Most Spa's I have hooked up have air switches for controls on the motors and pumps. My understanding as far as the GFCI breaker it is made to trip not only on ground faults and shorts but monitor the unbalanced current on the ungrounded and grounded conductors not to ground. And therefore trip before reaching a theshold of 6 ma. This is not text book but the general idea. I hope others reply if not right.
