What is an Earth Leakage Circuit Breaker (ELCB) & Its Working

Early earth leakage circuit breakers are voltage detecting devices, which are now switched by current sensing devices (RCD/RCCB). Generally, the current sensing devices termed RCCB, and voltage detecting devices named Earth Leakage Circuit Breaker (ELCB). Forty years ago, the first current ECLBs were introduced and about sixty years ago the first voltage ECLB was introduced. For several years, both the voltage and current operated ELCBs were both referred to as ELCBs due to their simple name to remember. But the applications of these two devices gave growth to the significant mix-up in the electrical industry. The manufacture of ECLB includes Fuji Electric, Major Tech, Siemens, ABB, Avera T&D, Telemecanique, Camsco, Crabtree, Orion Italia, Terasaki, MEM, and V guard.

What is an Earth Leakage Circuit Breaker (ELCB)?

An ECLB is one kind of safety device used for installing an electrical device with high earth impedance to avoid shock. These devices identify small stray voltages of the electrical device on the metal enclosures and intrude the circuit if a dangerous voltage is identified. The main purpose of the Earth leakage circuit breaker (ECLB) is to stop damage to humans & animals due to electric shock.

An ELCB is a specific type of latching relay that has a structure’s incoming mains power associated through its switching contacts so that the circuit breaker detaches the power in an unsafe condition. The ELCB notices fault currents of human or animal to the earth wire in the connection it guards. If ample voltage seems across the ELCB’s sense coil, it will turn off the power, and remain off until manually rearrange. A voltage sensing ELCB doesn’t detect fault currents from human or animal to the earth.

Earth Leakage Circuit Breaker (ELCB)
Earth Leakage Circuit Breaker

The ELCB notices fault currents of human or animal to the earth wire in the connection it guards. If ample voltage seems across the ELCB’s sense coil, it will turn off the power, and remain off until manually rearrange. A voltage sensing ELCB doesn’t detect fault currents from human or animal to the earth.

ELCB Function

The main function of an Earth-leakage circuit breaker or ELCB is to prevent shock while electrical installations through high Earth impedance because it is a safety device. This circuit breaker identifies tiny stray voltages on top of the electrical equipment with a metal enclosure & disrupts the circuit if a hazardous voltage is identified. The main purpose of ELCBs is to avoid harm to human beings as well as animals because of electric shock.

ELCB Operation

An electrical circuit breaker is a particular kind of latching relay and it has a mains supply of buildings that are connected throughout its switching contacts so that this circuit breaker will disconnect the power once earth leakage is identified. By using this, the fault current can be detected from life to the ground wire in the fitting it guards. If ample voltage comes out across the sense coil of the circuit breaker, then it will shut down the power & remain off until physically reset. An ELCB which is used for voltage-sensing does not detect fault currents.

How to Connect Earth Leakage Circuit Breaker

The earth circuit is adapted when an ELCB is used; the connection to the earth rod is accepted through the earth leakage circuit breaker by linking to its two earth terminals. One goes to the fitting earth circuit protective conductor (CPC), and the other to the earth rod or another kind of earth connection. Thus the earth circuit permits through the ELCB’s sense coil.

Types of Earth Leakage Circuit Breaker (ELCB)

There are two types of Earth Leakage Circuit Breaker (ELCB)

  • Voltage Operated ELCB
  • Current Operated ELCB

Voltage Operated ELCB

A voltage-operated ELCB device is used to detect a voltage to choose the Earth leakage. A single-phase voltage ELCB includes 6-terminals namely line in, line out, neutral in, neutral out, Earth, and fault. The metal body of the load is associated with the fault terminal of the Earth Leakage Circuit Breaker (ELCB) & the Earth terminal is associated with the ground. For usual working, the voltage across the trip coil is ‘0’, as the Load’s body is isolated from the supply line.

When an Earth fault happens on the load due to the interaction of line wire to the metal body, a current will run through the fault to the ground. The flow of current will set up a voltage across the trip coil, which is associated between E & F. The energized trip coil will tour the circuit to guard the load device & the user.

