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.

 

[devion]

I managed to locate the defrost heater unit at the freezer coil area, I simply terminated one of the wires & electrically wrapped it.
Let's hope this works.

 

[devion]

I managed to locate the defrost heater unit at the freezer coil area, I simply terminated one of the wires & electrically wrapped it.
Let's hope this works.

Update, after terminating one of the defrost heater wires, my trips became more frequent. It is now every 3-4hrs compared to previous 12hrs. This is very odd....desperate to get the new fridge in which is 4 days time. My fridge I believed is auto defrost, dun see a timer circuit there, not so sure whether it is now triggering more regular defrost cycles...

 

[suffolkspark]

Update, after terminating one of the defrost heater wires, my trips became more frequent. It is now every 3-4hrs compared to previous 12hrs. This is very odd....desperate to get the new fridge in which is 4 days time. My fridge I believed is auto defrost, dun see a timer circuit there, not so sure whether it is now triggering more regular defrost cycles...

You probably disconnected the Neutral. You need both cables off the element, and terminated in something safer than tape, can you trace them back to a pcb and unplug?

 

[devion]

You probably disconnected the Neutral. You need both cables off the element, and terminated in something safer than tape, can you trace them back to a pcb and unplug?

Today I proceed to the circuit board & unplug the cables to the defrost heaters. Hope it works. Unfortunately, when I was doing this with the fridge powered off but the power plug is still plugged inside the socket, my main breaker trip!!! OMG, hopefully its the fridge & nothing else. All this while am suspecting the fridge......
If its not the fridge, my only suspect is the breaker itself....but the trips frequency is so random, sometimes with a pattern of ~12hrs apart & just yesterday, was very frequent, ~3-4hrs apart. The latest trip event 2x, was only 1/2 hr apart.
Really a mystery to solve if its not the fridge...maybe the RCCB has deteriorated after so many trips...>50 times since abt a week ago.

I contacted one of electrical company, after I told them its random & unknown root cause, he stated cannot engage them because they need the trip to occur when at the location.
Am sure more qualified electrician will be able to conduct some diagnosis of my household circuit to narrow down exact cause of the random trips.
let's see if disconnecting the defrost heater circuit will work. fingers crossed. At my wits end now, have to hunt down a good qualified electrician to remedy my random trips.

 

[suffolkspark]

Today I proceed to the circuit board & unplug the cables to the defrost heaters. Hope it works. Unfortunately, when I was doing this disconnection, I powered off the fridge with the power plug is still plugged in, my main breaker trip!!! OMG, hopefully its the fridge & nothing else.
If its not the fridge, my only suspect is the breaker itself....but the trips frequency is so random, sometimes with a pattern of ~12hrs apart & just yesterday, was very frequent, ~3-4hrs apart. The latest trip event 2x, was 1/2 hr apart.
Really a mystery to solve if its not the fridge...maybe the RCCB has deteriorated after so many trips...>50 times since abt a week ago.

I contacted one of electrical company, after I told them its random & unknown root cause, he stated cannot engage them because they need the trip to occur when at the location.
Am sure more qualified electrician will be able to conduct some diagnosis of my household circuit to narrow down exact cause of the random trips.
let's see if disconnecting the defrost heater circuit will work. fingers crossed. At my wits end now, have to hunt down a good qualified electrician to remedy my random trips.

Unplug things when your playing with them.

 

[DPG]

Did you say you had had your RCD tested?

 

[devion]

Update - Been more than 10hrs with no trips, I conclude it is the fridge defrost heater causing the random trips. Ytd when I terminated one of the wires to the heater unit, I actually worsen the condition & experienced more frequent trips of 3-4hrs interval vs previous 12hrs. Read the manual of my fridge & it did state auto defrost every 4 hrs.
After disconnecting the defrost connection from the control board, the entire defrost heater is now terminated from the controls & power.
Thanks all to have provided feedbacks for my past 1 week plus ordeal.
Random power trips in middle of night w/o additional loads, trips in specific intervals of time, good lesson learnt here of what is the likely cause for such predictable patterns on trips. The one thing that confuses me was my bedroom MCB tripped occasionally & made me run a wild goose chase to start isolating devices from my bedroom. Funny that kitchen MCB did not trip where my fridge was.

 

[DPG]

I'm still intrigued by that bedroom MCB tripping.

 

[devion]

I'm still intrigued by that bedroom MCB tripping.

I spoke too soon, tripped again at the 11th hour. Its frustrating now. Guess will have to engage professional service to investigate, probably wait after my new fridge arrives in 4 days time. Sigh...
One electrical company provided me standard package for basic checks, troubleshoot live out-going, circuit breaker trip/function test, short circuit test & water heater connections, additional charges if need to further isolate the root cause.

 

[DPG]

Yeah definitely need to get some testing done. Keep us posted.

 

[devion]

Update - fridge was replaced & past 2 days no more random trips. Fridge was the cause but maybe not e defrost heater unit since I disconnected it from main circuit board, or maybe its still connected somewhere? Should have terminate e other end of the heater to confirm. Another interesting finding was even when fridge power is shutoff, it can still trip with the power cable still plugged in.
Suspect some residual current was still leaking after just turning off the fridge during e trip occurrence.
Lastly as in why my other MCB to bedroom was occasionally tripping, no idea on this. However this MCB is just beside the MCB connected to my kitchen where fridge was. Whether due to some kind of interference or something, it trips it. This one really blew me to a wild goose chase & doubting the fridge to be the culprit in the beginning stages of the frequent trips.

 

[Mike Johnson]

You need to unplug the fridge so it is totally isolated from your power, switching it off does not isolate it.

 

[DPG]

And did the RCD get tested?

 

[devion]

Wanted to update since my last one. After 3 days of no trips, it tripped again which concluded it was not the fridge. I continued to isolate individual devices in my room that had that occasional MCB trip during the frequent RCD trips, until one of my PC 750W power supply encountered an issue that my PC was able to power up & unable to boot up. After removing this PC out, no more trips observed for more than a week. Indeed it was one of my devices in the room causing this intermittent RCD trips.
Googling about earth leakage current causing trips, understood that it is the accumulative of leakage current of each devices that will cause the RCD to trip if it exceeds the limit. During my meddling with the fridge defrost heater, it probably caused more leakage current in my home circuit which then incur more trips & made me to suspect to be the fridge.
The lesson learnt here is that when isolating each device, need to unplug the cable from the power socket, the rogue PC that had been shutdown during times of trips made me not to suspect it to be the cause.
I was wrong about this.
A quicker method to check for high earth leakage current from each device is to use a leakage current meter & probe it with the live n
neutral wires of the device, & if the cable has an earth together with the live and neutral cables, need to exclude that from the measurement.
Saved some money of not calling an electrician to check. The PC power supply was RMA to the vendor as it is still under warranty.

 

[DPG]

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