Blowing main fuse with new ballast?

I have a 200 amp service and I have an 8 light controler running 8 lights normally and a 5 ton central ac and about 8 fans running. I have had this set up running for almost one year without any problems. I recently added another four light controller on a 30 amp circuit running 2 lights for a total of only 8 lights with 2 new ballasts and I blew one leg of the main twice. Each time it took a few hours. So I took out the 4 light controler and stopped using the new ballasts and it has been running with 6 lights for 2 weeks without a problem. One of my five year old ballasts stopped working so I replaced it with one of the new ballasts and blew the main again after a few hours.

My question is can a ballast have a short or a problem that can blow the main without blowing the 50 amp circuit that the controler is one?

Hard to say, could be a short or your new ballast is drawing more than your old, sorry, that's the best I can do.

I'm thinking it's a short because if it was drawing to much it would blow the 50 amp circuit not the main. I'm just hoping to hear from an electrician if it's possible. I brought the ballast back to the store and he is going to run it. I'm hoping he blows his main so I at least get an answer.

Are you saying the ballast blows the main but not the 50 amp breaker? that doesn't make sense, at least to my understanding, as said, your best bet is to have an electrician look at it.

Yes and it doesn't make sense to me either. I have been running for 32 hours now after replacing the ballast without an issue so I'm hoping that that was the problem. If it blows again I'll have an electrician come and check it all out.

The main breaker goes bad for whatever reason. Replace the main breaker.

Possible what computergroove said, may be good idea to replace the main.

Is the insulation on the feeder wire going to the main fuse that was blowing unusually hot? If so, you could have a slighty loose connection that causing the wire to get excessively hot, thus was blowing the fuse.

Had an electrician come today and he is convinced that it was the new ballast. The main is a double 100 amp fuse so it is not that because they blow when they are bad and everything else checks out. I just have to wait and see..

usually when only one leg of the main blowing its because that side is overloaded with amps. might need to do an volt /amp and see where your loading up at then you can start buying stuff. good luck.and remember if something is unusually hot it may lead to fire.. be the person who lives and writes about not the person we read about being dead..