Voltage Operated ELCB
Voltage Operated ELCB

A voltage-operated ELCB detects a growth in potential between the threatened consistent metalwork and a distant isolated Earth reference electrode. They work as a sensed potential of around 50V to open the main breaker & separate the supply from the threatened premises.A voltage-operated ELCB includes a second terminal for linking to the remote reference Earth connection.

The Earth circuit is improved when an ELCB is utilized; the link to the Earth rod is delivered through the ELCB by linking to its two Earth terminals. One terminal energy to the installation Earth circuit protective conductor, aka Earth wire (CPC), and the other to the Earth rod or some type of earth connection.

Advantages of Voltage Operated ELCB

  • ELCBs are less sensitive to fault conditions and have few nuisance trips.
  • While current and voltage on the ground line generally fault current from a live wire, this is not continuously the case, therefore there are conditions in which an ELCB can annoyance trip.
  • When an installation of the electrical instrument has two contacts to earth, a near high current lightning attack will root a voltage gradient in the earth, offering the ELCB sense coil with sufficient voltage to source it to a trip.
  • If either of the soil wires becomes detached from the ELCB, it will no longer install will frequently no longer be correctly earthed.
  • These ELCBs are the necessity for a second connection and the opportunity that any extra connection to ground on the threatened system can inactivate the detector.

Disadvantages of Voltage Operated ELCB

  • They do not sense errors that don’t permit current through the CPC to the ground rod.
  • They do not permit only building system to be simply divided into many sections with independent error protection because earthing systems are typically used mutual earth, Rod.
  • They may be skipped by outside voltages from something associated with the earthing system like metal pipes, a TN-C-S or TN-S earth mutual neutral and earth.
  • As electrical leaky utilizations like washing machines, some water heaters and cookers might source the ELCB to trip.
  • ELCBs present an extra resistance & an extra point of failure in the earthing system.

Current Operated ELCB

RCCB is the generally used ELCB and it comprises of a three winding transformer, that has two primary windings and also one secondary winding. Neutral & line wires work as the two main windings. A wire-wound coil is the minor winding. The flow of current through the minor winding is “0” in the stable condition. In this condition, the flux owed to the current over the phase wire will be deactivated by the current through the neutral wire, meanwhile the current, that flows from the phase will be refunded to the neutral.

When an error occurs, a slight current will run into the ground also. This creates confusion between line and neutral current and that makes an unstable magnetic field. This encourages a current flow through the minor winding, which is associated with the sensing circuit. This will detect the outflow and direct the signal to the tripping system.

Current Operated ELCB
Current Operated ELCB

How to Check Earth Leakage Circuit Breaker

Earth leakage circuit breaker must be check once a year to whether that is working properly or not. Usually, the circuit breakers are in the ON position. Here we have listed the step by step process for how to test the earth leakage circuit breaker.

  • If the ELCBs are not working properly, then we should contact sales otherwise service engineers nearby us.
  • To deactivate the breaker, just push the operation switch, so that the power supply turns off.
  • Press the test button of the earth leakage circuit breaker by using a pointed object or a ballpoint pen.
  • Verify that the ELCB goes to the OFF position.
  • Revisit the ELB to the ON position.
  • Switch ON the main power.

Earth Leakage Circuit Breaker Vs MCB

The advanced version of Fuse is MCB and it is capable of disabling the circuit contact with supply once the current supply increases from the rated current of Molded Case Circuit Breaker. The operation of MCB is to break the contact to assist in securing the circuit from errors.

Similar to the Molded Case Circuit Breaker, the Earth Leakage Circuit Breaker also capable of disabling the circuit contacts through the mains supply. However different to the MCB, it doesn’t disable the circuit contacts within the case of an unexpected increase of current supply current. This type of circuit breaker is used to prevent the current supply when someone gets shocked because of the circuit operation.

The difference between ELCB and MCB is discussed below.



The short form of an Electric Leakage Circuit Breaker is ELCB.


The short form of MCB is Molded Case Circuit Breaker.
ELCB refers to voltage-operated earth leakage device.


MCB is an electromechanical device.

ELCB is an advanced one and it responds simply once the circuit leaks current toward earth.


