I am running the wire for my hot-tub, and I had a few questions.

1.) My electrician told me I needed Type SO 6/3 wire, and I don't understand what the Type SO means, and is it really needed? I am running it through my attic, and its going about 70ft.

2.) He gave me two options of either the Type SO cable, or get 4 THHW wires, and run them through the conduit. Is PVC conduit acceptable to run this through? and instead of getting 100ft of each color (rd,bk,wht, grn/ylw), can i just get 400ft of one, and mark the color myself? it seems to be cheaper to do that.

Anyways, I'm getting very tight financially, and just trying to figure out which way would be the most economical, but still safe way to install the wiring.

Thanks for your help