"Lets say I'm going to install a hot tub indoors on a concrete slab. How do I get the wiring across the floor to the spa. A piece of SO seems like the best method but doesn't SO have to be in a cord set or can it hard wired with SO??"
I'm not an electrician, and i don't know all the detail of the code, such as putting a cord on a spa, but it just sounds like a terrible idea.
to get power to the spa in the center of a contrete slab, you could rent (or hire someone with) a power breaker and chip out a grove in the floor, put a pipe in in and then fill it back up with concrete.
another option, since you say it is indoors would be to build a false pillar right next to the spa. the wiring could go up the center of the pillar and then go through the ceiling. you could mount hooks on the pillar for hanging towels and clothing for spa users.
For the post about plugging in the spa to a dryer outlet when you want to use it- Just tell the homeowner that besides the fact that it violates code, it will be very inconvenient. When you want to use the spa, you will have to plug it in a couple hours before you plan to use it so it can warm up. also, spas get really nasty if the water is not circulated frequently. if it was left unplugged for a 5 days or so, it will get NASTY no matter how many chemicals you put in it.
