Auto Parts: Electrical problems, 1978 buick electra, batt cables

Question
I have a 1978 Buick Electra overall in very good condition, but recently I've been having some electrical problems, I've been told that era of car style basically are the same (i.e.) Chevy's,Buicks,Olds,etc.  First off my interior/door/dome lights will not go off unless I take out the fuse, and my parking lights will not go off unless I disconnect the battery. At the same time I just found out the negative terminals wire comming from the battery is a little frayed and some wire is showing, I've had to jiggle it a bit to get power, could that be part of it? Yet I've been told to check my fusible links,relays, and circuit breakers but I'm having a hard time finding them. Could you help me understand this problem and if its links,negative terminal wires,etc. could you help me locate them, I'd greatly appreciate it.  

Answer
I would start by replacing both batt. cables. If that doesn't fix your problem try running a new ground wire from the engine to the car body or frame. You can do this just about anywhere you have room. I would recommend at least a 12 gauge wire for this. if that doesnt work i believe you have a short between two wires. Too track that down i would start by pulling the other fuses to see if any of them will shut of the lights. Just for giggles have you checked the light switch it self? good posability it might be shorting across the contacts.