Initially, the facility Engineer at the place where we are upgrading their parking lot lighting to LEDs, wanted us to use one leg, of the two 277VAC legs comprising their 480VAC feed from the street transformer, and cap the other one off. I soon learned that this was not according to code here in South Florida, and have had a 480VAC LED made for us in China. However the LED reasonably comes with a L (line) and a N (neutral) connection.
Question: "Can the two 277VAC feeds simply be joined to feed the 480V the LED requires or is it more complicated?"
At my business I join 2, 120VAC lines from different fuse boxes to make a 240VAC feed so provably not different but wanted to check before doing something wrong to a customer's electrical system.

 

I think we should be careful about giving you advice and you should be careful about taking it from anyone but a qualified and licensed electrician. The liability exposure here is enormous. But you do whatever you want cuz ultimately it is on your hook.

Would it be impertinent to point out that you are not actually making the LEDs -- just installing them?

 

I think we should be careful about giving you advice and you should be careful about taking it from anyone but a qualified and licensed electrician. The liability exposure here is enormous. But you do whatever you want cuz ultimately it is on your hook.

Would it be impertinent to point out that you are not actually making the LEDs -- just installing them?

Thank's for the reply. Indeed we are not making LED chips. There is only one company in the US that actually makes them, Cree Co. in Durham NC. Not Phillips or GE or any othe,r to my knowledge, make the actual chips, here in the US.
That said, while we buy the chips from China, as do GE, Phillips etc. we use everything we possibly can from here, which leaves quite a bit. Housings, heat sinks, wire, reflectors, etc. The assembly is done here in South Florida. So, are we 100% made in America, I guess not, but we are a lot more 'Made in the USA' that 99% of what you see on e-bay or Amazon.
Re: Liability, keep in mind that we make parking lot lights, that are on 40' poles, outside, in a parking lot, with our own installed fuses. Not like in someone's house.
Steve

 

Initially, the facility Engineer at the place where we are upgrading their parking lot lighting to LEDs, wanted us to use one leg, of the two 277VAC legs comprising their 480VAC feed from the street transformer, and cap the other one off. I soon learned that this was not according to code here in South Florida, and have had a 480VAC LED made for us in China. However the LED reasonably comes with a L (line) and a N (neutral) connection.
Question: "Can the two 277VAC feeds simply be joined to feed the 480V the LED requires or is it more complicated?"
At my business I join 2, 120VAC lines from different fuse boxes to make a 240VAC feed so provably not different but wanted to check before doing something wrong to a customer's electrical system.

You do NOT EVER "join" the different phases!! That leads to nasty destruction and potential injuries. Standard 480 volt 3 phase power has 480 volts potential between each phase and the others. In addition, each of those same 3 phases is 277 volts above the neutral wire. Using a single 277 volt line for lighting in commercial buildings is quite common, and it works well. The benefit is that one side of the supply is grounded. while using the 480 volts has nothing grounded..The advantage is that for a given power level less current is needed, the downside is that both lines must be switched.

 

Thank's for the reply. Indeed we are not making LED chips. There is only one company in the US that actually makes them, Cree Co. in Durham NC. Not Phillips or GE or any othe,r to my knowledge, make the actual chips, here in the US.
That said, while we buy the chips from China, as do GE, Phillips etc. we use everything we possibly can from here, which leaves quite a bit. Housings, heat sinks, wire, reflectors, etc. The assembly is done here in South Florida. So, are we 100% made in America, I guess not, but we are a lot more 'Made in the USA' that 99% of what you see on e-bay or Amazon.
Re: Liability, keep in mind that we make parking lot lights, that are on 40' poles, outside, in a parking lot, with our own installed fuses. Not like in someone's house.
Steve

I take your point; assembling things is a good business. My point with respect to liability is that if you do something that causes a future maintenance person injury, you and your insurance carrier may be on the hook for a big settlement. This forum is not the place to ask for mission critical advice and most folks here are reluctant to give it. I'm just advising you where to go to get the information I think you need. Take my advice or don't take my advice -- it doesn't matter to me which way you decide.

 

I take your point; assembling thing is a good business. My point with respect to liability is that if you do something that causes a future maintenance person injury, you and your insurance carrier may be on the hook for a big settlement. This forum is not the place to ask for mission critical advice and most folks here are reluctant to give it. I'm just advising you where to go to get the information I think you need. Take my advice or don't take my advice -- it doesn't matter to me which way you decide.

EVERY lighting installation that I have seen that uses the 480 volts connection is actually a 277 volt connection between one of the three phases and the neutral. Even on parking lot lights, the control system only switches one line, not both. The serious flaw that the facilities "engineer" has ignored is that with 480 both sides need to be disconnected to be even slightly safe. I have smelled a set of parking lot lights destroyed by the excessive voltage, here in southeastern Michigan. The smell, outside, 2 days later, was still nasty smelling.
My guess is that the facilities person is attempting to compensate for not having an adequate neutral connection to the light posts. That is a common installation error done by less qualified electrical contractors, to save a little money.

 

English language isnt always easy even for native speakers

Can the two 277VAC feeds simply be joined to feed the 480V the LED requires or is it more complicated?

Probably he means using 2 lines from two 277V phases, giving the 480V he wants.
Thats pretty the obvious.

Connecting them to each other wont make sense.

A 480V device with L and N very likely is not for 480 but for 277 using one phase + N.

Id say so. If it doesnt light up you could try between phases (laughing).

 

This is a uncomfortable subject for moderators because LED to mains is banned as part of our Terms of service however this is a case of a a black box commercial hardware so it slips through the cracks and is allowable as such.

 

https://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/special-purpose-diodes/ follow this article to the section on LEDs and you will get more information on LEDs. Never mind someone has edited th article You can use a capacitor as a ballast.

 

Initially, the facility Engineer at the place where we are upgrading their parking lot lighting to LEDs, wanted us to use one leg, of the two 277VAC legs comprising their 480VAC feed from the street transformer, and cap the other one off. I soon learned that this was not according to code here in South Florida, and have had a 480VAC LED made for us in China. However the LED reasonably comes with a L (line) and a N (neutral) connection.
Question: "Can the two 277VAC feeds simply be joined to feed the 480V the LED requires or is it more complicated?"
At my business I join 2, 120VAC lines from different fuse boxes to make a 240VAC feed so provably not different but wanted to check before doing something wrong to a customer's electrical system.

I so not live there so cannot comment on local standards but it is common that GND is not permitted as a current carrying conductor - it is used for protection. hence putting current to GND is of course not permitted... this is where N comes in.

Also
2*120V=240 V
and
2*277V <>480V (off by 74V).
will it work? try... it may light up but it will not be nearly as bright as intended.

and ... since you are doing assembly... what stops you from making assembly that will work at any given voltage? simply adjust number of elements...

 

This is a uncomfortable subject for moderators because LED to mains is banned as part of our Terms of service however this is a case of a a black box commercial hardware so it slips through the cracks and is allowable as such.

Wendy, THANKS!!! It is awesome that an online discussion is actually watched by somebody who understands the stuff being discussed. I am really impressed. And also I really appreciate being notified that a given posting is old. Eventually I will learn my way around this large discussion area, I hope. Now as for misinterpreting things like "joined together", I tend to take all stuff quite literally because of some experiences that I have had with some people over the years. So I tend to assume that folks would do exactly what they say, and thus I toss in a caution, which may, or not, be needed. And I have observed that in some of these discussions some folks appear to lack any background at all in the area of electrical stuff.I did not want one of those folks getting zapped.