Electricity Usage question

[Spikehs]

Ok, this may be a stupid question, but nevertheless... I was wondering how the watts of an appliance (ie MH 400w) relates to how much electricity it cosumes per hour? How much electricity would a 400w mh bulb use? (400w/hr?). Or is it based on how efficient the ballast etc, is? thanks! (I have use the rc calculator, i just wanted to know...)

 

[theatrus]

Ballast comes into it as well. Magnetic is about 80-85% efficient. Electronic is 90-95%. So for 400W magnetic ballast expect about 450W from the wall.

The best way it to use a watt-hour meter, such as a Kill-a-watt.

 

[8BALL_99]

The 400 watts stands for 400watts a second.. so that would be 4 Kilowatts per hour.. 100 watts for an hour -1kwh But your mh doesn't pull exactly 400 watts it might be 350 it might be 420watts. Radio shack sells a meter for about 30 bucks that lets you plug the device in then plug it into the wall it tells you the exact watts and amps it pulls.. Makes it alot easier to tell how much your pumps, lights and everthing else are really using..HTH

 

[8BALL_99]

lol he beat me to it... Kill-A-watt meter is what its called