Power Electronics

The Benefits of MCB, RCCB, MCCB and ELCB Circuit Breakers

Circuit Breakers MCB, RCCB, MCCB, and ELCB Overview:

MCB MCCB RCCB ELCB- Due to the Advancement in Technology we are nowadays using a huge number of electrical appliances in our homes which have improved our lifestyle and have provided comfort and ease to our life but also has increased our life to many dangers as most of the appliances use electricity for their operation which indirectly exposed us to the hazards of electricity.

Suppose any device in our home gets faulty and current leaked through it wire to on its body so there will be no path for the current to bypass through which is the main reason for being electrocuted and this current will flow through our body causing serious injuries or eventually death. Here MCB, MCCB, ELCB, RCCB these apparatus come in handy by using these devices we can reduce the chances of being electrocuted which we will be discussing in this article so let’s start by knowing about the benefits of using them in a circuit and which one is best among all. Let us get to familiar with each of them individually.

All of the MCB, MCCB, RCCB, and ELCB are circuit breakers that are designed for serving a specific purpose.

Introduction to MCB

The MCB is abbreviated as Miniature Circuit Breaker which mechanically switches off the electrical circuits during any uneven condition in the electrical system such as overload and the short circuit conditions. Though fuse may sense these conditions but it has to be replaced, though MCB can be reset. The MCB is an electromechanical device which protects the electric wires and electrical load from overcurrent so as to ignore any kind of fire or the electrical hazards. By handling MCB is fairly safer and by it we can quickly restore the supply. Now when it comes to house applications MCB is the most favored choice for overload and short circuit protection. The MCB can be reset very fast and do not have any maintenance cost. The MCB works on bi metal respective principle which provides protection against overload current and solenoid short circuit current.


Introduction to MCCB

The MCCB is abbreviated as Molded Case Circuit Breaker which is an alternative type of electrical guard device which is used when loading current increases the range of a miniature circuit breaker. The MCCB delivers protection against overload short circuit faults and it is also used for switching the circuits which can be used for higher current rating and the fault level even in domestic applications. Here wide current ratings and high breaking capacity in MCCB find their use in industrial applications. The MCCB can be used for the protection of capacitor bank generator protection and the main electric feeder distribution. It provides adequate protection whenever an application needs discrimination adjustable overload setting or earth fault protection.


Introduction to RCCB

RCCB is abbreviated as Residual Current Circuit Breaker. The residual current device is fundamentally an electrical wiring device that disconnects the circuit whenever there is leakage of current flow through the Human body or current is not balanced b/w the phase conductor.  The safest device to detect and it trip against electrical leakage currents thus ensure protection against electric shock caused by direct contacts. The RCCB is commonly used in series with an MCB which guards them against over current and short circuit current. So both phase and neutral wires are connected through an RCCB device.  An extremely effective form of shock protection and widely used for protection from a leakage current of 30,100 and  300mA which is essential lifesaving equipment used to save the human body from shock and is compulsory in many areas for domestic installation.


Introduction to ELCB

The ELCB is abbreviated as Earth Leakage Circuit Breaker. It has the same role as RCCB but is voltage sensor device. Though this is old technology and is not in common use. The RCCB being a current sensitive device have a better advantage over ELCB.


Need of these Devices “Circuit Breakers”:-

As we know that electricity in our home has two wires one is a phase and the other is neutral. Suppose we have not used the above devices between these wires then in case of overload and short circuit we will end up destroying our valuable apparatus and our precious life.

How to reduce the chance of being electrocuted in our homes:-

MCB and RCCB/ECCB reduce the chances of being electrocuted by tripping when any fault like overload and short circuit happens and save the devices like generator and inverter or any other devices.

Condition 1:-

Suppose we have a pedestal fan in our home and it is connected to 220 v supply through the MCB (Miniature Circuit Breaker) and we have also provided the fan with the earth wire by taking a piece of wire connecting it to the body of the fan and the other end goes inside the ground; we do it to bypass the current in case of any fault like overload and short circuit in the fan which will leak the current to the body of the fan and the current from the body of the fan will go through the ground wire into the earth, which provides safe passage for the flow of the current. Now in case of such a fault, there are two possibilities the ground wire and phase wire will burn out making the circuit break. And the second possibility is that if the ground and phase wire are both of good quality then our MCB will get tripped automatically saving our valuable apparatus and life.

