Brake lights pull voltage way down

My bike is an 82 KZ1100 D1 SPECTRE. Whenever the brake lights are on,(has 4 extra lights in dealer installed back box)the h-light goes dim & batt volts drops like a rock.I have diconnected the back box & still have the draw.Also ocasionaly the 30 amp main fuse will fail but not in the center, it burns on the ends??? Does anyone
Know of a common fault I can look at?

If the stock rear light is still plugged in then unplug it from the harness and see what happens. If it still drops voltage or blows the fuse then it has to be in the harness or switches.

The fuse burns on which end--the lights, or the juice? I'm guessing the lights end.

Do like KZ Rage says, and if that doesn't work, leave the old bulb and new box disconnected/removed, remove the fuse and, using a stock voltmeter (the simpler the better; the ones that older Baby Bell techs used is best) turned off, put one end to the frame for ground and the other to the lights end. If the needle moves in either direction with the meter turned off, you've got some stray voltage leak (least likely); if it doesn't move, turn the meter on and see where the needle goes. If it moves to the right (very likely), either completely or partway, you've got wiring problems. Start tracing the wiring, looking for insulation breaks, or even connector points, that might be touching the frame somewhere.

Realistically, it's most likely something relatred to the lights installation, whether it's the existing lights or the new stuff.

Thanx guys .I was realy looking for a common place where
the harness will rub or short to ground.Or acommon switch problem. I can't find anything wrong with either.

If it was a short, the fuse would blow, not just melt in one end or the other. Fuses melting at one end are ususally the indication of a bad connection on the fuse. With the extra current to the brake light (which is significant) the bad connection gets hotter and the resistance goes up. That resistance is the cause of the voltage drop. It also causes more heat which melts the fuse. Make sure the connections are clean, shiny brass and fit tight. If the wires are melted, consider replacing the fuse holder with a much better, sealed blade-type fuse holder.

Check am make sure you have a good ground also. Beleive me a bad ground will play havac with electrical problems when diagnoising

Just a thank you note to all who responded. Have been busy at work & hav'nt made the sugjested checks as yet but I am sure I will find the answer. When I get a few bucks ahead I will be sending some KZR's way.

INLINES RULE V-TWINS SUCK

Ok guys, I had a short in the power suply wire to th front brake light switch. So I just hooled it to battery pos . Now there is no prob. Just that brake lights work from front switch with the key off THANS AGAIN TO ALL.

Pay attention to what the asshole said
becuase they allways speak the truth