Quote Originally Posted by smpaz420
will a 600 watt ballast run a 400 watt bulb without hurting it?
Do not run a 400watt bulb on a 600watt digital or coil ballast, they're rated for a specific wattage for a reason.

600MH bulbs and ballasts are no longer manufactured... haven't been for a few years now..

I think you're stuck looking for a conversion bulb.. but the other benefits of running a digital ballast are still there.

Enjoy
Bob.