have 0 gauge power wire, but don't have a ground wire! can I use the power wire as a ground wire if I cut a piece off?
Sure, wire is wire. Sometimes you can have noise problems when the grounding wire is too small, but you're talking about 0 gauge so definitely not an issue! This is all provided that you have a way to connect a 0 gauge wire to the equipment you're talking about. Most won't accept that large of grounding wire because it's overboard on size.
Sure! Normally a ground wire is green so you can wrap a little green tape around the ends. Make sure you connect it to a bright metal spot on the frame of the car or go directly to the negative pole of the battery.
The only difference between ground wire and power wire is the color of the jacket. Otherwise it's identical. If you have leftover power wire, go ahead and use it for the ground. Just wrap some tape around the end so you can tell it from the power wire if you need to disconnect and re-connect the amp.
0 gauge? you probably have 14 awg, and yes, you can cut off a piece and use it as the ground strap, but you would be better off to use an actual ground wire, because later on if someone goes to work on that outlet they could miswire the new one. EDIT whoops, just saw the category, i saw this question on the main page, i was thinking home AC...not car audio, my bad.
Eric? WTF are you talking about? 14 gauge is for speakers! Or a 20 watt amp, haha. Yes, they make 0 gauge wire. It doesnt matter what color the coating is, wire is wire! If you thought otherwise... well, I wont say it. Also, your question should have more info about what you are trying to do, etc. And its not a good idea to run a ground cable all the way back to the battery, hence why all amp manuals say use an 18 inch ground wire or shorter! If you have to use sandpaper to sand some metal and create bare metal, do it.
