277/480 v parking lot lights

[Martin22]

Hello fellow electricians I am new to the group and looking for some help.
I recently was given a job to troubleshoot some newly installed parking lot lights that were failing a few days after the install. The incoming power is 3 phase 480v the lights will operate at 277/480v and the lights are currently being ran on 480v...they connected the phases correct and the lights are running off of 487 which those lights are working ok but the lights that are failing have 492v being supplied to them..the lights should still work off that voltage but led light drivers are sensitive to high voltage I am looking to convert them to 277 but how do I do this do I use one 277 leg and a nuetral? And please explain how a nuetral works in a 480 power distribution center...

 

[Dsg319]

Hello fellow electricians I am new to the group and looking for some help.
I recently was given a job to troubleshoot some newly installed parking lot lights that were failing a few days after the install. The incoming power is 3 phase 480v the lights will operate at 277/480v and the lights are currently being ran on 480v...they connected the phases correct and the lights are running off of 487 which those lights are working ok but the lights that are failing have 492v being supplied to them..the lights should still work off that voltage but led light drivers are sensitive to high voltage I am looking to convert them to 277 but how do I do this do I use one 277 leg and a nuetral? And please explain how a nuetral works in a 480 power distribution center...

To change your current set up to 277v at the light all you need to do is take one of the phase conductors and land it on the neutral bar and change your tap in the light to 277v.

Now what size conductors your using and/or if it’s single conductors can throw a wrench in plans as to re-identifying as a grounded conductor. Me personally would not care what size they for the fact of being complaint to re-identify or not. They are already pulled in and there so I would just tape it grey and go on with my life.

 

[augie47]

If your problem is indeed high voltage on the 480 circuit I would not expect any great improvement by going to 277

 

[roger]

And please explain how a nuetral works in a 480 power distribution center...

A 480Y/277 volt system works the same as a 208Y/120V system. You have three 480V windings connected together at one end of each winding (a wye configuration) and grounded at this point which is now the neutral point.

 

[ptonsparky]

What are the measured L-N voltages?
What are the measured L-L at the source?
At Load?
Picture of fixture label?

 

[Fred B]

What is their location the lights reading the higher voltage in comparison to the lower voltage reading ones? Voltage drop might be your freind if the lost lights are closer to the power source than the ones not failing.
What is voltage at source panel?
But a 2.5% increase over standard is not much and should be well within the limits of +- of the fixture ratings.
As @augie47 said if high voltage is the issue it would not be resolved by going to 277 off the same 480 source, as the comparison 277/480 is same as 120/208 or 120/240.

 

[Martin22]

The driver on the lights are 277- 480 if I switch them over to 277 I will have way more range to be within the 480v ?
Phase A-B 492v
Phase A-C 485v
Phase B-C 485v

Nuetral To Phase
A 288v
B 287v
C 287v

The lights that burnt out vary in range from the power source. The closest light is 20ft away and the furthest about 100 yards

 

[Martin22]

I am still trying to figure out how to upload photos so you guys can see what I'm working with

 

[LarryFine]

A 480Y/277 volt system works the same as a 208Y/120V system. You have three 480V windings connected together at one end of each winding (a wye configuration) and grounded at this point which is now the neutral point.

If I may, you mean three 277v windings in a wye configuration.

 

[LarryFine]

The driver on the lights are 277- 480 if I switch them over to 277 I will have way more range to be within the 480v ?

Yes, if you're talking about a two-wire input, and not separate inputs (taps) for each voltage.

 

[ptonsparky]

Yes, if you're talking about a two-wire input, and not separate inputs (taps) for each voltage.

Aren't most of the power supplies two wire for LED?

 

[LarryFine]

Aren't most of the power supplies two wire for LED?

Yes. I was just being thorough in my answer, especially in response to things mentioned in posts 2 and 3:

To wit: "change your tap in the light to 277v" and "If your problem is indeed high voltage on the 480 circuit I would not expect any great improvement by going to 277"

 

[roger]

If I may, you mean three 277v windings in a wye configuration.

Oooops, you are correct Larry. Must have been before the coffee kicked in.

 

[synchro]

To wit: "change your tap in the light to 277v" and "If your problem is indeed high voltage on the 480 circuit I would not expect any great improvement by going to 277"

A question is whether the driver can accept voltages over a 277-480V continuous range without having separate taps for 277V and 480V operation. If so, the OP could have a point that wiring it for 277V would make it less susceptible to overvoltages. But then it might be more susceptible to dropping out due to undervoltages, but still preferable to having failures. The higher current draw when running off 277V is also going to increase voltage drop on the conductors, which need to be rated for that current.

 

[Jraef]

My suspicion is in the specs on this “277 - 480V” driver. 99% of these come from China where they don’t have 480V. 480V only exists in North America, which is only a fraction of the world market. So the chances are good that these were actually designed around 400Y230V systems, which are more common around the world, then with maybe a +20% tolerance which put them at 480V. But that would be 480V +0%, yet our utilities can go +5% and still be within spec.

Just a guess though based on my experiences with Chinese designs on things labeled as “480V”. It would be more telling to see their actual specs on the drivers.

 

[electrofelon]

My suspicion is in the specs on this “277 - 480V” driver. 99% of these come from China where they don’t have 480V. 480V only exists in North America, which is only a fraction of the world market. So the chances are good that these were actually designed around 400Y230V systems, which are more common around the world, then with maybe a +20% tolerance which put them at 480V. But that would be 480V +0%, yet our utilities can go +5% and still be within spec.

Just a guess though based on my experiences with Chinese designs on things labeled as “480V”. It would be more telling to see their actual specs on the drivers.

Fixtures are required to be listed. Seems like the standard and/or testing would disallow such a stupid design no? Or maybe this is yet another time we ask ourselves "what exactly is listing accomplishing?"

 

[mtnelect]

As I have been driving around different shopping centers that have been converted to LED lighting. I have noticed several pixels in each fixture have gone dark; I have been thinking these LED fixtures must have been made in China.

 

[Jraef]

Fixtures are required to be listed. Seems like the standard and/or testing would disallow such a stupid design no? Or maybe this is yet another time we ask ourselves "what exactly is listing accomplishing?"

China, faking listing marks? Whaaaat??? (/s)

People looking to save a few bucks are constantly shopping on-line now and a lot of even professional buyers do not know to ensure that something electrical is NRTL listed, and/or they ask the question, get a bogus response and just accept it, because they WANT to be able to get the bargain that they found. Couple that with a “maintenance” retrofit project where no permit was taken out, so no inspection called for, I can see it happening.

I just had a customer have a bunch of defective Siemens 1500 PLCS fail right out of the box. Turns out their buyer found a “bargain” on them at a Chinese e-commerce site where they were less than half of the normal price. They were all fakes, but not technically counterfeit because they didn’t actually say Siemens on them, just the part number was the same. No response from the seller.

 

[AC\DC]

I must be missing something but could you use a buck/boost transformer like this https://www.larsonelectronics.com/p...80v-primary-460v-secondary-32-82-amps-50-60hz
and get your voltage in your parameters

 

[Another C10]

If your problem is indeed high voltage on the 480 circuit I would not expect any great improvement by going to 277

Id think if he's getting 492 on the failing lights then the 277 may be 289 ? or maybe 283v