I've seen people use all kinds of wires to install 12v power inverters. I've even seen someone use light guage speaker wire! I couldn't believe it and I politely informed him why his wire selection was not the right choice.
When you are installing your power inverter keep in mind that you are running large amounts of electricity through the wires. There is a reason that your battery cables are heavy gauge wires. When you are moving a lot of power, heat builds up due the high resistance in the wire. Think of it like a straw. It's very hard to suck through a thin coffee stirring straw. Think of thin wires like the thin straw. Electricity will have a hard time getting through the thin wires. Chances are that they will get hot, melt the insulation off and short out.
Whenever I install a power inverter, I spend a couple of extra bucks and buy the really good stuff. I like to use 6 or 8 gauge welding lead wire. The insulation is thick and less likely to wear through or melt.
.
