Is a disconnect required when not plug and cord connected?
Do the split-bolts have to be seperated?
When I splice anything larger than #10:
4-11/16 Square x 2-1/8" Deep boxes for #6, and layer my split-bolts with 2 layers of 50% wrap varnished cambrick, 2 layers 50% wrap of Scotch 130C, and 2 layers of 50% wrap Scotch 33. I trim the ends of wires square and as flush as possible after the split-bolt is tightened.
I've never had a "blow-out" with this method.
Once on a job with a journeyman, the cover of a 4x4 blew off when energized (480V) with the split-bolts insulated with Cheap Electrical tape only. His "fix" was to layer cardboard between the split-bolts and walls of the box after a few more wraps of tape on the burned spot.
I just stood there with a "deer in the headlights" look...