# Led light problem



## gpop

8 Led light panels (about 4' x 4') installed new about 18 months ago and worked perfect.

Light are 480v single phase via a contactor. 

The connection is via a 17amp 3 pin twist lock plug. Inside the lights there are two 480v to 277v packs. Each 277v pack connects to two power supply's that are rated 277v to 30vdc ( so 4 total in the light). The 30vdc goes to strips of led's.

We shut the lights off for the weekend then on Monday we turn them back on and have had no problems until now.

On Monday the lights get turned on and do not light. Checked voltage at lighting contactor and it has 480 in and 480 out. 

Turn off power and open up first J-box, Nothing looks ugly so we check the wire nuts the turn the power back on. Lights come on.

Turn the power off to put the wires back in the junction box. Turn power back on lights don't work.

Meter says there isn't a problem. rinse and repeat a few times then decide to get the high lift and get to the lights.

power at the receptacle reads 480v leg to leg and 277v leg to ground.

Go for coffee. come back and lights are on.

Turn lights off and on a few times and they work fine.

Turn lights off and put and the covers back on the lighting contactor. Turn them back on and lights do not come on.

Getting frustrated with the randomness of the problem so we replace the first section of wire to the first light in the chain. This counts out all junctions (straight pull no wire nuts), Bypassed the lighting contactor to count that out and turned on the lights, they did not come on.

Went for another coffee come back and every fitting had some strips of lights on.

To me random would be if some lights worked some times but when all 8 act the same its weird.

removed one light and replaced with a standard HPS high bay. High bay works fine (takes 3-4 mins to re-light when switched off and on as expected) Other 7 leds sometimes come on sometimes don't.

Tested removed led panel in the workshop and it worked fine many times then stopped working. Tested with meter and 480 to 277 was fine. 277 to 30vdc tested 0vdc. nothing is reading above ambient temp. Replaced 277 to 30vdc pack with a new one then tested and still 0v on all 4 packs.

Go for coffee to see if they run on coffee. come back and light is on. Turn off and on and its fine.

Once on the lights will work fine all week. 

What am I missing............? (sorry its a long read)


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## TGGT

gpop said:


> What am I missing............?


More coffee. 

Sent from my SM-G930T using Tapatalk


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## MDShunk

I think you're missing some simple testing. When you expect the lights to be on, and they aren't, keep moving down the line with your meter to see where the power stops. 480 in a junction box? 480 to 277 transformer in the fixture? 30vdc power supply in the fixture? In my opinion, replacing that section of wire was a foolish thing to do without doing the testing to backp doing so. This should be a really simple thing to figure out with a meter and a ladder or meter and a lift.


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## gpop

MDShunk said:


> I think you're missing some simple testing. When you expect the lights to be on, and they aren't, keep moving down the line with your meter to see where the power stops. 480 in a junction box? 480 to 277 transformer in the fixture? 30vdc power supply in the fixture? In my opinion, replacing that section of wire was a foolish thing to do without doing the testing to backp doing so. This should be a really simple thing to figure out with a meter and a ladder or meter and a lift.


I have to agree. Meter says that the problem is in the power supply (driver) 277 to 30vdc. All tests point to that being the problem. Boss was sure it had to be a loose wirenut / broken wire in the insulation and by opening and closing the J-box and pulling the wires around we had to be causing the randomness. Sometimes its easier to pull 70' of wire just to rule out a problem. 

if you had 8 fittings x 4 drivers = 32 doing the same thing as in they work when they want to wouldn't you find that suspicious (actually its the fact that when they work they do so at the same time). 
If you installed a new driver (counts out temperature as a problem) and the meter showed it doesn't work (277v in 0V out) then 20 mins later its working wouldn't that make you think you have missed something.

I know switching power supply's can be a be hit and miss. Unplug the load then plug it back in and they work again for a while. (probably a self resetting fuse that's getting weak)

I can just make the call and have the vender come in under warrantee but I would like to check all bases first. 

It might be something as simple as we are running a little rich on voltage (487-489) this time of year as we are on very low load but you would expect to see that in the 480 to 277 switching power supply. 

funny that I preach "trust the meter" yet this time I can not follow my own advice.


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## wildleg

gpop said:


> ...
> Meter says there isn't a problem. ....


let me guess . . . you only used one meter, and it is a digital one.


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## gpop

wildleg said:


> let me guess . . . you only used one meter, and it is a digital one.


 
Interesting. 

I was using 2 but both were fluke t5 digitals so the 277 could be a false read if the drivers are not adding a resistive load. Dam I wish I thought of that and tested with the wiggy.

The 480v is real as the high bay that's near the end of the chain wasn't a problem.


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## telsa

The LEDs are getting 'synthetic' power from solid state electronics.

Woe betide you if you've got a flaky neutral, the reference point for said digital logic.

You can swing from everything is sweet to digital lock-up in the blink of an eye.

Near as I can tell you've spent all of your time looking at the Line Side with nary a peep at the Neutral Return.


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## Southeast Power

I might suspect those puck type 480/ 277 transformers.
The drivers are a mystery to me but they sometimes fussy.
Something degraded. 
We all know its not the circuit but for sure, the fixtures.
I would assume they took a hit or are failing somehow.
Is there a warranty available??


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## greenman

cheap drivers


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## Rora

gpop said:


> Went for another coffee come back and every fitting had some strips of lights on.


Think this is your most valuable clue.


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## Southeast Power

Rora said:


> Think this is your most valuable clue.


Whatever happened to the 'Light Emitting Decorations" guy??


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## gpop

Southeast Power said:


> I might suspect those puck type 480/ 277 transformers.
> The drivers are a mystery to me but they sometimes fussy.
> Something degraded.
> We all know its not the circuit but for sure, the fixtures.
> I would assume they took a hit or are failing somehow.
> Is there a warranty available??


