i have a 2003 used pacific spa 2 motors 240v balboa system heater is a 5.5kw heater. the gfi trips when i turn it on if i disconnect the heater the tub stays on. it isnt the element because i have 2 brand new ones the i put in and it runs for about 5 minutes then trips. after that i reset it and it trips immedittly. i did do a search on the forum but did not see the trouble that i am having. any help would be great thanks

wayne