home depot wire for car alarm?

The guy at Home Depot said I could use their wiring for a car alarm install.  I am getting 10 and 18 gauge.  Is that wire ok to use?  If not why?

Depends what it is. Wire with a lot of strands of copper is better because it is more flexible. Single stranded wire can work, but it doesn't bend very well. You probably won't be adding much wire besides what comes with the alarm.

Depending on the alarm's make I always find excess wire I can use e.g. DEI with the green and violet wires for neg. and pos. door triggers. You will only use one of them so take the unused length to add to say the trunk trigger wire to extend it. I have a large bag in my car choc- bloc with odd cable lengths. The only reels I have are blue, green, black and red but I hardly ever need to use them. Mike is right NEVER use solid core in a car, it can break. probably a Mike, is there a conversion chart for cable sizes, wire gauge to the ISO system at a guess, 18 gauge is about 0.75mm but I'm not sure, I can do spanner sizes, AF to metric in my head but I can't work it out!

Thanks kreg357, I've pasted it as a file.