Working Principle Of Earth Leakage Circuit Breaker(ELCB) And Its Advantage and Disadvantages

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 as RCCB and voltage detecting devices named as 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 its 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 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 .

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.

Earth Leakage Circuit Breaker
Earth Leakage Circuit Breaker

Types of Earth Leakage Circuit Breaker (ELCB)

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

  • Voltage Operated ELCB
  • Current Operated ELCB
Types of Earth Leakage Circuit Breaker
Types of Earth Leakage Circuit Breaker

Voltage Operated ELCB

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) & 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 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 become 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 an 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 as metal pipes, a TN-C-S or a 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 a confuse 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 signal to tripping system.

Current Operated ELCB
Current Operated ELCB

Thus, this is all about 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?

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  1. Thanks for your response and looking toward for more information in future.lasisi ,an electrical technicians

  2. Sir,
    Thank u for the above article. We are using RCCB in 24V circuit. If we press the test button, RCCB is not tripping. What might be the reason. It’s a 230V, 300mA RCCB. And RCCB require in a 24V circuit?
    Pls provide the details.
    Thank u.


    Hello Sir,
    i am a Safety officer working at SAGO Industry in Saudi Arabia
    its very ,amazing Advantaged theory

  4. I would like to understand working principle of ELCBs ,RCCBs and RCDs and its application whether its is changing as per product.I would like understand its circuit diagram ,block diagram specification standards i.e.IEC/ASTM/IS or other safety related specifications in IEEE.

    1. Tarun Agarwal says:

      Hi PRAVIN

      I sincerely appreciate your kind response regarding my article

      For more details please mail us on

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