Almost Burnt Down My Car, Why?

I have these neon wires in my car that are connected to my battery after going through a tiny box where you can turn them on and off.  I've had them hooked up without a fuse in my car for about a month and they've been fine, but yesterday I wanted to install a switch (lighted) so that I didnt have to reach back for the box all the time.  So I attached the ground lead of the switch to the wire that I used to ground the neon wires, then I cut the power wire to the neon wires (the power wire before it got to the box) and attached it to the power terminal o fthe switch, and then attached the ACC terminal of the switch to the the other cut end of the power wire.  When I attached the negative battery terminal back on, my wire from the neon wires that was hooked to my battery started smoking and burnt all the way to the switch.  Can anyone tell me what I did wrong, and why the wire would only burn after I attached the switch?  Also, what gauge fuse should I use for the neon wires?  I was using a variation of gauges of wire, but the wire that was to my battery was 18 gauge.  Thanks a lot, and any help that I can get is appreciated.-Andy

You hooked up your switch wrong. on the switch one wire goes to ground and 2 wires are hot. one that is from the batter before the switch and one after. it sounds like you had the ground on the switched side of the hot wire so hot went right to ground.

It sounds like you hooked the main power up to something that was a true ground, or you pinched the wire somewhere to ground. It would be a dead short and get real hot. Did you hook it up through a regular or lighted switch? Also you should have had that wire fused, it would have just popped the fuse instead of almost catching fire.Certified Security Specialist

Always check info with a digital multimeter.

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Yeah I know that I should have had the wire fused, but I guess that I was just being lazy and also didnt have a clue of the correct gauge fuse to use.  I used a lighted switch, and I think I know what happened now.  Some of the connections that I had were only temporary (I was going to solder them after I tested it), so the connections, especially on the switch were a bit iffy.  They may have touched and shorted out, but I don't really know much abot that stuff and how/why things short out.  Any info helps, and by the way do you guys know how big of a fuse I need? Thanks.   -Andy

you should use a fuse on any hot wire cause you will burn your sh*t to the ground. i'v seen it many times.Big Dave