Hi folks. I've been struggling with this one and havent found my answers yet by searching here.

This is a 4 year old spa that other than replacing the heater a year or so ago, has worked flawlessly.

Recently, it would trip the GFCI with no apparent pattern. Some times it would run for hours (overnight) and when I would go out in the morning it had tripped. I would reset the GFCI and it would run for a couple minutes and it would trip. The heater worked good (it would cool off and resetting would allow the spa to get back to tempeture). The pumps all work as well as the blower.

I disconnected the Ozonator thinking that that might be the problem and I though it fixed it but sure enough in a couple days it tripped again.

I pulled the GFCI out and checked all connection on the box for grins and tightened everything up real well and it ran for probably 48 hours before it tripped again.

Now it seems to trip after 20 seconds or so, so I've disconnected the heater and reset it. Everything is running as I'm typing.

I put my digital voltmeter across the heater lugs (disconnected) and I got a reading of 0.00 I then left one lead on the heater lug and put the other lead on the cylinder case of the heater and I get a reading of 0.34.

How do I determine if the heater is bad and can a heater be going bad and intermittently trip the GFCI before it completely shorts out??

Thanks very much everyone........john