This is Turtle.

now before i start telling this even. i did not do it or will i ever do
it. With this clear i will speak.

i was looking a air handler for a HVAC customer and he run the electric
service hisself to the air handler and when he got to the A/H with the
wire was about 6 feet short to get there. So he just got another piece
of wire and SOLIDERED the # 6 -2 with ground Wire set together to
complete the circuit to the A/H. I know this is illegal here in out
local code but i can't find it in the NEC for not having a new copy.

So how bad is solidering # 6 copper wire for high amp draw in a slice
joint?

TURTLE