Steet Lighting Voltages

[tom baker]

I have a request from a friend for information on the following:
"I'm looking for something on the pros, cons, and issues with different voltages (120, 240, 480). The other topic that we need to cover is the issue of the type of wiring (2 wire, 3 wire, dedicated circuit)"
Any suggestions on resources?
I pretty much know the answers, but want to see what else is available.

 

[hurk27]

Re: Steet Lighting Voltages

Tom I'm sure you know this, The length of the run and voltage availability should dictate which to use. If I had a run over 300' and available fixtures and voltage could be 480 then that would be the best cost efficient way to feed them.

As far as how many circuits? I would alternate fixtures across all three phases to maintain some light in all areas, if one circuit fails. Even doing this down to each pole if there is enough fixtures on each pole. This way if one circuit fails because of shorted ballast or wiring. this way you would not have any dark spots just a lower availability of light.

 

[eesac]

Re: Steet Lighting Voltages

If you are just talking street lighting, 120 V is predominant in California, at least northern Cal. It is because (as I was told) utilities can easily tap into a 120/240 or 120/208 V TFR, which are much more available than 277/480 V TFR's. A lighting agent we work with that I know indicates that 95% of their street lighting sold is 120 V, and the rest at 240 V. We have designed some street lighting, and they are all 120 or 240 V. A good way to find info is to call a local lightin agent to see what they sell, call the local utility or city public works. The only con of 120/240 is voltage drop of course, but the ease of getting power outways it.

In parking lot lighting design of medium to large facilities, if 480 or 277 is available we use it as much as we can.

As far as wiring, there are too many factors that dictate it; distance, how you want lights controlled, what lights on what schedule, using 1-pole 2-pole or 3-pole bkrs. For street lights we use 3-W for 120 V and and 2-W for 240, and fill the conduit as much as we can.