40 lumes per sq foot? light question for professionals

[rx7_dren]

ok i was reading up on lights to choose and the majoriety of sites tells me to use a 400W MH or HPS in a closet space but in there teachings they say to use 40 lumens per square foot, oddly enuff the room they using is the same side of minz 8ft high * 6ft long * 3 ft wide so thats 144 square foot
no i times 144 * 40 lumes per square foot = 5760 lumens bulb i need to get then, so i found a site that has a 70W bulb that pushes that check it out www.amerilamp.com/metalhalide.htm, My question is why are they using 400W unless this is a new bulb?????

[Badass]

No mate... your calculations are a little off kilter... you want 50 watts per sqft. Height doesnt come in to it until youre working out which fan you want to use to extract. Let me explain a little... A 400W lamp is good for a 3x3 space.

3x3 = 9sqft.
400Watts/9sqft = 44.44444444r Thats near enough to 50/sqft. 50 is ideal, 40 youll get by 30 is minimal and anything below is pointless if you ask me.

This is what 58w/sqft will give you...





hope you can view those images... Theyre White Widow.