Safe way to remove paint from ground wire

If the paint is in good condition, with no chips, peeling unsightly blemishes I would repaint. It would be a lot of work to get the pipes really clean. Any exposed thread at the fittings will be tough to strip You will need to scuff the old finish to promote adhesion. Pick a metal color. Rustoleum has colors like Bare cast iron, nickel, brass etc. You could accent the fittings with a contrasting color. Just be careful when working around the sprinkler heads.

I would try a Muriatic acid and water solution. I know the Acid will etch the Block just not sure how well it will remove the sani-tred. I would start with a 10% acid solution and work up from there. Usually I do this to floors prior to painting. If I need to make the surface rough for better bond for tile it works also. I have used mixtures up to 30% depending on how aggressive I want to etch the cement. You will need fresh air in a basement as the fumes can get quite strong. Remember to always add acid to water and use rubber gloves to protect your hands. All pool supply stores will carry Muriatic acid and most home improvement carry it. It is not that expensive for a gallon to give it a try.