Appreciate, I disconnect lighting one by one and use the meter test neutral and earth on DB right?

This post has been edited by FyChai: Aug 16 2024, 01:42 AM

to visualise better some questions.

how old your wiring
what type of lighting on this loop ? fluorescent 4 feet? LED downlights or the leds bulb screw on type,
the LED is it 1 driver for multiple leds or ?
how many switches on this loop , LEDs.

the rccb trip can happen when none /light, fan is ON , ?
is the fan ON at that time ?
tryin to understand situation when rccb trip timing

example fan have coils . when in use heats get hot and the coils leak .... then trip.
this is my main suspect .

you need a test pen .
and a rubber gloves too .

there are also multimeter about 100 RM more solid if budget allows . check only sanwa and uni T brands.


This post has been edited by Momo33: Aug 16 2024, 06:49 AM

Wire around 15 years, but just use for 1 year. The house empty 10+ years.
2 round ceiling light, 3 normal light with bulb, 5 LED downlight.
2 switch for 2 round ceiling light, 3 switch for 3 light bulb, 2 switch for 5 LED downlight, 1 switch for 1 fan

I tried off all of them, and also off the MCB, RCCB still trip within 5 minutes to half a day. I try to switch on fan for hours, didnt trip, but the RCCB straight away trip when i off the fan, but only once.

The RCCB never trip after I disconnect the neutral cable from DB box.

all the lights point is in the hall or go also outside car park or ? if outside check water leaks/ wet and all the power connect

all the lights neutral wire return to the DB on 1 wire ?

am thinkin how to check and if can break up the circuit . or know how the neutral wiring loop goes to the points.


the round ceiling light is fluorescent round ? if yes open check any loose/ bare contacts . try to disconnect both out from the loop at the power connect to the light . . check if rccb still trip

is any part of the wiring under a false ceiling ?

the neutral wire from DB goes point A and continues to point B and point C etc..
means at the power point connect / is a 3 point carrying L N E , you will see 2 wire connect together cos to continue the loop .

the idea is to break the neutral loop , by disconnecting them . mean 1 wire is connect , the other hang free. hence you break the neutral loop to exclude light further down the loop . for troubleshooting purpose .

I tried to DIY but I found the cable looping and i unable to buy UniT multimeter, so I didnt touch it and ask wireman for troubleshooting.

Wireman found out there are 3 neutral cable looping at fan and one of it ohm lower than 0.1, so he disconnect the faulty neutral wire from the fan and ON RCCB and Main MCB. The RCCB works, but trip after couple of minutes, and he pull ON the RCCB again,.

Few of my applicants burned out with sound "boom" immediatrly when he ON the RCCB. Lots of socket surge after that, and the surge issue solved after he install back the neutral cable at fan and wireman said is it because of thunder, not his fault. Since its raining at that time...

Its that really? Need you guys advise please. Appreciate.

This post has been edited by FyChai: Aug 23 2024, 02:06 AM

Wireman found out there are 3 neutral cable looping at fan and one of it ohm lower than 0.1, so he disconnect the faulty neutral wire from the fan and ON RCCB and Main MCB. The RCCB works, but trip after couple of minutes, and he pull ON the RCCB again,.
>> its possible there are other wiring at higher that normal leakage . your rccb 30 mA too sensitive . house wiring is old and leak higher. Last time the standard "Old house" use 100mA .rccb.

Few of my applicants burned out with sound "boom" immediately when he ON the RCCB.
>> this i not sure why ..cos should not happen .
put ON rccb cause a small surge but appliances can handle this.

your appliance blowup IMMEDIATELY at rccb put ON or after some time ??

he install back the neutral cable at fan
>> the faulty N wire replace or ?

The RCCB trip is a sign , it mean there is leakage, it protect my appliance and cable, and I had use 30mA for year, no issue at all.
The appliances didnt burned out when RCCB first trip, its only burned when wireman push ON the RCCB after trip. Old house doesnt mean using old appliances, 30mA is definitely works. Singapore old house also use 30mA

I had checked with other PW4 wireman, if there is looping 3 cable on neutral, it mean more than 1 MCB sharing the neutral, simply disconnect neutral but didn't disconnect the live cable will cause short circuit and burn. Wireman should also check and disconnect the live cable.