 Condition 2:-

We will assume the previous condition of ac fan connected to the 220 supply but in this case, it is connected through both MCB and RCCB now as the fan become faulty and the current leaks through it on to the body of the fan and as soon any person come in contact with the body of the fan by touching its body the current that has no path for flow has been provided with a path through the body of the person to the ground and the current will flow through the body of the person to the ground leading to severe injuries and if this flow continued for a larger time then it may cause the death of the person but in case of using this two device MCB and RCCB this flow will not possible for a long time in microseconds the RCCB will detect the problem that any fault like short circuit and overflow has occurred and will cut off the supply by tripping RCCB. The RCCB is connected between the apparatus and the MCB which make it able to have a record of the current flow through the circuit and as soon there is any fluctuation in the current flow through the body of the person or any other case it senses the problem and trips the supply in microseconds. It obeys the conservation of charge that the charge entering the circuit must be equal to the charge leaving the circuit.

Procedure for Practical Connection of RCCB and MCB:-

  • First of all, pass the phase and neutral wire through the input terminal of the MCB as mentioned on MCB.
  • Take the output of the MCB and supply it as the input of the RCCB.
  • Note done that MCCB has also listed symbols for input and output slots for both phase and ground wire.
  • Take the output of the RCCB and use it to power different apparatus or load of the home as per RCCB amps.

RCCB of rated 30amps is enough for a small load of the house. Whereas for industries and higher load higher-rated RCCB are also available in the market.

Installation circuit for RCCB and MCB


Tripping conditions for RCCB:-

We will be discussing ways to make an RCCB trip for checking purpose that how will RCCB behaves if we encounter such situations.


When the input phase and the output ground are shorted through a piece of wire the RCCB will trip.


When the output phase and the input ground are shorted through a piece of wire the RCCB will trip.


When the output phase and earth are shorted through a piece of wire the RCCB will trip.


For checking that the RCCB is operating correctly or not we can also trip the RCCB using the trip button available on the RCCB all we need to do is just turn the liver ON and press the trip button which will trip the supply and liver come back to OFF position,

This is a good practice to check for the RCCB tripping every month for safety that is the device working properly?.

The Condition in which RCCB doesn’t trip is when the output ground and the earth wire are shorted through a piece of wire the RCCB will not trip.


1 It is abbreviated as Miniature Circuit Breaker. It is abbreviated as Molded Case Circuit Breaker.
2 This is Rated current not more than 125 Ampere. This is Rated Current up to 1600A
3 The  interrupting current rating is under 10KA The  interrupting current ranges from around 10KA  85KA
4 The MCB is mainly used for low Breaking capacity requirement mainly domestic by Judging from their power capacities The MCCB is mainly used for both low and high Breaking capacity requirements mainly industrial.
5 The trip characteristics are normally not adjustable since they basically cater to low circuits. The trip current may be fixed as well as adjustable for overload and magnetic setting.


1. The RCCB refers to ear stands for Residual Current Circuit Breaker. The ELCB refers to Electric Leakage Circuit Breaker.
2. The new name and refers to current operated devices. The ELCB refers to a voltage-operated earth leakage device.
3 RCCB ensures 100% detection of leakage current and is available to sense the AC as well as DC leakage current. ELCB is not desirable as it can only detect current that flow back through the main earth wire.
4 The RCCB has no connection with the earth wire and that’s why it can trip when both currents phase and neutral are different and it withstands up to both the currents are same. The ELCB is working based on Earth leakage current. These devices measured the voltage on the earth conductor if this voltage was not zero this indicated a current leakage to earth.


We have concluded at the end that for a safe home and industry we should use these devices and proper earth connections and also have a check on these device for their working after a specific period of time as explained above.



Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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