Home power intermittently tripping

[devion]

Recently my RCCB keeps keeps tripping intermittently. It can happen between several hours to few days when a trip will occur. During the trips, no additional appliances were switched on or being used. There are times when it simply trips in middle of night when most appliances are not running.
There are also times when the trips can happen successively a few times in a minute but was able to recover after several resets.
So far am able to reset the RCCB all the time.

On few occasions, one of my MCBs also tripped & this helped me to suspect the issue could be isolated to one of my rooms. However in most cases only the RCCB trips, hopefully the occasional MCB tripping is not leading me to a wild goose chase.

With this, I had to switch off each devices in this room connected to the tripped MCB & monitor several days if trips been resolved.
Reading few blogs, MCB trips could be due to faulty appliance or overloading.
In this room, I have 3 PCs, 1 router & 3 handphone chargers plugged in into 2 socket outlets with 2 multiple sockets extension. I had this connection for several months w/o power trips which is why I am not suspecting overloading here.
In some instances of power trips during the nights, PCs & chargers are not in used, although power was not switched off for the chargers. Only the router is turned on all this time.
if faulty appliance, I would expect the trips would be almost immediate & not so intermittent.

Was hoping to find out any quick method to determine which of this is the cause of the intermittent trips other than isolating one each time & monitor several days.
Another suspect could be the RCCB itself although this would cost me to purchase a new one or engage a licensed electrician to fix it.

 

[Mike Johnson]

Even unplugging every appliance and plugging them back in one at a time may have also helped, just switching them off never does anything, except fool you.

 

[Electro-tech]

I hate to bang on, but an RCD test when i suggested it would have helped .

The obvious solution ! After all the tripping over that time the device may have become too sensitive & not latching properly

 

[devion]

RCD test, can elaborate more what is this? Can it done by my own or require license electrician?
Unfortunately, today my main RCCB tripped again, after 5 days!!! This time I managed to use my recent purchased GFCI power socket & then I plug my 2nd PC to this. Within minutes, the GFCI tripped w/o my mains tripping!!!
This GFCI socket actually tripped 2x when I turned on my 2nd PC connected to it, so I replace the power supply with a spare. Now am monitoring.
This is indeed very hard to determine with the longer intervals of a trip event but am subtly confident that am nearing a fix.

I did contact electricians & explained my issue, at least 2 of them stated that they cannot guarantee a fix but they can help narrow down the cause/s. They mentioned about mega ohm the circuit to check which I believed it is measuring the amount of leakage current in each circuit in my household.
Hopefully today's incident with the GFCI socket tripping on my 2nd PC is inferring the issue to be my PC, power supply or other components, this I might not know, at least I had the power supply replaced & monitor.
Very frustrating as it is very random & now becoming more sporadic & less frequent.
Am also hoping that the main RCCB is still fine, in case it gets much more sensitive to earth leakage after this many tripping...50x at least for now. I believed my RCCB is rated at 30mA, I googled the various RCCBs available out there, saw some which is rated at 100mA, not sure whether this is safe for household usage, which I thought can handle more higher leakage current appliances.

 

[DPG]

RCD test, can elaborate more what is this? Can it done by my own or require license electrician?
Unfortunately, today my main RCCB tripped again, after 5 days!!! This time I managed to use my recent purchased GFCI power socket & then I plug my 2nd PC to this. Within minutes, the GFCI tripped w/o my mains tripping!!!
This GFCI socket actually tripped 2x when I turned on my 2nd PC connected to it, so I replace the power supply with a spare. Now am monitoring.
This is indeed very hard to determine with the longer intervals of a trip event but am subtly confident that am nearing a fix.

I did contact electricians & explained my issue, at least 2 of them stated that they cannot guarantee a fix but they can help narrow down the cause/s. They mentioned about mega ohm the circuit to check which I believed it is measuring the amount of leakage current in each circuit in my household.
Hopefully today's incident with the GFCI socket tripping on my 2nd PC is inferring the issue to be my PC, power supply or other components, this I might not know, at least I had the power supply replaced & monitor.
Very frustrating as it is very random & now becoming more sporadic & less frequent.
Am also hoping that the main RCCB is still fine, in case it gets much more sensitive to earth leakage after this many tripping...50x at least for now.

A ramp test will determine at what amount of leakage the RCD trips at. It will need a proper tester to do this (either a dedicated RCD tester or a multi function tester)

 

[devion]

Likely my final update. It finally got down to the PC PSU power cord causing the trips, but it was really weird in how this came about. I was using my PC with a replaced PSU connected to a GFCI power plug for few days w/o issues. I then head off to a week vacation & off mains power to this PC.
When I returned from my vacation & powered on this PC, my RCCB tripped immediately. I was dumbfolded. I was able to repeat this again & so its now very consistent that my PC caused this trip, but a week ago I was using this w/o issue.
When I unplugged the PSU power cord from it, I did noticed the end of the cord to have a tiny bit of liquid on it....tried to smell it but nothing.
I found another power cord & plugged this into this PC & there was no trip. Next I simply plug the problem power cord w/o load to a power socket, the moment I turn on the power, my RCCB tripped.
I tried to use a multimeter to measure the 3 pins of this cord but I was not able to read any ohms between them.
Dunno how this could have occurred, especially when this power cord was used fine a week ago & after powering off & a week later, this same cord had a catastrophic failure. How puzzling is this....some degradation of the cables within this cord?
What was that tiny bit of liquid found at the ends where it connects to the PC PSU?
I will try to cut open the cable to check for internal cabling issues. Maybe around the ends, might have some cable kinks that resulted in internal damages.

 

[Lucien Nunes]

Thanks for the update!

Detachable appliance power cords vary in quality from excellent to nightmare, often with few visible differences to tell them apart as the bad ones usually have counterfeit approvals moulded in. They are often bundled with the appliance at a late stage by the vendor, and may not be of a quality that the OEM of the goods would approve. I have seen high-end professional media equipment costing $30k bundled with cords that did not meet the applicable regulations, because the global distribution warehouse purchased them separately to match the plug requirement of the destination country.

Problems found in defective and counterfeit cordsets include undersize conductors, aluminium instead of copper, out-of-spec plug pins, unapproved and non-sand-filled fuses, female contacts that are not correctly touchproof, reverse polarity, shoddy spot-welding and complete disconnects at the terminations, etc. etc. On this forum, we heard about a cord that was giving people shocks where the black plastic moulding of the connector body was partially conductive, presumably through contaminated plastic feedstock containing carbon being used in the moulding line. We have also seen a plug where the spot-weld tags were less than 1mm below the top surface of the plug and the slightest damage would allow them to punch through and be exposed.

Another cable manufacturing error that we saw causing intermittent faults was a mechanical splice, intended to draw a new length of conductor into the extruder, that had been allowed to run through and gotten into the finished cable, which cut through the adjacent core's insulation. Presumably they didn't even do a water bath test on the insulated core before making up the cable. I can imagine some constructional defect like this being responsible for your problems. It will be interesting if you are able to dissect it and find something definite.