I just upgraded my old hot tub with a new PID controller. My tub is a 240v 60a service. My PID required no more than 120 volts so I took it from one hot and what I thght was the neutral bus. Looking closer at the schematic, it appears I may have conncted to a ground bus. My tub has 2 hots and a white wire which terminates to the neutral bus in my main panel (I don't have a seperate ground bus in the main panel). My tub also has a ground rod near it which is bonded to the bus inside the tubs panel that I connected to. Both the bus in the tub panel and the ground rod are bonded to a stray current collector in the water. As you may have guessed, my tub is not equipped with a gfi as it was not code at the time. I have used the tub several times and haven't had a problem, but the more I look at the schematic the more I think what I added wasn't done right???