i am currently installing recess lights , I ran a new line to the breaker box for a set of 7 lights , my problem is that in one of the recess light boxes i have another line inside the same box.if i connect the ground line from both lines it blows the fuse!! Am i not aloud to do this? must seperate lines be in different boxes? or did i ground the line wrong in the fuse box?

NOT SURE WHAT'S YOU ARE SAYING. MAYBE THE WIRE THAT WAS ALREADY THERE IS A SWITCH LEG.IF THAT IS THE CASE WHAT APPEARS TO BE GROUND IS HOT WIRE COMING FROM THE SWITCH.HOPE THAT WILL HELP AND MAKE SINCE TO YOU.GOOD LUCK

Interesting problem, however, I also do not know what your are trying to say. Try to be a little more clear on this other line you are talking about.

All ground wires do indeed get connected together and in the panel box it gets connected where all of the other ground wires get connected. The only way it would cause a short there is if you connected it to the fuse lug. Grounds do not cause short circuits. Shorts are caused by a hot wire touching the ground.

Following up on what dr home said: A hot wire is touching the ground wire. When connecting the wires in the problem box, use wire nuts!! Make sure the nuts cover all the exposed wire on the hot (black) and neutral (white) wires.

Also, it would help us diagnose the problem if we knew more about the circuit. Is this extra wire going to the switch or another light. You make it sound like the lights are wired in parallel and not in series. Where do the wires for the other lights tie together? in a junction box, at the switch, at the breaker???

Post again and let us know.