Main Breaker Tripping

[merlemac]

I need help! My main breaker (50A) is tripping, not the GFI breaker (50A). Yes, it has a dedicated circuit off the main panel.
First, I thought it was the GFI breaker and put in a new GFI breaker. That
wasn’t it. Main breaker still tripped when I turned on the spa.
Next I thought it was my heater and replaced it with a new heater assembly.
Nope, still tripping the main breaker
I tried to narrow the search by unplugging each component one at a time, including the heater, to see what component is tripping the main breaker. No luck. Nothing tripped the main breaker by itself.
If I run the main pump and heater at the same time, this is the only way to cause the main breaker to trip. Again, the GFI breaker (50A) does not trip.
I have no error messages on the panel. It’s a Gecko In.Ex-5
Is this the rare situation where I could have a bad main breaker? Is there anything else to try or it could be?

[Dr. Spa]

No, this isn't a rare situation where the main breaker is bad. It's probably bad main breaker.

Course you could continue with your trial and error of arbitrarily replacing things.

You could also put an amp meter on and make some tests to figure out what's actually bad.

[PreservedSwine]

I second the Doctor's sage advice. Additionally, check for signs of overheated, or burned wires/connections at the 50 Amp breaker that trips, as well as where the wires from the 50 Amp breaker connect at the subpanel that houses the 50 Amp GFCI breaker.

[joe645]

I have a similar problem. My Sensation Spa would turn on normally and run for about 10 minutes or so then kick the 50 GFI breaker. I thought something might be wrong with the spa but couldn't locate any signs of problems. I checked the GFI breaker and it smelled funny. One of the red wires (hot) was burned as was the screw holding it on the breaker. Also the breaker had a swelling on the side of where the wire connected. Those are not cheap breakers. I am going to presume that the breaker is the problem and replace it.