How to Check if MCB is Faulty?

To understand how to check if MCB is faulty, you must know what an MCB does. A miniature circuit breaker (MCB) is mainly designed to solve the two-current related problems. One is the overload current, and another is the short circuit. If an MCB is faulty, it needs a replacement. We replaced our MCB last year, and it was then my father explained to me how to know if an MCB is faulty. 

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How to Check MCB Fault?

• My father told me that if the MCB is tripping easily with even a simple load, it might be an indication that it has become faulty. 

• Sometimes, the switch breakers are overloaded, and this causes unusual and frequent tripping or heating of the MCB. I learnt that if the switch is not regulating the electric supply, there is a high chance of a short circuit. So, it is important to identify such overloading and act immediately. 

• Some faulty MCBs will produce a burning smell due to overheating. This was the case for us. We noticed our MCB was giving off a burning smell and then, my father found discolorations on the circuit breaker. This is another common sign of a damaged MCB. 

So, if you find any of the above signs or symptoms, act immediately and get your MCB replaced by a professional electrician. 

I can help you understand how to check MCB fault. The first thing you need to do is to perform a visual inspection for any damage or burn marks and use a multimeter to test for continuity when the MCB is in the "ON" position. There are other aspects that should be checked as well so let me highlight the prominent ones here.

How to Check if MCB is Faulty?

Here are some suggestions on how you can check if the MCB is faulty or not: 

• Visual Inspection: Check for visible damage or burn marks on the MCB.

• Reset the MCB: Turn the MCB to the "OFF" position and then back to the "ON" position.

• Test with a Multimeter: Use a multimeter to check continuity. If there's no continuity when the MCB is "ON," it may be faulty.

• Check Load: Disconnect all connected devices and check if the MCB resets properly. If it does, one of the devices may be faulty.

• Inspect Wiring: Look for loose connections, damaged insulation, or short circuits in the wiring.

• Overload and Short Circuit: Make sure no overload or short circuit condition is causing the MCB to trip.

These are faulty MCB symptoms you can detect yourself. However, if you fail to find the reason behind the MCB not working properly, hire a professional.

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Hi there,

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The miniature circuit breaker (MCB) is known as the modern version of the wire fuse. The MCB protects the devices from current overload or short circuits. But the MCB circuit breaks beyond a power level. Since MCB provides protection to devices from electrical damages therefore it is important to understand how to check if MCB is faulty. 

How to check MCB is working or not?

1. Switch off all the products and devices, and unplug your chargers and cables to reset the MCB.

2. Then turn on each device and if one appliance is causing the problem it will trip the circuit.

3. If this is the issue you will understand that your MCB is working fine.

4. If the devices are working properly then you may need to replace the MCB or the wiring.

5. You can also check a faulty MCB by checking discolouration. At times, it gives a burning smell to indicate the damage.

6. You can also use a 230 V voltage tester to check the MCB faults.

7. For this, you need to turn off the devices and attach the tester to the circuit.

8. If the voltage is at least 230V your MCB is working fine.

9. If the multimeter is 0V then your MCB is faulty.

I hope you understand how to check if MCB is faulty now.

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