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Chas: That's odd, out of all of the 110v spas I've sold I've only had 1 customer with issues with popping the breaker. Most outside outlets are dedicated, so why would you install another? I think Marquis tubs draw 12-14 amps with the heater/pump on low. One thing I always thought was weird, why doesn't Hotspring supply a plug in for the 110v spas they sell? A lot of manuf. supply the plug in with a GFI breaker at the end of the cord?
...The code requires that outdoor outlets be GFI-protected, and the same for bathroom outlets, so the cheap/easy way to do that is to put one GFI in a bathroom, and then just run the other outlets from there. So when you turn on the blowdryer, if the heat is on in your tub the breaker will trip - or certainly SHOULD trip...
. I live at an elevation of 8900. .