I heard 3 sounds of explosion immediately when he ON the RCCB after trip.
The short circuit issue solved when he connect back the faulty neutral cable, didnt replace with new cable.

This post has been edited by FyChai: Aug 23 2024, 12:24 PM

the main purpose of rccb is to protect human . Not appliance .
rccb do not have over current protection . you have MCB for this.

The Malaysian Tenaga recommendation is 100mA for main DB , 30mA for sockets , 10mA for water heater.
new house developer will put 100mA .
yes can use 30mA but the risk is more trips when the wiring get old and degrade. this depend also if the wiring is first grade cable or cheap one.

""I had checked with other PW4 wireman, if there is looping 3 cable on neutral, it mean more than 1 MCB sharing the neutral, simply disconnect neutral but didn't disconnect the live cable will cause short circuit and burn. Wireman should also check and disconnect the live cable.""
this explain above i find no logic. . if remove 1 neutral wire that part circuit will not function/ cos the wire loop is not close complete and current cannot flow. means that bulb not work .
its shuld not trip rccb. or blow any
example if 1 wire for your bulb accident get loose/ or broke that light dont work , and rccb will not trip . right.

my guess is he not connect/ tight 1 connection cause sparking , cause trip rccb .
my guess .

Erm, what is the point we discuss RCCB on this matter? Its really trip after the neutral cable disconnect, and I use it for year, never trip even thunderstorm, the only disadvantages is expensive.

I'm not proffesional on eletrical, but the facts is it trip after the faulty neutral cable disconnect, and whole house short circuit with few appliances, bulbs, adapter burned. Wireman take hours to troubleshoot, issue solve after he connect back the neutral cable.

Base on I check on chatgpt, the answer also meet what the PW4 wireman said :

ChatGPT
No, you should not disconnect the neutral wire while leaving the live and earth wires connected, especially with the current on. This is dangerous for several reasons:

Electrical Shock Hazard: Disconnecting the neutral while the live wire is still connected can create a dangerous situation where the exposed wires or connected devices may still carry live electricity. This increases the risk of electrical shock.

Potential Damage to Equipment: If the fan or any other electrical device is designed to use both the live and neutral wires, disconnecting the neutral can cause improper operation or even damage the equipment.

Fire Risk: Without a proper return path (neutral), the electrical system may behave unpredictably, potentially causing overheating, short circuits, or fires.




I'm not going to argue anything, just want to know the truth and prevent it happen again in future. Anyone with relevant knowledge or experience can share info with me please, Appreciate.

1. The fact the 'electrician' quick to blame the lightning and reconnect back the faulty neutral cable shows he himself not sure what he was doing.

2. Is your electric supply 3 phase? If yes, then that explain the exploding appliances. There are circuits from different phase using the same neutral cable. If the appliances connected to that neutral cable (now disconnected) are left on, it will ended up the appliance being connected phase to phase 400V instead of 230V. Normally nobody will even think of shortcut share neutral in 3 phase, but occasionally there are daring idiots who think it is safe to do so as long as it is in the same phase. But that circuit might relocated to different phase later on causing this issue. You will have to untangle this shared neutral mess as the neutral cable might be overloaded without tripping the MCB.

Cannot disconnect neutral. Sure boom because of phase to phase is 415V.
Since the point of issue is too many neutrals tapping illegally into the fan neutral, what are those other two circuits powering? Does running a "patch cable" (exposed new cable) back to DB neutral busbar keep the power online steady?

Did wireman check that those 3 neutrals are actual neutrals and not swapped? (there is such possibility in hack wiring that the live and neutral are swapped)

My 1995 era house is on 3phase 30mA single RCD, seldom trip.

However, there is risk of brittle/loose contact in older wiring (if never move is ok) but once re-bent/reshaped to accommodate DB box replacement terus no power for that circuit - because the copper already patah inside.

Yes, my house is 3 phase, and the 3 looping neutral cable is ori from developer, lol...

I am not sure did other phase using same neutral cable also, but upstair water heater, extension cable and light bulbs burned also. Losses thousands of ringgit, so pain..

This post has been edited by FyChai: Aug 23 2024, 09:46 PM

I am not sure is the neutral cables running patch cable back to DB.
Wireman has check other 2 neutral cable with multimeter with 500v, Ohm result show OL. The fan at living hall, faulty cable connect to other light at living hall, while another 2 functional neutral connect to yard and car porch lighting.