[Al Skierkiewicz]

This is picture of the #6 cutters we use. Please note the warning on the handle, Do not use on steel.
We also use a vise to crimp our terminals. And we solder every one. It requires a large iron tip but we use a 35 watt iron. It is technique I have taught to our students. If you cut one strand from a 7 strand cable, you have increased the series resistance significantly. Cut off three strands from a 19 strand cable and you are doing the same. Cut off two of the 7 strands and you have reduced the wire to a #8.
As to heating the main breaker, that is the way it works. It is a bi-metal device. It is not the magnetic type used in house power panels. If it was tripping due to external heating, then poor connections can cause that localized heating.