Old MCB and RCCB Don’t Trip in Ampang House
Many Malaysian homeowners believe that as long as their circuit breakers can still “turn on and off,” everything is fine. Unfortunately, that’s one of the most common misconceptions in electrical safety. Recently, we received a call from a customer in Ampang who wanted to install an earthing system for his home, but refused to replace his very old MCB, RCCB, and main switch, saying, “No problem, still can use.”
This real-life case highlights an important issue: installing an earthing system without upgrading old protection devices can make the system ineffective and even dangerous. Let’s explore what happened, why it matters, and what every homeowner should know before investing in any electrical upgrade.
Old Electrical Components (ELCB/ MCB) Still in Use
During our site visit, we found that the customer’s main distribution board (DB) was equipped with the following components:
- NNE 63A 100mA RCD (Residual Current Device)
- ABB LSF 63 (1P + N, 63A)
- NNE brand MCBs (6A for lights, 16A for socket outlets)
And his sub DB was using:
- NES 63A main switch
- NES 63A 2-pole RCCB
- NNE brand MCBs (6A for lights, 16A for socket outlets)
At first glance, everything looked “normal.” There were no burn marks and the switches could still move up and down. But the real concern was their age, as most of these components were more than 30 years old. Upon testing, we also found that some MCBs did not trip at all, even under fault simulation, which means they no longer provide any real protection.
When we advised the homeowner to replace them before doing the earthing system installation, he declined, saying everything was “still working.” This mindset is risky because what you see on the surface doesn’t reveal what’s happening inside the breaker. Actually these brands are actually very well-known and of good quality; you just need to replace them with new units of the same model.
Why Old MCBs, RCCBs and Main Switches Are NOT Safe
Electrical protection devices are not designed to last forever. Just like car brakes or seatbelts, their performance declines with age and use. Inside every MCB (Miniature Circuit Breaker) or RCCB (Residual Current Circuit Breaker) are mechanical parts, springs and electrical contacts that gradually weaken, corrode, or lose tension over time.
Here’s what can happen with old or poor-quality circuit protection components:
1. Delayed Tripping
When a short circuit or overload occurs, a healthy MCB should trip instantly to protect the wiring. Old breakers, however, may react slower or not trip at all, allowing dangerous heat buildup inside cables.
2. Overheating and Melted Connections
Loose terminals or corroded contacts inside the MCB or main switch create resistance, causing excessive heat. This can melt insulation, damage terminals or even ignite nearby wiring.
3. RCCB Not Responding
RCCBs are designed to detect small earth leakages (as low as 30mA) and disconnect the circuit to prevent electric shock. When the internal mechanism is aged or rusted, it may fail to trip even when a leakage occurs.
4. Higher Fire and Shock Risk
Aged devices combined with poor earthing or moisture exposure, especially during rain, create a high risk of DB trips, sparking, or electric shock incidents.
So, while the switches may “still work,” their protection function may already be compromised, and that’s the real danger.
The Role of Earthing in Electrical Safety
Earthing or grounding, provides a low-resistance path for electrical faults to safely flow into the ground instead of through people or appliances. It protects both lives and property.
However, a good earthing system installation is only effective when paired with working MCBs, RCCBs, and main switches. These devices must detect faults and disconnect the supply immediately. Without them, the current will still flow through the circuit even when there’s a fault, making the earthing system practically useless.
Think of it this way:
Earthing = Safety path
MCB/RCCB = Safety gatekeeper
Both must work together for complete protection.
If your breaker fails to trip, even a well-installed earthing system cannot save you from a shock or fire.
The Right Setup for a Safe Home Electrical System
For modern Malaysian homes, a safe and compliant electrical setup should include:
- Main Switch: To isolate the entire electrical system in case of emergency.
- RCCB (Residual Current Circuit Breaker): Detects earth leakage currents and cuts off supply within milliseconds. Recommended sensitivity is 30mA for household protection.
