Was just wondering if I could put a 250 watt MH on a 400 ballast? :o After all, you can put any size bulb in your light sockets. I was thinking the 250 watt bulb would only draw thw current it needed from the ballast. This is a m59 magnetic ballast. It was FREE. Guess I could get a cheep 250 watt bulb from HD and try it. (and stand back if it explodes :-o)