On Sat, 15 Jul 2017 08:47:11 +0630, Lenny Jacobs
wrote:


As I have said earlier, I did ask an electrician about the tripping. He
just shrugged and said it's due to moisture. No need to fix it. Indeed,
during dry season, there is no problem even when all the four
problematic breaker are flipped up.

With that much fault current this is probably more than a little
moisture. I bet you have boxes filling up with water. I would start
with a visual inspection of all of your outdoor fixtures and junction
boxes. You might also have some splices underground that are not
waterproof. Without actually looking at your installation it is hard
to guess from half way around the planet. ;-)