Got one coming Friday- owner had circuit run and h.depot 50a gfi disco installed by someone else.He called me today after tub installers had been there;When the unit was energized it quick tripped the bkr.(several attempts)One of the crew must have a little elec. insight; owner said the guy found "something" wrong in the main(?)panel, and changed "something' AND drove ground rod at disco.Net result was delayed trip.I had them trip on leaky heaters; anyone shed any light on potential problems. What are the odds it's a bad gfi-disco?