GFCI Dropping When Load Removed

[mbg]

We have had a hot tub (guess they call them spas now) since around 2009 or 2010. I had to replace the GFCI breakers in 2011 do to a wire being slightly loose in the main panel - my error, found out later these cables take a set so need to be moved around a bit after installation and re-tightened a few times.

The sub-panel for the tub has two 240V GFCI breakers. A 30A for heater/pumps and 20A that is for lights and electronics.

Here is my strange problem (just started few days ago). Once in a while when you turn "OFF" a pump/jet or when a cleaning cycle ends the 30A GFCI trips. These go for around $100+ so don't want to just buy one and find it's something else. It was tripping almost every time I turned off the small pump that performs the cleaning cycle. I opened the sub-panel which is outside and it had quite a few cobwebs and spider webs. I cleaned them out and no issues for two days. Now getting intermittent trips. Was thinking next step is to open the panel on the tub and blow it out - it has to have the same cobwebs and spider webs as the subpanel. (Heard it was possible for these webs to trick the GFCI.)

If I Google the issue seems everyone has issues when turning devices ON not OFF like me. This makes me think it has something to do with the 30A GFCI breaker - the GFCI function of it.

Appreciate help troubleshooting this.

Thanks
Mike

[Phil Thien]

Maybe some solenoid or switch or other sort of device is arcing when turning off? Sort of like unplugging a vacuum cleaner when it is running?

I guess the obvious test is to swap the tripping breaker and see if the new one trips? You should then know if you fixed it, or if the problem lies further?

[museumguy]

Might be far fetched but I had a small issue with mine. Eventually, it stopped working. I had someone look at it and it was suggested that the circuit board was toast. I thought for a few days and started with the easiest part to replace. Turns out it was a $2 fuse that had blown. Like I said, far fetched.