I have a 2002 Cal Spas hot tub
Genesis Control Panel (electronic controls)
Balboa 2100 control box
2"XL flow thru heater
GE 4hp dually motor/pumps

My problem: hot tub heats/circulates/runs fine on low speed.
On high speed, the breaker trips after about 1 second.

I have checked a number of items:

1)have let the spa sit without electricity overnight - no nothing is hot. still does it

2)have checked the pump/motor...is clear, rotates fine - though turning it is a little stiff

Seems to me it has to be one of:

1) a ground fault (by why only on higher speeds?) and could the fault be in something other than the motor?
2) something causing the motor to draw too much current
3) something wrong with my breaker (looks clean/good)

but i'm at a bit of a loss of how to diagnose further without just buying/trying...

One more fyi. the heater element failed last year - causing ground faults. was replaced, but no real usage of new element yet...not obvious related, but ???

thanks for your help

Sandy

Well, the first two of your suggested diagnostic thoughts are most correct. Since it's happening so fast, (lets say the spa sits for a while, you power it up and then try this and it trips within a second... I wouldn't suspect the breaker).

Since low and high speed use a different set of pump windings, it is entirely possible the motor can be causing this problem. If you try disconnecting the motor and then sequence the control from low to high and the gfci doesn't trip (you'll have to do this quickly before you get a flo error), then I'd replace the motor.