View Full Version : Will a 430w vs 270w ballast?

01-29-2007, 02:31 PM
I have a 430w son agro and ballast. I want to use a 270w son agro instead of the 430. Will the ballast work or do I have to purchase a new ballast for the 270w?

01-30-2007, 10:11 AM
Maybe, maybe not!
Sorry, but not having any actual experience, I'm going to say be cautious. Ballasts are designed to allow a specific in-rush of current to light the bulb then limit the current flow once the bulb has "ignited" and resistance to electrical flow is greatly decreased.
Using the higher power design of the 400 watt ballast with a much smaller bulb may be enough of a difference that the life of the smaller bulb will be greatly shortened -- may instantly!
Unless you have a very specific reason for needing to reduce the wattage, I'd stay with the 430. It gives more light, the electrical usage is not that much greater, the bulbs are about the same price and it gives you flexibility in growing area.

01-30-2007, 10:56 AM
The only reason I want to go with the 270w bulb over the 430w bulb is that the grow room is small (3L x 2W x 5H) I think that the heat generated by the 430 is going to be to high. I do have a intake fan and a exhuast fan by the light but not sure if its enough to cool it down.

01-31-2007, 12:29 PM
Can you mount your light on tip or your grow area (presuming it's inside now) -- even if this means cutting a hole in the top?
The difference in heat contribution between the two lights (including ballast loss) is approx. 600 btu. If direct heating by the light is not a problem on you plants with the larger bulb now, I don't know that you'd see that much of a benefit in going to a smaller bulb. I think ventilation is the solution.
By the way, I ran the bulb/ballast question past an electrical engineer who does industrial HID installations. He said "do not try to run a bulb off of a differently rated ballast" -- pretty much the same reasons I laid out previously. (Running a 430 on a 400 watt ballast is doable because there's a little leeway in design, but to 160 watts worth!)

of possibly ....
If heat is that much of a problem AND you need a new ballast, have you considered the high output compact fluorescents? I recently got two of these and they are doing a good job for lettuce. May be workable in your grow room depending upon what you are growing.

Sunlight Supply
02-07-2007, 08:54 AM
Hello, I would not recommend using the 270W lamp with the 400W ballasts. The ballasts will not know that you are using a lower wattage lamp, and cont. to send the entire current to the lower wattage lamp. Thus reducing the life of the lamp, and worse case making the lamp crack. 2x3x5 if you are air cooling is great for the 400W anyway. Good luck.