Pick up one of these.

I tried several of these before I finally found one that worked well.

I've used that type and wasnt too fond. The self adjusting nature means that if the wire insulation is too tough, itll fail. Try this pair, it has specific gauges and I haven't messed up a strip since I got it. The depth gauge also works well. Capri Tools 20010 https://www.amazon.com/dp/B01018CVM0/ref=cm_sw_r_cp_apa_i_ljUyCbK123XFD

I haven't used it for mid wire strips yet, but I've got 3 split wires to do this week, so I'm about to find out if it works