Light size for how many plants???

So how many plants can you SUCCESSFULLY have under each wattage of light. Say 400w,600w,and 1000w...

i fit 3 under a 600

Depends somewhat upon the size of the pots and the anticipated plant size. What you should look at first is the size of space a light will cover;

General rule of thumb is 50w per square foot of floor space.
WATTAGE -- COVERAGE
1000 watt - 4 to 5 feet across (1.3 to 1.5 meters)
600 watt - 3.5 feet (1 meter)
400 watt - 2.5 possibly 3 feet (.8 to .9 m)
250 watt - 2 feet (.6-.7 m)
175 watt - small, less than 2 feet

I like trees so 2 under 400w and 3 under 600w and upto 6 under 1000w.

I just had 20 under 2 lights. Started with 1000 watt, had to switch to 600 cuz my designated 30 amp breaker kept tripping. So I had 10 under 600 watts in a sealed room with CO2. temps were always 75-78 lights on. I used to have 6000 watts for 36 plants. Now 1200 for 20.
It turned out to be an awesome grow. Wish I could have left the 2x1000 hps running. But my electric bill was pretty managable.

I have 6 under a 1000 watt HPS.

i have 6 under a 400, cramped though, and im doing a LOT of training, shooting for 3 oz off a plant so nothing huge, a fair sized plant though, i would say tree level plant should yield anywhere from 1-3 pounds so if there is 2 1 pound plants under a 400 then 6 plants that yield three oz should, in theory, take up half the space, but it would probably even out

phxrocks said:

I just had 20 under 2 lights. Started with 1000 watt, had to switch to 600 cuz my designated 30 amp breaker kept tripping. So I had 10 under 600 watts in a sealed room with CO2. temps were always 75-78 lights on. I used to have 6000 watts for 36 plants. Now 1200 for 20.
It turned out to be an awesome grow. Wish I could have left the 2x1000 hps running. But my electric bill was pretty managable.
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Your wireing has issues. Someone probably put a 30 amp breaker on wireing to small to handle the load. Homes generally do not have 10 guage wire unless it is a 220v circuit. Anything less than 10 guage will overheat and trip the breaker with 2 1000w hps. 2 1000w lights will pull just over 18 amps. Thats too much for a 20 amp breaker and most likely your wire overheats because it is too small and trips the 30 amp.