Hard wired Surge Protector wire strippers?

Like the rest, a sharp knife is probably the best and easiest way. But, if possible, try not to score the wires. Not so much on #6 wire, but stranded smaller wires, if scored, tend to break off and shed a few strands, especially if in a flex situation. So what you end up with is a technically smaller wire. Have never seen it make enough difference to talk about, but just a bit of caution is better than a heavy-handed attack. Back in my days in fabrication on the space programs, a almost invisible nick could cost a good days work. Some of those inspectors were VERY picky!