Clariman wrote:
My main question is - should I be concerned about this circuit tripping?
Circuit board has 2 banks of circuit breaker switches. Each bank is protected by a master switch. From time to time one of the master ones trips. It happened this morning. What puzzled me is that no individual circuit breaker had also tripped. Should I be concerned that there is a problem somewhere? How do I identify what is causing it?
This happens in a holiday home that we rent out. It has happened with guests staying here and the agency who handles maintenance for us thinks it is caused by the PV panels on the roof when it rains. Is that likely?
The main switch is likely (although you should confirm this....) to have an earth-leakage trip built in to it.
It sounds like one of the sub-circuits is showing an earth-leakage problem at some point (and you mentioning that this might be happening during periods where rain is present is perhaps key here), which is then tripping the main switch, rather than the sub-circuit breaker.
This often happens with outside-light circuits, but obviously it could also be affected by any rain-facing equipment, which is likey to also include your PV kit.
Obviously the key priority should be to find out where the moisture is causing the problem and eliminate the issue. If you're able to 'reset' the master switch after a period of time, this suggests that the moisture is drying sufficiently to remove the earth-leakage issue, so this should give you some hope that a better seal somewhere, where the moisture is getting in, should be something you can achieve.
Are you able to inspect the outside wiring to all exposed items? It's likely that there will be termination-points where cables enter and leave the external items, and also possibly junction-boxes where internal cross-wiring occurs, where you may see signs of moisture if you were to open those places up.
If you do find signs of moisture, then you'll need to find a way to stop the ingress of water, which should help stop these nuisance trips. Please note that these inspections should obviously be carried out with the power off....
In the longer term, if you can't source the issue itself, then you can have a think about isolating some outside circuits to see if the nuisance-trips stop, especially over wet periods where you've seen them happen before. This may at least help identify the particular circuit causing the problem.
Another option then would be to change the breaker for that circuit for one which itself contained an earth-leakage trip, but the key thing here would be to ensure that the reaction time of the sub-circuit earth-leakage trip was quicker (they are graded in millisecond timings) than that of the main breaker, and at least then, if you were unable to solve the issue itself in the short term, it would mean that just the sub-circuit would then trip under the fault-conditions, rather than the whole board....
Note that around this time of year, whilst rain can obviously be an issue, these things are often also seen being caused by condensation, rather than direct water-ingress, so just something to keep in mind during your search for the problem-area.
Good luck with your investigations.
Cheers,
Itsallaguess