277V fixtures on 240V

[Smash]

I have a customer with a large shop. They wanted to take advantage of a massive energy rebate and purchased 50 LED linear high bay fixtures. The lighting rep assured me that they would run on 240V. I’m assuming a smart driver of some sort. I expressed my concerns to the rep that I was dealing with old 3 phase delta high leg that is also a little on the high side at 250V again she said no problem. Question will there be a problem ? It’s been my understanding that yes 277 to 240 is not a problem and the smart driver adapts to first incoming voltage but there’s no going back to any other voltages not that I would need to. I also have 10 of these fixtures battery backup. There is 480 V available however I’m not a huge fan of running these fixtures at that voltage. There is no 277 available with out a transformer. I’m simply concerned if these fixture will last. I will try and post the exact fixture being used.

 

[hillbilly1]

Don’t know where you heard no going back after first connection, but disconnecting the hot and neutral and applying a new voltage will reset it to the new voltage. Done that many times for temporary lighting before building had permanent power.

 

[Smash]

This is the fixture that was purchased. 120/277

 

[tortuga]

Your amperage might be slightly higher or you light output slightly less.
Having done quite a few retrofits I can say I have had only one issue in the last 10 years of doing retrofits and see 240 delta often. Before that we did have a few issues with electronic fluorescent ballasts when that was a thing. Some were rated 120 to neutral or 277 to neutral but did not play well on 240 L-L.
If its an open delta I dont put lights across the open phase.

 

[Smash]

Don’t know where you heard no going back after first connection, but disconnecting the hot and neutral and applying a new voltage will reset it to the new voltage. Done that many times for temporary lighting before building had permanent power.

That could have been a while ago when they were first made available. I guess I’m not understanding the concept of applying one hot 277v leg and a neutral to 240V now two hots no neutral.

 

[kwired]

That could have been a while ago when they were first made available. I guess I’m not understanding the concept of applying one hot 277v leg and a neutral to 240V now two hots no neutral.

It is all about whether the power conversion circuit can handle said input voltage. AFAIK these typically rectify incoming voltage and then end up reducing that voltage to whatever the actual utilization volts is for the LEDs. They may even work with input below 120 as long as it doesn't go below what is needed by the output side. They might work above 277 as well but the higher you go the more you risk breakdown of insulation of some components or end up with "reverse avalanche" of solid state items.

 

[LarryFine]

Those lights should run on any voltage between 120 and 277, and should not care whether it's L-N or L-L.

 

[LarryFine]

That could have been a while ago when they were first made available. I guess I’m not understanding the concept of applying one hot 277v leg and a neutral to 240V now two hots no neutral.

Again, the drivers should function without one conductor having to be grounded.

These are equipped with AC-to-DC power supplies, not fluorescent ballasts.

 

[Flicker Index]

Many LED ballasts have RFI suppression and surge protection built-in. 120-277, generally intended for use with either N-120 or N-277 does not mean that it is allowed to be used under every plausible conditions where it is 120 to 277v between two wires.
It might be able to have both legs 120v above ground, but maybe not be safely and reliably have 240v persistently applied with respect to case. (connected between A and C with B phase grounded on a 240 corner ground. That means there will be 240v between both lines, and 240v between each line and ground).

LED ballasts are mass produced and they look at every place they can to shave fractions of a cent and that might mean using s suppressor or capacitor between case and white that does not like having 240v between white and ground.

it can reliably operate with both legs being pulled to 240v to ground, such as in the case of corner ground delta, which is plausible for some old commercial buildings.

It might having both legs at 120v across two lines for 240v between lines and 120 to ground

GE's miniature transformer for getting 277v from 480v for example specifically denounces use on ungrounded delta, or between two floating legs.

https://dyna-brite.com/Merchant2/spec_sheets/GETR480277.pdf

Again, the drivers should function without one conductor having to be grounded.

These are equipped with AC-to-DC power supplies, not fluorescent ballasts.

Though the back-end is different, the front end of LED ballasts and fluorescent ballasts don't differ much.