On Mon, 10 Jul 2017 22:54:12 +0630, Lenny Jacobs
wrote:

On 10/07/2017 18:03, Terry Coombs wrote:
On 7/9/2017 8:28 PM, Lenny Jacobs wrote:
When a breaker is tripped, it's always the main breaker, not the
individual breaker. Shouldn't the individual breaker be tripped first?

This is troublesome because I then have to turn off all individual
breakers with the main breaker on and flip each breaker to see which
one causes the trouble.

That ain't supposed to happen . When an individual circuit overloads
that breaker and only that breaker is supposed to trip . Either you have
a defective main or the wrong amp rating . Or maybe you've got way too
big breakers on the individual circuits . Most mains are 100 or 200 amps
, 30 or 40 amp breakers for stoves/water heaters/dryers , 20 amp for
most outlet circuits and 15's for lighting .

--

Snag


That is what I'd expect but that's not what is happening here.

I have 10 lights on, a water heater on, three refrigerators on, a
ceiling fan on. How can these trip a 63A (220 V) breaker? It must be
short circuit of some sort. But why is a main breaker tripped, instead
of a sub breaker?

Because it is an RCD. (30ma GFCI for you Americans)
Fix your water infiltration problem on the outside circuit.