I have a main panel with a sub panel feeding off of it. The main panel has ground rods and the ground / neutral our bonded. The subpanel is fed off of the main panel with 4 wires (2 hots, neutral, and a ground). However in the subpanel I have two grounding bars. Is the frame enough to connect those two ground bars or do I need to run a certain gauge of copper wire between them? Also I do have neutral bars in the sub panel; and the neutral bars are NOT bonded to the panel or ground bars.

When I turned off one bathroom light last night (Wednesday), the circuit breaker is tripped. Then I cannot reset the tripped circuit breaker - as soon as I reset it it is tripped again. I did install one light in a bedroom last Saturday. The light works well and was not on when this happened. I know there must be somewhere with short circuit, but where should I start? The breaker controls nearlly 20 places. BTW, I did touch the bathroom light weeks ago, trying to get one bulb off. I tried so hard that the "head" where the bulb goes in was damaged and the buld can still not be removed.