This is an interesting question, and it so happens my Caldera Niagara is being delivered on Monday & the electrician is scheduled to come on Wednesday.
I plan to fill the spa on Monday or Tuesday before the electrician comes to run the power & do the hook up. The owner’s manual states this:
“DO NOT CONNECT POWER TO AN EMPTY SPA. Power to the spa automatically activates critical components within the spa, such as controls, heater, circulation pump and other systems. If power is supplied to these components prior to the spa being filled, the components will be damaged, and this may result in a non-warranty component failure.”
I figured the electrician wouldn’t be able to actually test the power to the spa unless there’s water in it. I plan to ask my dealer to be sure.
I guess different spas have different procedures on this.