Switching the Neutral?

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Old 11-23-20, 08:13 PM
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Switching the Neutral?

Found at a property...the occupant, or his relative, removed a ceiling light, and failed to get a reinstalled one working. I found power in the ceiling box going down to a switch leg on the wall. Everything seemed wired correctly, but it still didn't work.

Out of curiosity, because they were old wires and difficult to identify, I looked to see if they were switching the hot by checking the wires to a known ground. I found that they were switching the neutral instead of the hot, corrected it and now it works.

But here's the thing, as I've drawn what's pictured, and I know not to switch the neutral....still I am curious why the light didn't work switching the neutral anyway?

 
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Old 11-23-20, 08:17 PM
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It should not have made any difference switching the white or black.
Black/hot is typically switched so that when the switch is off.... the light is dead and safe to work on.
 
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Old 11-23-20, 08:20 PM
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If you wired up a light and mistakenly put the switch in the neutral instead of the hot then the light will still work.

What you drew should have worked.

Since in your case the light did not work, there was something wrong elsewhere in the circuit, which actual circuit was really not the same as what you drew..
 
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Old 11-23-20, 08:23 PM
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I understand what you're saying...but somehow, switching the neutral = light dead. Switching the hot = light works.

One more weird qualification, the wrongly switched neutral made analog meter read 118v when switched. BUT the SAME 118v would not light a 60w bulb??? WTF

There is no ground if that means anything...the wiring is too old.
 
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Old 11-23-20, 08:28 PM
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It may have been a loose connection. The circuit will work switching the hot or the neutral.
 
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Old 11-24-20, 05:25 AM
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What two places were the meter probes touched to when you read the 118 volts?

1. With the switch in the neutral path and flipped on?

2. With the switch in the hot path and flipped on?
 
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Old 11-24-20, 10:45 AM
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Another idea: how old is the wiring you're working on? Back in the days of knob & tube wiring, not only would they sometimes switch neutrals, but they would do wacky things with 3-way switches too. So that diagram you drew and think you're working with could be something different behind the walls.
 
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Old 11-24-20, 06:45 PM
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I think it's 1940's wire, no K & T wiring, with a later version of 14-3 romex added to it, as in the pic attached.

To answer Allan J....
In each case of questions 1 and 2 the meter probes were on the ceiling box wires feeding the light.

--The pic shows how it was wired and worked, once I identified the correct hot wire...
--The dysfunctional before version trying to switch the neutral is basically the same pic, except the power wires B & W are swapped, and MAYBE I used the black and white of the 14-3 for the switch leg.

Now...while we're on the before version...backing up...when switching the neutral, I Got 118v across the ceiling box wires, and that should have fired the light, but DID NOT. I physically put the LED bulb base contacts right on that 118 volts and it WOULD NOT LIGHT!

The bulb is good and it's not a low voltage bulb. Someone else suggested that the little load of the bulb made a bad connection open up....? Still somethings don't add up nonetheless.
 

Last edited by PJmax; 11-24-20 at 06:53 PM. Reason: reoriented/resized pic
 

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