I just installed a double-pole 50A square D breaker (Q0250) in my box and when I flipped the breaker on it tripped the whole house. No load on the circuit yet, just wired up... Could I have wired it incorrectly? Wired the two hot leads on the breaker together to the positive on the device, then the neutral to the neut. Bus and the ground to the ground bus... That's correct right:confused:

Thanks much!

Oh.. and I had one circuit not come back on when I flipped the main back on no matter how many times I flipped the breaker- so I tried installing a new breaker for that circuit... still nothing- then I tried moving the breaker to a different slot and it worked fine. What gives?

Okay,

I have to guess at what you are doing here.
You are attempting to install a DPST 50 amp breaker into your main panel box?

First describe the conductor wire from the breaker to the load. Is it a #6/4 AWG wire?
If it is, then the Black lead would go into one side of the breaker, the Red lead into the other side of the breaker, White to the Neutral bus and both green and bare cooper to the ground bus.

''Wired the two hot leads on the breaker together to the positive on the device''

I don't quite understand.
Does that mean you connected both the black and red to the same terminal? That would create a major short. If you connected it to a device, how can there be no load?

I can't say how or why, but it sounds like the other breaker arced and burned the buss. Moving it would fix that problem.