Wattage of Ballast?

i know this is dumb but i have to ask anyways..

if i got like a 400 MH/HPS system with a cool tube i get that the bulb itself will be using a certain amount of wattage BUT my question is whether or not the ballast itself uses a certain amount of wattage as well?

aka is my 400w system truly running 400w or is it more than that? (i.e. the ballast runs an extra 30w or something?)

..just trying to calculate how much wattage im actually uses for the whole system.

this one: http://growace.com/product_info/400w-hps-mh-cool-tube-reflector-digital-ballast-grow-light.html

It runs more like 430 just like your thinking...

ok thats what i assumed thanks man. does anyone know how to find out exactly how much wattage a ballast runs? im assuming its different for 250 400 600 1000w systems? no?

good question i didnt even know that,, i was just assuming it used 600w like it says

it says on the box of a "400w plusrite hps bulb" how much the s51 ballast used. i cant remember though. im sure some simple googling will figure this out.

well, i googled it, and average for a 150 watt hps is approx. 567 watts for the first 15 minutes, then after the bulb is warm, 304 watts. this is info i got from an electrical site. i do not know if this is exact or even close.

yea ignore your lights rating, and just find out what your ballest pulls in for electricity. Easy way is to hopefully have it on it (should be) or look it up, even if its only a serial number you should be able to find it...

okay, i checked out the specifications on it. the s51 ballast (400 watt mogul base hps) pulls in 464 watts after the bulb is warmed. initial start up wattage was not mentioned by the company.

i really wanted to know because i have a 400 watter and the other website said its double the rated wattage.

hmm... there seems to be some discrepancies in places ive looked. i understand that the initial startup would require a higher wattage pull but my question lies in what the realtime pull is if you, for example, just run a 400watter 24/7? does it eventually die down to like 430-450? or is it running more like 500? i didnt think i was the only one with this question but i felt like an idiot for asking haha