In anything but commercial the normal thing I have seen was the 50a 120/240 GFCI breaker feeding the spa, usually a skid pack and an in ground spa. In some of my wife's mini mansions they had the spa integrated with the pool and there might be a couple GFCI circuits feeding this. One for the pumps and one for the 5 ton heater. The valve farm in some of these combo units looks like the plumbing on the space shuttle with a computer running a half dozen (or more) Jandy 2440 valve actuators particularly if there is also a solar array.
I have also seen "listed" self contained units that I never understood how actually got listed. Things like low voltage control panels and sound systems right in the rim of the spa. I suppose they are compliant to 680.22(D) but I am not sure why. They seem to all have early end of life failures from water intrusion.
