I just cracked open my copy of the NEC (National Electrical Code) Book and checked into hot tub and spa requirements. I should hope you would have known intuitively that everything needs to run through GFIs (Ground Fault Interrupters). Also, all wiring needs to be in conduit, and there are specific burial requirements. The spa and hot tub subsection is about 3 pages, the entire section (which also covers swimming pools and fountains) is about 21 pages.
I would bet a 6-pack that a hot tub install would require pulling a permit and passing inspection in most municipalities.
I would be comfortable doing this myself if I were interested in having a hot tub. It isn't rocket science, but there are very specific requirements.