The spa keeps tripping the household fuse breaker. What do I do?

Test whether the GFCI/RCD/PRCD is faulty or not, following the instructions in the manual. If the GFCI/RCD/PRCD is good, then the tripping might be an indication that the circuit is overloaded. You should either remove all other appliances plugged into that circuit or use another circuit dedicated only to the SPA. If this does not correct the tripping problem contact a qualified electrician.