MCB and Main Switch Tripping at a PJ Home

Recently, I received a call from a homeowner in PJ who lives in a double-storey terrace house. The problem seemed small at first: the MCB at the top left corner of the DB box tripped. The customer tried to switch it back on, but the house still had no electricity. Even the main switch tripped, so they decided to call me for help. The customer said their whole family had to go through the night without electricity. The rooms were hot and stuffy, so they just wanted the problem fixed as soon as possible.

Many people, when faced with this kind of situation, they assume the MCB is faulty or that the electrician installed it wrongly. But in reality, there are many possible causes. An MCB is designed to cut off power automatically when there is an overload or short circuit, protecting your wiring and appliances. If both the MCB and the main switch keep tripping or if there is no power after switching them back on, it often means the wiring is overloaded, shorted or has loose connections.

First Inspection: Loose MCB and ELCB Wiring

When we arrived, the first thing we did was make sure all the main appliances were switched off to prevent shock during inspection. We opened the DB box and found that the tripped MCB had two wires sharing the same breaker. One wire was connected to the living room aircond, and the other was connected to the bathroom water heater. After checking closely, we discovered some wires were not tightened properly and showed slight wear. This kind of poor contact can cause unstable current, leading to tripping.

The ELCB and main switch connections were also not tight and felt loose. In a double-storey terrace, the wiring system is more complicated. On the ground floor, there are lights, sockets and a water pump. On the upper floor, there are air conditioners and water heaters. To find the real cause, every line has to be checked carefully, ensuring connections are secure and loads are properly balanced.

We also found that many circuits were looped. For example, two bedrooms shared the same lighting line and both the master and second bedroom air conditioners were looped together. This kind of wiring often causes tripping problems.

Since there was enough space in the DB box, we helped the customer by pulling out one of the wires and installing a dedicated MCB just for the water heater. This made the system safer and more reliable. we also suggested adding a dedicated RCCB (10mA) for all the water heaters. Because they’re installed in wet areas, if any leakage happens, the RCCB will trip instantly and protect lives.

Professional Troubleshooting Steps

As a professional electrician, my standard process is:

1. Switch off power – make sure the DB box and related circuits are not live.
2. Check wiring line by line – look for loose, damaged, or damp wires.
3. Check load distribution – ensure each MCB carries only a safe load.
4. Repair or replace MCB – change it immediately if faulty or poorly connected.
5. Test the circuits – switch the MCB back on and test each line step by step.

Why the Cheapest Electrician Can Cost You More

Here is the hard truth. Many customers choose the cheapest quotation thinking they are saving money, but in the long run it costs more. To cut corners, some electricians will:

• Use leftover old wires that heat up easily and are unsafe.
• Install low-quality switches, sockets, MCBs and RCCBs that fail quickly.
• Randomly loop live and neutral wires, so one problem affects many rooms.
• Loop multiple earth wires together, which can cause total failure of safety grounding.

At first, you may save a few hundred ringgit. But later, you will face repeated tripping, burnt sockets, damaged appliances or even fire and electrocution risks. The right approach is to use proper wiring, proper components, and separate each circuit clearly for safety.

So when choosing wireman, do not look only at the price. Safety and quality must always come first.

Electrical Issues? Call Alex for Short Circuit Repairs: 012-870 2699

This case shows clearly that saving a few hundred ringgit is not worth the risk. Wiring safety is very important. Even a small tripping problem may be a sign of wiring ageing, loose connections, or overload. If handled wrongly, it could lead to serious damage or danger.

In double-storey houses where the wiring runs are longer and the loads are heavier, regular DB box checks are even more important. You can do simple things like testing sockets and monitoring appliance loads, but for insulation resistance testing or wire tracing, always call a professional.

If your MCB or main switch trips, do not panic. Switch off power safely, check step by step, or simply call us. With professional troubleshooting, even a complex wiring system can be restored to safe and stable condition.

Need fast help? Call Alex at 012-870 2699 for troubleshooting and short circuit repairs.