- MCB (Miniature Circuit Breaker): Protects against short circuits and overloads. Typical ratings are 6A for lighting and 16A or 20A for socket outlets.
- Surge Protection Device (SPD): Protects against lightning surges or sudden voltage spikes.
- Proper Earthing System Installation: Includes earth electrode, earth cable, and testing to ensure resistance below safe limits.
If any of these are outdated or damaged, upgrading them before installing new wiring or earthing is essential.
Why Homeowners Resist Replacing Old Circuit Breakers
It’s common for homeowners to hesitate when told to replace their MCBs or RCCBs. Some think it’s unnecessary, while others see it as an additional cost. But the truth is, MCBs and RCCBs are not designed to last forever.
Most devices have a lifespan of 20 years, depending on usage and environmental factors. Malaysia’s humidity, dust and temperature fluctuations accelerate wear and corrosion. So even if the switch still “clicks,” it might not trip properly under fault conditions.
Just like you wouldn’t drive with worn-out brakes, you shouldn’t rely on aged electrical components to protect your home.
Common Signs You Should Replace Your MCB or RCCB
If you notice any of the following, it’s time to call a professional wireman for inspection:
- Frequent or unexplained DB trips
- Burn marks or melting near switches
- Loose or cracked terminals
- RCCB test button doesn’t trip
- Warm or buzzing MCBs
- Appliances get shocked or “tingling” feeling when touched
- Electrical trip during rain or thunderstorm
Ignoring these signs could lead to severe consequences like fire hazards or electric shock.
Why Professional Electrical Inspection Matters
A professional wireman doesn’t just “look” at your DB. We test it. Before installing a new earthing system, our inspection includes:
- Tightness check on all DB wiring
- Insulation resistance testing using a megger
- Loop impedance testing to measure fault current path
- Trip timing test for RCCB
- Earth resistance measurement to ensure proper grounding
These tests confirm that your protective system works correctly. If we detect weaknesses in old components, replacing them is the only way to ensure the new earthing system performs as designed.
Recommended Electrical Brands and Protection Setup
For reliable protection, we recommend high-quality components such as:
- MCBs: Himel, ABB, Hager, Scheneider or EPS
- RCCBs: 30mA sensitivity (for socket circuits), 100mA for sub-main protection
- Main Switch: Durable, corrosion-free, with tight connections
- Earthing system: Proper copper earth rod, 4mm or 6mm green/yellow cable and earth resistance below 10 ohms
A small investment in quality parts greatly reduces the risk of DB trips, shocks or electrical fires.
The Ampang Case: What We Advised
After explaining the risks, we advised the homeowner to:
- Replace all aged MCBs, RCCBs, and main switches.
- Use high-quality breakers with proper current ratings.
- Proceed with earthing system installation only after the DB upgrade.
- Conduct full testing after installation.
Once these steps are completed, his entire electrical system will not only be safer but also more reliable, especially during rainy weather when earthing and insulation performance are critical.
Safety Starts from the DB/ Fuse Box/ Kotak Agihan
Your distribution board (DB) is the heart of your home’s electrical system. It controls, distributes, and protects every circuit. But even the best wiring or new appliances mean little if your DB components are too old to protect them.
Installing an earthing system is a wise move, but it must be supported by functioning protection devices. Old MCBs, RCCBs and main switches cannot guarantee your family’s safety.
If your home still uses outdated MCB, RCD or Main Switch or if you’re unsure when your last DB upgrade was done, it’s time for a professional inspection.
Need Expert Electrical Help? Call a Trusted Wireman Near You
Power tripping or weak earthing can silently damage your home’s wiring and appliances. Let our wireman team handle it fast.
Call Alex (012-870 2699) for on-site DB inspection, RCCB & MCB replacement, and earthing installation anywhere in Ampang, Klang, Subang Jaya, Petaling Jaya, or Selangor.
Prevent electrical shocks and fire risks, act now to make your home safe again.
