Instructions to electrician about dedicated line

If you can afford it, use BX and make it 10 ga.

Run 220 vac if you can to iso transformers for step down.

OR, use a single large ISO tranny in the basement to provide
local power... isolate each line with an RFI/EMI filter.

Put a big ass GROUND wire on your main service, and use
a real copper ground rod, have the earth prepared properly too.

MORE is always better in AC power.

Sure, Sean, that's pretty good in principle - but you have to think about what happens to the grounds too...

Also, are you saying multiple 240vac lines, or 120vac lines?
One of the advantages of the 240-->120 stepdown is that it makes for a way stiffer line in general.

I'd be worried about voltage drops over multiple lines being different, and causing a ground problem on a 120v-->120v iso set up. With 240vac you have two hots and a dedicated ground there... dunno, I haven't thought this through all the way...