Foglight harness burns up

[NeroCB7]

Heu ci well I recently got some fogs from a friend and well it was just he plain fogs no harness so I bought one from autozone I wired everything up and it worked for a while like a week one day I turned them off and my dash got all smoky I turned off the fogs and checked under the hood only the primary wire was fried up(the one that connects to the battery) does anyone know why it did this. Do I need a thicker wire please help

 

[j13]

The Hot wire touched the shell of the car, and shorted out.

Next time, splice the Hot Wire, solder a 25A fuse inline with the Hot Wire, and wrap the whole wire up with electrical tape a few times.

Or you can go to any car alarm/audio shop and get a sleeve, for the Hot Wire so it can't wear off the wire insulation and short out.