I have had three inch copper strips on my raised vegetable beds for two years now. They definitely help to slow the critters down.....I bought mine up at Peaceful Valley Farm Supply in Nevada City...their new catalog just came out and they can be reached at 916-272-4769.... They offer threesizes - 20' is $11.95 100' is $42.50 500' is $198.00 Based on what I've seen and what I've read, a copper wire would not do much good.....the repellant effect occurs when the slugs entire body is on the copper, ( A reaction between their secretion and the copper causes a shock.) Good luck