8’ incandescent dimmed when switch is off

[Clint623]

I was deleting the ballast and installing LEDs in 8’ shop fixtures (2 lamp). Before I worked on the first fixture, I noticed that the incandescent lamps were dim on one side and the other was off with the switch off. I went ahead and opened the fixture and tested for hot wires and came across the neutral having voltage. First thought was a shared neutral or grounding issue. After completing the install of the LEDs, I turned off the switch again and half of the LED was on, on each side because of the neutral. What are y’all’s thoughts and solutions?

 

[retirede]

What does “neutral having voltage” mean? What did you measure to? You need to measure L-N with a load.

 

[Clint623]

What does “neutral having voltage” mean? What did you measure to? You need to measure L-N with a load.

I put my fluke widow maker up there and it started going off specifically on the neutral when I had the wires pulled out. Did not measure with a meter to see how much.


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[Little Bill]

I would never trust a non-contact tester alone to verify anything. You should use a meter and check for voltage, preferably a "wiggy" or solenoid tester.
Sounds like some neutrals are crossed somewhere and the return is backfeeding the lights with partial voltage.

 

[retirede]

I put my fluke widow maker up there and it started going off specifically on the neutral when I had the wires pulled out. Did not measure with a meter to see how much.


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Sounds like a compromised neutral. Time to get the meter out.

 

[Clint623]

It’s only happening in this one room.


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[Little Bill]

It’s only happening in this one room.


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It doesn't have to be more than one room. It's likely that a neutral from another circuit with a load on is tied into the light circuit in question and is backfeeding the lights. Doesn't take much to power up an LED dimly. Even a fluorescent in some cases.

 

[Clint623]

Upon further investigation I have nothing to show. I ran a piece of 12/2 from the panel to the lights so I could dedicate the neutral and it had no affect. Since the ground was right there, I checked the old neutral to ground and from hot to the new and old neutral and everything was nominally correct with the voltage and no voltage on the neutral was present. When I disconnect the neutral, the lights turn off like they’re supposed to. So, now that I’ve checked all I can up to this point, I believe it is an internal leak from the old ballast but that doesn’t make a whole lot of sense either.

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[Amps]

What incandescent lamps?

 

[Clint623]

What incandescent lamps?

I meant fluorescent and it wouldn’t let me edit it.


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[Amps]

Could it be a mis-wired switch loop with the neutral being switched instead of the hot?

 

[Clint623]

It’s the old ballasts. I separated the one fixture that I had prepared for LED from the rest of the lights and it turns all the way off where as before half of the LEDs would come on. So, I’m going to change out the other three and roll on.


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[Clint623]

This is what it was doing when the switch was off and connected to the rest of the lights with the old ballast.


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[Little Bill]

By any chance, did the lights have emergency ballasts in them?

 

[Clint623]

By any chance, did the lights have emergency ballasts in them?

No, none of them had emergency e:


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[ptonsparky]

We seldom, if ever, used the old ballasts when installing LED retrofits. Waste of time to leave in another point of failure.

 

[Clint623]

We seldom, if ever, used the old ballasts when installing LED retrofits. Waste of time to leave in another point of failure.

I don’t either but normally I’m able to do one light and turn it on to make sure everything is kosher. When I saw what was happening, I needed to figure out why instead of doing the rest and get in a bind with them not working because they use this space as an office daily..


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[d0nut]

Just replace the whole thing with an actual LED luminaire. At this point you have probably spent more time and money trying to get the existing lights to work than if you would have just replaced them from the start.

 

[Clint623]

Just replace the whole thing with an actual LED luminaire. At this point you have probably spent more time and money trying to get the existing lights to work than if you would have just replaced them from the start.

True


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