Feeding exterior lights with 480V, single phase 1

[powergage]

I am looking to install several 1000W exterior lights at our facility. I have been told by the vendor that I can supply any voltage that I want and he will select the ballast accordingly. All of the 277/480 lighting panels that are nearby are fully loaded, so I am looking at feeding the lights directly from a spare 480V, 3p breaker in a nearby MCC. Question #1: Is this a good idea???

If I do this, I would distribute the lights as evenly as possible on the three phases. I.e. connect three fixtures across phases 1 and 2, three fixtures across phases 2 and 3, and four fixtures across phases 1 and 3. Question #2: Is this the correct layout and/or am I doing something wrong here?

Thanks!!!!

 

[rbulsara]

nothing wrong, imho. In fact it is how it should be done.

 

[AndyLyke]

Just make sure that the manufacturer's ballast and fixture are designed for ungrounded source. You'd probably want to ground the fixture housings. I think it depends on the manufacturer to specify the design. If the source is ungrounded, you can get 480 to ground if one corner does have a ground fault.

 

[powergage]

Thanks for the help! I have notified the manufacturer that we will be supplying 480V, 3-phase power and they are choosing the ballasts accordingly.

It sounds like a very good suggestion to make sure the fixture housings are grounded. I took a look at some of the manufacturer's other setups and I don't remember seeing a ground wire running to any of the fixtures themselves. I'm not sure exactly how to tie the ground in, with the ballast in the circuit.

gage

 

[rbulsara]

ground wire connects to fixture enclosure and metal pole ( if its metal). There should be terminal in the fixture marked for grounding and there usually a ground "pad" or a surface near the bottom of a metal pole, accessible through an hand hole (cut out).

It is always a good idea to have a ground rod for each pole coonected to the same ground lug. A local grounding rod is a supplement while, ground wire along with the circuit is a Code requirement.

 

[rbulsara]

Ground rod would a 1/2" dia meter x 8ft. long driven in to the ground and connected to the pole via copper condcutor. This only done for large poles like 25' or 30' tall. Idea is to have pole (and hence anythig attached to it , like the fixure) firmly grounded even if the equipment ground conductor in the circuit is severed. As I said, this is not a code requirement, but a widely accepted good practice.