I have a question regarding system watts in a 2 lamp ballast. Why is the system watts less than the actual wattage of the 2 lamps and ballast? On a GE232MAX-L/ULTRA, using two 25W lamps at 277V, the system watts is 39W. The power factor is high, 99%, but not 1.2 as the system watts suggest. Am I not understanding what system watts means? We are having a problem with the projected savings and power consumption at a facility we looking to retrofit.
Ballast system watts
- Thread starter solis
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Electric-Light
Senior Member
Most ballasts today for commercial use have a PF of >0.98, and its not relevant for your energy saving calculation.
You're using lower wattage, because it is an under-drive ballast. (0.77 BF) It's designed to operate two F32T8 to produce 77% of rated lumens +/- 10 pts from that or so for 48"T8 25W. Look up the specs on GE site using the product code printed on label for exact operating parameters with 25W lamps. System watts is the power going into the fixture under whatever configuration you made.
What you need to understand is that lamps are driven to produce 77% output. If you thought you're getting 100% of rated lamp output while only using 19.5W/lamp , you're sadly mistaken.
Electric-Light
Senior Member
72130 F32T8/25WSPX41EC 38 new3850 mean3619 lpw 101 4100.0 85.0
So, while you'll get 95 lumens per watt and use only 38 watts but you're only going to get 3620 lumens from a two lamp setup.
So, you're looking at substantial reduction in output. 3619 lm using 0.77 BF and 25W 48" vs 6440 lm using 1.15 high BF(which is apparently what you thought you have) 32W 48"
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