# LED Lighting.



## kb1jb1 (Nov 11, 2017)

If anybody is upfitting with LED lights and has to mark the panel, do it before you start changing out the lights. Recently I have been replacing old lights in a small school, about 200 flat panels. Of course nothing is marked so I clip on the current tracer and start one at a time. By the time I got half way done, there was so much noise on the panel that my tracer did not work. Turn off the lights and the noise stops. Anybody have a suggestion? I can't flip breakers on - off because of the computers. What happens when I can't turn off the lights and need to trace out a receptacle?


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## Almost Retired (Sep 14, 2021)

kb1jb1 said:


> If anybody is upfitting with LED lights and has to mark the panel, do it before you start changing out the lights. Recently I have been replacing old lights in a small school, about 200 flat panels. Of course nothing is marked so I clip on the current tracer and start one at a time. By the time I got half way done, there was so much noise on the panel that my tracer did not work. Turn off the lights and the noise stops. Anybody have a suggestion? I can't flip breakers on - off because of the computers. What happens when I can't turn off the lights and need to trace out a receptacle?


sounds like an after hours labeling job to me
make them turn every pc off before they leave for the day


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## SWDweller (Dec 9, 2020)

Taking a stab in the dark, 
What is the harmonic content of the fixtures? Should be stated somewhere.
Put your Fluke 87 ( or similar) on the feeders in the panel and measure Hz. What is the highest number? Should be in multiplies of 3 180,300, 420,540.
Those are the 3,5,7 and 9 harmonic. Sadly this down and dirty method only tells you that you need a better tool for further research.

What is reading for the ground for the service. Are all the metallic piping systems bonded?

Sure hope they picked the fixtures.


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## MHElectric (Oct 14, 2011)

Those jobs we usually did at night.

School is out right now, why can’t you flip the breakers?


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## dspiffy (Nov 25, 2013)

Cheap LEDs are noisy. In my experience, with better ones, you dont have this issue. It's the cheap switching power supplies.


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## kb1jb1 (Nov 11, 2017)

dspiffy said:


> Cheap LEDs are noisy. In my experience, with better ones, you dont have this issue. It's the cheap switching power supplies.


I 100% agreee.


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## frankendodge (Oct 25, 2019)

You might be able to figure it out with an amprobe, a helper and a phone. I've had luck with that. 
Clamp around all the hots or a few sets in a conduit at once to narrow it down, have them call out as they switch the light off and on. Can you safely add a temporary load to the circuit you are searching for? I use our heat gun.
Otherwise, probably an off hours labeling mission.. Find out what breakers are running their critical stuff, computers etc too.. Unlabeled panels, I picture scary wiring with who knows what wired to who knows where.


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## CADPoint (Jul 5, 2007)

I've used this before but outright pricey 

Tasco CMT24DS - Circuit Mapper System; 24 Circuit Panel 
https://www.tequipment.net/Tasco/CMT24DS/Wire-Tracers/

If 48 circuits just use #1 lead on 25th circuit, etc. One just has to pay attention.

I think I'd at least ask for a drawing layout from facilities dept, most have them in 
CAD or a copy of something...


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