# Thread: Volt Amps

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## Volt Amps

Have a site lighting drawing that say 20A circuits shall not exceed 1500VA and 15A circuits shall not exceed 1150VA. How do I make sure I don't put too many light poles on one circuit? Do I kneed to look at the fixture watts? Thanks.

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Originally Posted by mstrlucky74
Have a site lighting drawing that say 20A circuits shall not exceed 1500VA and 15A circuits shall not exceed 1150VA. How do I make sure I don't put too many light poles on one circuit? Do I kneed to look at the fixture watts? Thanks.
Yes, you need to start with the fixture watts, and know what bulb and driver will be fitted if there are options.
Then you look at the power factor (PF) of the fixture and divide the watts by the power factor to get the VA.

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Originally Posted by GoldDigger
Yes, you need to start with the fixture watts, and know what bulb and driver will be fitted if there are options.
Then you look at the power factor (PF) of the fixture and divide the watts by the power factor to get the VA.
Thanks.

4. Originally Posted by mstrlucky74
Thanks.
many times the fixture data sheet will list the amps
if it does va/fixt = voltage x amps
divide that into total va to get number of fixtures

5. Must be 120 volt circuits in your application, 1500 VA on a 277 volt circuit is only about 5.4 amps, advantages of using 277 over 120 kind of go away if you are still limited to 1500 VA.

6. Originally Posted by GoldDigger
Yes, you need to start with the fixture watts, and know what bulb and driver will be fitted if there are options.
Then you look at the power factor (PF) of the fixture and divide the watts by the power factor to get the VA.
Wouldn't the ballast or driver have all of that figured out and just give you the amount of current it draws?

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Originally Posted by infinity
Wouldn't the ballast or driver have all of that figured out and just give you the amount of current it draws?
It should. That would be the easiest path.
In some cases the driver may not give the current for each possible voltage or voltage range.

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