Calculations for fixtures with ballasts

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Highlow

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Hello all. I'm trying figure out in my calculation, should I include .30amp an electronic ballast with 3tube 2x4 fixture. If 3 tubes draw 96watt, should I include .30amp ballast which will be 83.1watt. So the whole fixture should be counted as 179watt? Voltage is 277v.
Thank you in advance for the input. It does sound like a lot for 1 fixture especially when you figure continues running, which only gives you 16amp to play with?
Maintenance guy...
 
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Highlow said:
Hello all. I'm trying figure out in my calculation, should I include .30amp an electronic ballast with 3tube 2x4 fixture. If 3 tubes draw 96watt, should I include .30amp ballast which will be 83.1watt. So the whole fixture should be counted as 179watt? Voltage is 277v.
Thank you in advance for the input. It does sound like a lot for 1 fixture especially when you figure continues running, which only gives you 16amp to play with?
Maintenance guy...
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I believe you just need the ballast info and not the lamp wattages. At least That is what I think....
 
The branch circuit does not 'see' what the bulbs are doing. Only the ballast does. So calculate based solely on what the ballast draws, and ignore the lamps. If you don't know what number to use, look on the ballast or contact the manufacturer (or go to their web site).
 
First off you're confusing Watts with VA. If the ballast draws 0.30A at 277V then the ballast draws 83.1 VA. I don't know how you went from 83.1 to 179.

If you're doing this calculation for LEED or ASHRAE 90.1 then you'll need Watts, not VA. The ballast cutsheet should show Watts when operated with (3) 32WT8 lamps.
 
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