Warning: You must be a qualitied electrician and or service technician to perform diagnosing or serial injury or death can result: High voltage components are in use. If the spa was recently installed, the most common reason the GFCI would trip is the Load Neutral (white wire) between the spa and GFCI which must be connected to the Load Neutral port in the GFCI breaker. If the neutral wire is connected to the neutral busbar, the breaker will trip during startup. The neutral connection must not have contact to the ground on the load side of the breaker or it will trip. If the spa is not tripping immediately upon startup, a process of elimination should be used to identify the problem. Disconnect one component at a time from the control board and try restarting the spa. If the breaker trips, reconnect the component then try again by disconnecting a different component. Continue repeating this process until the breaker does not trip. Components include pumps, heaters, lights, stereos, ozone, etc. If the breaker does not trip after disconnecting the component, then the disconnected component is the source of the problem. Once you have determined which component is at fault, replace the component. If you have not found the source of the problem after disconnecting each spa component individually, disconnect all components from the control board and try starting the spa. If the breaker still trips, a certified electrician will need to inspect the breaker and wiring.