Matt,
You are bang on. I argue thermo mag vs. MCP all the time - for reasons read on. Thanks for the reply, what I am looking for. A little more about this:
What the picture doesn't show is the line side of the breaker, just the load side. This 400A circuit had a line side connected by THHN type cable, the load side is DLO (diesel locomotive). All connections are torqued to spec on a 30 day PM. But when as the seasons pass, the THHN expands and contracts, the THHN moves around a lot in the connections, the DLO much less. The THHN has about 27 strands / conductor, the DLO has 1005. The stress on an aluminum mechanical connection by the THHN is tremendous. The problem has been solved because we put DLO on both sides.
I believe I know how buy cable, but also emphasize that MCP manufacturers understand our need for compression type fittings, and not mechanical lugs that simply mash down strands until they seat themselves loose through load and/or temperate variations.
?????
Side note: I couldn't deal with a duplex outlet for the life of me. I tend to tear apart dryers and vacuum cleaners and to figure out a way to make them three phase. Fear not, my house is legal.