On Mon, 10 Jul 2017 22:44:27 +0630, Lenny Jacobs
wrote:

On 10/07/2017 10:46, wrote:
On Mon, 10 Jul 2017 07:58:16 +0630, 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.
If you have a full panel - say even 21 breakers - all 15 amp, all
loaded to 80%, you have a 252 amp draw - no branch breakers are
overloaded, yet you are 25% overloaded on a 200 amp main breker.


Theoretically possible but that's not the case here. Every year, when
the raining season comes and the main breaker is tripped, I can always
trace to the same sub-breakers that cause the problem and turn them
down. They are not tripped all at the same time but they are always the
same four breakers that have the problem.
Then replace the damned things, they are not doing their job. There
is NO WAY the main should kick before the branch circuit protection

I studied the breaker box and found that it's not like what I usually
saw in the US. It has a 75 A main breaker labelled Ground-First FL Main
(this is a two-story building). There are two 63 A breakers labelled
Ground FL Main and another two 63 A breakers labelled First FL main.
Looks like this is a three-tier system. It is the same 63A breaker that
is tripped during raining season.

Usually, there are only no more than 10 lights on, two full-height and a
half-height refrigerators constantly on (doesn't mean the compressors
are constantly running), and a ceiling fan, a water heater. That's it.
Seems to me there is absolutely no reason a breaker would trip with a
load like this. That's why I suspect the culprit is moisture or
underground cable getting short circuited due to rain. Now, two breakers
are turned down. During dry season, all breakers are up.

By the way, this is 220 V.


OK - Euro system. Different problems. No "load balance" issues. 2
"main breakers" in the building. One never trips. The other trips when
it is wet outside. You have external lighting circuits on that main.
You most likely have leakage in those 2 circuits, not enough to trip
the branch breakers, but enough to load the main heavily enough that
the rest of the loads, combined with the circuit leakage, overloads
the main. Find out what is on the circuits in question and get those
circuits checked and fixed - or permanently disconnected.