New fixture won't turn off.

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Old 03-29-14, 11:48 AM
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New fixture won't turn off.

Hello all and thank you for taking the time to look at my question.

I have recently replaced two wall sconces. When I turn the power back on, Sconce A can be operated with the switch, but Sconce B is permanently on. The wiring is old bx cable I believe.

I've attached a few photos of the wiring, but a brief description:
Sconce A has three black wires connected to each other, none of which are connected to the fixture, three white wires connected to the black wire of the fixture, and one white wire connected to the white wire of the fixture.
Sconce B has two black wires connected to the black wire of the fixture and two white wires connected to the white wire of the fixture.
This wiring is identical to the wiring of the previous fixtures (which had the same problem, except existing Fixture B had a switch on the fixture to control it.
Also, if it is helpful, the end of this wiring run is an outlet after Fixture B, which has constant power just like Fixture B.

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Old 03-29-14, 12:09 PM
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Sconce A ...three white wires connected to the black wire of the fixture, and one white wire connected to the white wire of the fixture.
White wires are never connected to the black wire of the fixture. Are you sure they are white? Are you sure this was the way it was connected.

This wiring is identical to the wiring of the previous fixtures (which had the same problem
So we can't assume any connection is correct. You are going to need a multimeter, preferably analog, to unscramble this. You will make a record of the connections and disconnect all wires including the ones at the switch and the receptacle.. Use the AC voltage setting to determine which cable is 120 volts. Use the ohm setting to determine where the cables go. To do this with the breaker off pick a cable other then hot, connect a switch between the black and white of that cable. Turn the switch on check the remaining cables till you find the one with continuity. Verify by turning the switch off. The cable should now show open. Mark each end of the cable with the same number. For future reference here assign a letter to each box. Example of how to describe the connections: Cable 1 runs between sconce B and receptacle D.
 
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Old 03-29-14, 12:16 PM
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Welcome to the forums!

The color of the wires doesn't matter as much as how they're connected. To troubleshoot this, you'll need to find out where the unswitched power from your panel comes into this lighting system. It may be at the switch or it may be in one of the sconce boxes. With the power off, uncover the switch, pull it out far enough to see all of the wires in the box, and describe what you see.

You are likely to need a meter to test for power or continuity. If you don't have one, you can buy an analog meter for less than $10.
 

Last edited by Nashkat1; 03-30-14 at 04:05 PM.
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Old 03-29-14, 03:26 PM
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Thank you for the responses!
I am sure that this is the way it was connected but I am not positive of the color. They are old wires so the white may look black. But the existing fixtures had the same problem.
When I pull the switch out I see a single white wire and single black wire connected to the two screws in the switch. They both enter the box in the same bx cable. No other wires.
I will plan to pick up an analog meter to do the tests you described.
 
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Old 03-29-14, 03:32 PM
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That means you have a switch loop. The splice with the one white spliced to the blacks is a constant hot.
 
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Old 03-29-14, 05:24 PM
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Important: Before doing ohms (resistance) or continuity measurements, turn off the power. Then for each test be sure at least one of the places you touch the meter probes to is completely unhooked.

If you see several white wires in uncanny locations then it is possible that the switch is in the neutral side of the circuit. The light can still work but various wires and terminals about the light will test live when the switch is flipped off when they should test dead. This is contrary to today's electric code.
 
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Old 03-30-14, 04:29 PM
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When I pull the switch out I see a single white wire and single black wire connected to the two screws in the switch. They both enter the box in the same bx cable. No other wires.
That means, as pcboss said, that the switch is wired as a switch loop. If one of the splices in box A is, in fact, a splice of three black wires, and you have a single white wire that was connected to the fixture, that implies several things:
  • The switch loop appears to be wired backwards (the power should be taken to the switch on the white wire and returned on the black;

  • The power from the panel enters the system at one of the fixture boxes;

  • Box A may be that box;

  • If so, and if there is only a 2-wire cable between the two fixture boxes and the second cable in box B needed to carry constant power to a receptacle, one more conductor between the two fixture boxes is likely to be needed to allow both fixtures to be controlled by the switch.
There's more, but let's just go with that for now. Can you do two more things?
  1. Pull the receptacle and see if it's the end of the run. IOW, are there just two wires in one cable entering that box?

  2. Double check the wiring in box A; there should be an equal number of black wires and white wires there and you've described three blacks and four whites.
 
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