By far the best connectors for main power are compression connectors like
these! If you use the correct compression tool, these connectors will never come apart. That means don't use the wire stripper/crimpers that come in the KOP. Go to an electrical supply house and get a set of hand crimpers designed for these larger connectors. Tools similar to
this will work, but a heavier tool like
this would work better. There are also battery powered, and hydraulic crimping tools which are the best, but very expensive. Yes, these tools can be a bit pricey, but you won't be disappointed.
Try finding a local electrical contractor who has one of these tools, I'm sure they'd be happy to press your connectors. Best of all, these compression connectors were legal by the 2006 rules!