MCB is a fundamental protection device used to restrict the current & fault within a circuit.
The earth leakage circuit breaker works on the principles of current balancing which means it computes the net of inward current as well as outgoing current.


According to the principle of the MCB which works on incoming current measurement for the circuit as well as its increase


ELCB is simply instant type simply because it must work instantly for any earth fault. MCB is a different type depending on the application as well as its characteristics
Therefore, with different reset of MCB, it’s optional to verify the circuit thoroughly before resetting ELCB. The trip ELCB specifies more alarming problem in the circuit as compared with the MCB
The rated current of ELCB ranges from 5 to 50A, at 240VAC The MCB rated current is not above 125 A.

Earth Leakage Circuit Breaker for Home

Earth leakage circuit breaker is used for homes for safe power supply. At present automation is used in independent houses, apartments & villas for controlling home appliances. But, the pressure on security is more because every year the death percentage is increasing in cities due to electrocution. To overcome this issue, installing an ELCB (Earth Leakage Circuit Breaker) is very important.

In Coimbatore, out of 4 Lakh residential houses, below 1 lakh homes have installed the ELCB, so generally, it is called a safety trip. The installation of this can be done in the vicinity of the main distribution board. Other states like Kerala & Karnataka have made it compulsory for their houses to include the safe trip. The cost of the safety trip is around 2k & it is a significant safety measure.

The residents can set up it even after building a house otherwise they can carry it to the new buildings if they live in rented houses. When industries set up the safety trip, commercial outlets & houses do not have it. The contractors of civil and electrical also use it while building a new house. At present, safety trips are using in buildings, industries, apartments, etc. One main condition to have the ELCB is correct wiring within the building.

Advantages of Earth Leakage Circuit Breaker

The advantages of ELCB include the following.

  • The ELCB is not a sensitive device to faults.
  • It is inexpensive as well as efficient.
  • It guards humans & animals against electrical shock.
  • In this procedure, once the installation of ELCB has two connections toward the ground, high current lightning which is nearby to the ground will strike to cause a voltage gradient within the soil, so the ELCB can sense the coil by sufficient voltage to cause it to safety trip.

Disadvantages of Earth Leakage Circuit Breaker

The disadvantages of ELCB include the following.

  • In certain situations, it fails to respond.
  • This circuit breaker requires a sound earth connection used for load protection.
  • Annoyance trips
  • The appliances like washing, machine, coolers & water heater may cause CKL to safety trip.
  • The external voltage may trip the circuit breaker from the connection of the earthing system like a metal pipe.
  • These circuit breakers do not notice an error that doesn’t supply current throughout CPC toward the earth rod.
  • They do not permit a particular building system to simply divide into several sections through independent error protection as the earthing system is linked toward the pipework.
  • Electrical circuit breakers introduce extra resistance & an extra point of failure into sufficient voltage to cause it to safety trip.
  • If the earth rod is connected near to another ground of a building, then a current with high earth leakage from other constructions can increase the potential of earth to cause a voltage disparity across the t earth to trip the ELCB once more.

Is Earth Leakage Dangerous?

The consequences of earth leakage current beyond 30mA can be caused to death. The sensitivity of 30mA can be necessary for safety within domestic applications wherever the person may approach in direct contact through the electric device in places like schools, labs, workshops, etc.

What Causes Leakage Current in a Circuit?

AC leakage current can be caused through a parallel blend of dc resistance & capacitance among an AC line which is known as voltage source & the conductive parts of the apparatus which are grounded. The leakage current can be caused through the DC resistance generally it is irrelevant as compared with the AC impedance of different parallel capacitances.

This current can stream from either AC or DC circuit within the apparatus to the earth & can be from the input or output. If the apparatus is not grounded properly, then the current supplies throughout other lanes like the human body.

Thus, this is all about an overview of Earth Leakage Circuit Breaker (ELCB), types of ELCB, and its working. We hope that you have got a better understanding of this concept. Furthermore, any doubts regarding this concept or to implement any electrical and electronic projects, please give your feedback by commenting in the comment section below. Here is a question for you, what is the function of ELCB?

Photo Credits:

  • Earth Leakage Circuit Breaker imimg
  • Current Operated ELCB wordpress

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