Look, I know it’s a pain in the butt, but if you are going to tap into a wire, this is the right way to do it. Don’t use a Scotch-lock. Use a quality wire stripper and cut the insulation—and only the insulation—about an inch back on the wire. See the cuts? Then use a utility knife to cut the inch of insulation away. Be careful to not cut the original wire with the either the knife or the strippers.