wattage vs actual power usage

[beattyr]

Trying to work things out in my head here for power consumtion.
Standard 250 MH light. Emits the equivalent of 250watts in light power correct? In other words, you could convert the wattage into Lumens which is the measurement for light intensity.
Its actual power consumption, ie at the meter, is something different no?
Thanks
Rob

 

[bang guy]

Yes but it depends on the ballast. Adding 10% is generally in the ballpark but Some ballasts underdrive lamps and some overdrive them.

 

[skirrby]

the auctual power usage is in amps.. the meter measures amps... best way to find out how many amps something uses. is watts divided by volts(120 for a house) = amps.
example. my lights are 260 watts divide that by 120 and you will see how many amps. so 260/120=approx 2.166 amps.
does that make any since? also if you know how much the powercompany charges per amps being drawn.. you can see how much it will impact your power bill. as far as i know thats how it all works