MCB is one of the genius inventions of mankind that is massively underappreciated. MCB is an abbreviation for Miniature Circuit Breaker, and this invention has been saving us thousands and lakhs of damage every day from short circuits and overloads electrical damage.

Normally when an MCB trips, we should be thankful that the MCB worked and it just saved us from fluctuations in electricity damaging our appliances connected throughout our house. But when the same MCB keeps on tripping multiple times a day, it becomes quite irritating. So today, we will be sharing important checks and ‘what to dos’ to help you correct the faulty MCB or replace it with a new one.

How Does an MCB (Miniature Circuit Breaker) Work?

MCB breaks the circuit whenever there is an overload or short circuit in Electricity. Thus, saving expensive appliances which would have otherwise got damaged.

The metallic plate inside the MCB overheats and expands whenever there is a current overload or short circuit. This metal expanding, in turn, releases a spring mechanism which turns it off breaking the connection and circuit.

Some MCB nowadays has an Electromagnetic mechanism, where a metal part inside turns into a magnet when a certain level of current flows through it. This in turn displaces the switch and turns it off breaking the circuit.

Reasons the MCB May be Faulty or Tripping Very Easily:

• Defective or Faulty MCB – If the MCB is tripping very frequently, then the most common reason could be a faulty part inside the MCB or the MCB as a whole. It could be recent damage or a defective MCB from the start and the solution would be to replace it with a new MCB.
  
  
• Overloaded Circuit –An overloaded circuit could be another reason why the MCB is tripping so frequently and causing inefficiency in the system. If this is the problem, then it’s best to call an electrician and get the circuit and electric connection checked and fixed.
  
  
• Faulty Appliance – A faulty appliance connected to the circuit could be another reason the MCB is tripping very frequently. In this case, MCB is working alright but we need to find the faulty appliance. Switch of all appliances and reset the MCB, then switch on one appliance at a time to see if the MCB is tripping. Voila! You have found your faulty appliance.
  
  
• Cheap or Low-Quality MCB – It’s been often seen that cheap and low-quality MCBs, from brands that use ineffective materials and metals inside the circuit breaker, are a major reason for MCBs working inefficiently and tripping very easily; or worse not tripping at all during a short circuit or current overload causing massive damages to appliances connected.
  
  
• Dust or Loose Connection – Sometimes when we purchase a new MCB; either the MCB Switch is dolly free or there is no electric continuation in the circuit breaker. The solution would be to bang the MCB on a flat surface with some pressure on each side 3-5 times, thus removing the dust and correcting the MCB.

Newly Purchased MCB Not Working?

f you have recently purchased the circuit breaker and after coming back home and installing it you realised that there is no electricity continuation in the MCB or that the MCB Switch has become loose and free often referred to as ‘Dolly Free’ then this advice is for you. If you haven’t recently purchased the MCB, then skip to the next section.

If you’re still reading then don’t worry, this is a common occurrence in new MCBs and the reason could be dust in between the metal connector inside the MCB, or some spring or clip is loose inside the miniature circuit breaker. The very simple home solution for this problem which solves almost 70-80% of new MCB issues is banging the MCB on a flat surface on each side 3-5 times.

Watch the video below for a brief explanation of the process

If the MCB is still not working, you can contact your seller for a return or exercise your warranty with the Brand Manufacturer depending on the time elapsed after purchasing the circuit breaker.

How to Check if the MCB is Faulty?

There are 2 ways to check whether the MCB is faulty or defective. The first is the process of elimination, and the second is to use a 230V multimeter voltage tester to check MCB faults.

First Way to Check for Faulty MCB – Process of Elimination

• Turn off all devices and appliances in the circuit and unplug all chargers and appliances. Reset or Switch MCB on.
• Now, switch on your devices and appliances one by one. The faulty appliance will trip the MCB.
• If none of the appliances tripped the MCB, then that means all appliances are fine and the fault maybe with the MCB or the wiring connection.
• Some MCBs give a burning smell or show discoloration to indicate damage.

Second Way to Check for Faulty MCB – Using a 230V Multimeter Voltage Tester

• Turn off and unplug all devices and attach the tester to the circuit.
• If the tester is showing at least 230V capacity, then the MCB is fine.
• If the multimeter is showing 0V, then the MCB is faulty.

These Miniature Circuit Breakers are a use-and-throw concept. It means that the faulty MCB cannot be repaired and you just have to buy a new one to replace it. We always recommend contacting a qualified electrician to replace your MCB or correct any wiring errors. Replacing the circuit breaker can cause further damage to your connection and appliance, not to mention the risk of
electrocution.

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The intensity of the excessive current determines the operation time of the MCBs, which are delay trip units. This means they are enabled if there is an appropriate overload to put the safe circuit in jeopardy.

An MCB is a magnetic switching system that can make, hold, and break the current under standard circuit situations while also breaking immediately under emergencies.

Why use an MCB?

MCBs are used to protect your domestic equipment and powerful industrial appliances from short circuits and excess current. A circuit breaker, unlike a fuse, can be reset to standard function after one use.

Working of MCB

There are two contacts, one of which is fixed and the other of which is mobile. A solenoid causes the movable contact to open when the flow reaches the predetermined limit, and the MCB cuts off, preventing the flow of current in the circuit. The MCB is manually switched on to resume the flow of current. This mechanism protects against faults caused by excessive current or overload.

Types of MCBs

Every MCB has a specific tripping curve, B, C, D, or even a very specialised curve that differs from MCB brand to brand. IEEE regulations create the B, C, and D curves.There are three types:

• Type B MCB

This form of MCB can trip at a rate of three to five times its current rating in an instance. These are usually used for resistive or small induction machines that have very low switching overloads.

• Type C MCB

This form of MCB can trip at a rate of five to ten times its current rating in an instance. These are typically used for high induction machines, such as small motors and fluorescent lamps, where shifting overvoltage is high. C-type MCBs are favoured in these situations because they can withstand the strongest short-circuit currents.

• Type D MCB

This MCB fires at a rate of ten to twenty-five times its maximum capacity in an instance. These are widely used for very high input voltage with a constant high input current. These are appropriate for a variety of industrial and commercial uses.

Advantages of MCBs over Fuse

• Identify the defective region of an electrical circuit quickly and easily.
• Resuming supply is easy.
• Improved user interface: A Knob.
• Electrically less dangerous.
• More current-sensitive than a fuse.
• Maintenance and repair costs are lower.

Disadvantages of MCBs

• The MCB is more costly than the fuse.
• The MCB distribution system is more expensive than a rewireable fuse panel.
• The possibility of overheating the circuit due to an individual who is not eligible to operate it has been eliminated.