I would say 10-12 feet. I assume you're talking about the power wire??? What size of wire are you using??? I would recommend at least 4 gauge, 0 gauge might be somewhat of a pain to run, since it's so thick. How big of an alternator are you getting, and what brand??? I bought a 200 amp from Motor City Reman for my truck about 4 years ago, and it hasn't failed me yet. I'm also planning to upgrade my alternator on my LS, I might go with db electrical, a bit cheaper.