Always a chance that something got spiked.

We have a 3 year warranty but im not sure if that is parts or complete units. Chances are they will send some one out to test them first.

The company is in the planning stage to change over thousands of fixtures to leds so they want to know what's wrong as these are meant to be install and forget. (justification for the upgrade is based on reduction of labor as a main selling point)


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## gpop

telsa said:


> The LEDs are getting 'synthetic' power from solid state electronics.
> 
> Woe betide you if you've got a flaky neutral, the reference point for said digital logic.
> 
> You can swing from everything is sweet to digital lock-up in the blink of an eye.
> 
> Near as I can tell you've spent all of your time looking at the Line Side with nary a peep at the Neutral Return.


dumb this down a little for me. 

We are old school so the lights are 480 single phase (no neutral). The switching power supply from 480 to 277v is in the light fixture. I had considered that the ground could be used in solid state switching so I did test that with the meter. I also considered that something else on the 480 like a hps light starter could be causing a problem. (I don't have a power quality analyzer to test for that).


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## MikeFL

gpop said:


> dumb this down a little for me.
> 
> We are old school so the lights are 480 single phase (no neutral). The switching power supply from 480 to 277v is in the light fixture. I had considered that the ground could be used in solid state switching so I did test that with the meter. I also considered that something else on the 480 like a hps light starter could be causing a problem. (I don't have a power quality analyzer to test for that).


When you measure it hot and say it's good line voltage, put a load on it and keep measuring the voltage. If it drops to zero, it's an open neutral somewhere. Without putting a load on it you could be measuring line voltage equivalent but without any current carrying capacity. Substitute neutral for one leg and same thing. A neutral is a leg. Simple way to do it is use a wiggy.


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## macmikeman

Southeast Power said:


> Whatever happened to the 'Light Emitting Decorations" guy??


I think he is with Elvis and Hendrix now.


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## splatz

gpop said:


> If you installed a new driver (counts out temperature as a problem) and the meter showed it doesn't work (277v in 0V out) then 20 mins later its working wouldn't that make you think you have missed something.


Me? I don't say, "hmm, this component is working now," I say, "this component is not working, it has an intermittent problem. intermittent problem." Intermittent problems are probably the single hardest thing in troubleshooting. 

Another real tough one with troubleshooting can be two problems that occur at the same time, you are trying to isolate one and there are two. 

I will bet you had some surge damage or something and all eight toasted the same way the same day. 

If they had failed all the way, rather than intermittently, you wouldn't even be scratching your head.


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## gpop

splatz said:


> Me? I don't say, "hmm, this component is working now," I say, "this component is not working, it has an intermittent problem. intermittent problem." Intermittent problems are probably the single hardest thing in troubleshooting.
> 
> Another real tough one with troubleshooting can be two problems that occur at the same time, you are trying to isolate one and there are two.
> 
> I will bet you had some surge damage or something and all eight toasted the same way the same day.
> 
> If they had failed all the way, rather than intermittently, you wouldn't even be scratching your head.


very well put.


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## 460 Delta

So I take it you are on a delta system, correct? Is the voltage up around 504 volts or so? 
That is pretty much the norm around here, so too high a voltage may be a concern.


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## gpop

460 Delta said:


> So I take it you are on a delta system, correct? Is the voltage up around 504 volts or so?
> That is pretty much the norm around here, so too high a voltage may be a concern.


Wye of the low side of the 25kv to 480v transformer. I can have the power company adjust the regulators during there next service as we are going to be on low load for months. We try to keep it under 490 as we have a lot of drives and anything over 500 can be a problem.


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## 460 Delta

Well @gpop, what was the answer to this puzzler? You were naughty and never got back with what you found wrong. Was it possibly untrue voltage?


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## gpop

460 Delta said:


> Well @gpop, what was the answer to this puzzler? You were naughty and never got back with what you found wrong. Was it possibly untrue voltage?


Left them on 24/7 and a few weeks later they failed one after the other. Vendor said it was due to high temperature in the roof area and as he spec'ed them he supplied the replacements.

I now have a fear of led lighting projects. We sell the projects on reduced maintenance cost over the life time of the unit then spend hours troubleshooting and replacing them.


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## splatz

gpop said:


> I now have a fear of led lighting projects. We sell the projects on reduced maintenance cost over the life time of the unit then spend hours troubleshooting and replacing them.


If anyone takes a hard look at the LED upgrades it's not a slam dunk. If you are gullible enough to let the sales rep from the lighting supply do the math, sure, they pay. But, if the customer does the math, it doesn't usually pencil out for the customer with the 50,000 hour fixtures hard wired. It _might_ pencil out with 100,000 hour fixtures cord and plug connected. But good luck finding the 100,000 hour fixtures you want. If you're building a million square foot warehouse they'll make whatever you want to order, but if you're buying 20, you're options are going to be a lot more limited than the catalog suggests. 

Believe it or not, it also might come out better to use new fluorescent fixtures wired out of the box for LED tubes if the in-house maintenance can change lamps but not fixtures. I mean better for the customer. 

And that's if you assume a very low fail rate, and you don't mind keeping some replacements in inventory, if you get lemons it's going to be dark and someone's going to the cleaners no matter what the spreadsheet said.


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## MotoGP1199

I have not had good luck with LED lasting in commercial settings near the hours they are rated for. I much prefer a standard fixture were the bulbs(florescent, led, etc, whatever you decide to use) can be changed out.


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## Olerando

I've had to replace my 16 led lights in my underground greenhouse cause they suddenly went down. I tested every little thing and that didn't give me much results. Sometimes they worked and sometimes the light wouldn't come on. I was so frustrated that I had to find some temporal replacements.


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