
If you are not comfortable doing this, or identifying the hot conductor, you really should have an electrician hook it up for you, especially in a bathroom where things get wet.
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The info posted could not be more wrong.
Please hold in there for a real electrition to post the right ansewer.
Please hold in there for a real electrition to post the right ansewer.
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4,352 Posts
I'm not fully understanding why you ran a new wire, is it to feed another switch, or simply another light using the existing switch?
Either way, it sounds to me like you either have knob and tube wiring or a switch loop. Either way, you will not be able to extend this wiring to feed something else.
Edit...You need to be more specific with what you are trying to do and what is already existing.
Either way, it sounds to me like you either have knob and tube wiring or a switch loop. Either way, you will not be able to extend this wiring to feed something else.
Edit...You need to be more specific with what you are trying to do and what is already existing.
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OK, the white wire going from the lighting fixture should be connected to the HOT (not the black wire), and the black wire coming back from the switch should be connected to the fixture.
I did have that wrong, code reference below:
200.7 (C) (1)
Exception (1)
If part of a cable assembly that has the insulation permanently reindentified to indicate its use as an ungrounded conductor by marking tape, painting, or other effective means at its termination and at each location where the conductor is visible and accessible. Identification shall encircle the insulation and shall be a color other than white, gray, or green. If used for single-pole, 3-way, or 4-way switch loops, the reidentified conductor with white or gray insulation or three continuous white stripes shall be used only for the supply to the switch, but not as a return conductor from the switch to the outlet.
I did have that wrong, code reference below:
200.7 (C) (1)
Exception (1)
If part of a cable assembly that has the insulation permanently reindentified to indicate its use as an ungrounded conductor by marking tape, painting, or other effective means at its termination and at each location where the conductor is visible and accessible. Identification shall encircle the insulation and shall be a color other than white, gray, or green. If used for single-pole, 3-way, or 4-way switch loops, the reidentified conductor with white or gray insulation or three continuous white stripes shall be used only for the supply to the switch, but not as a return conductor from the switch to the outlet.
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Knob and tube is my vote.
There was a light with only a pull chain switch. I am trying to install a wall switch. There is only one single wire coming in the box and one single wire going out of the box. I am comfortable with most wiring but not this situation. Thank you for your response.
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So, you have an unswitched light (has a pull chain but that's fixture mounted) on a box with 2 wires in it. One wire will be hot, the other neutral. You would put a switch loop on the hot leg in that box and make sure to relabel the white wire as mentioned because it becomes a hot wire.
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Yes, I understand. In newer wiring, one of those wires would be colored black (hot), and one would be colored white (neutral).
Both of yours are black but one of them is a hot and the other one is a neutral.
The next thing to do is to determine which one is which. You can do this with a meter, or a simple electrical tester.
Do you have a tester?
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