Understanding Working Principles And Functions Of RCCB

RCCB stands for Residual Circuit Current Breaker while RCD means Residual-Current Device. RCCB is an electrical wiring gadget whose job is to delink the circuit when it identifies current leaks to the earth wire. The device also protects against electrocution or electric shocks due to direct contact.

RCCB’s Functions

RCCB has an attached mechanical switch with residual tripping capability. As stated above, this device will break the circuit when it detects an earth fault or current leaking to the earth. In this way, it protects human life.  On its own, an RCCB can manage a residual current or fault of 1kA if it is an earth fault.

As per wiring rules, other devices can be made to operate along with RCCBs to offer protection. This can assist in enhancing the RCCB’s short circuit rating. For instance, an RCCB with a 1kA rating would be able to function at a fault level greater than 1kA.

A fault means an unusual electric current. For example, a short circuit occurs due to a fault where the current exceeds the typical load. It can also be termed residual current.

What is RCBO (Residual Circuit Current Breaker with Overload protection)?

RCBO IS an RCCB that has a built-in MCB or Miniature Circuit Breaker. It safeguards against short circuit currents, overloads, and earth fault, and thus protects lives similar to an RCD.

What is ELCB (Earth Leakage Circuit Breaker)?

ELCB is a voltage sensor that has a similar function to an RCCB. It is ideal for high current loads and three-phase circuits. The tripping delay and residual current level can be adjusted, permitting selectivity among various circuit breakers. However, ELCB is a relatively old gadget, and RCCB offers more benefits.

RCCB’s Working Principle

In an ideal circuit, the current that moves through the circuit through the live wire is the same as the returning current through the neutral wire.

But when an earth fault occurs, current accidentally moves to the earth wire, for example, accidental contact with the open wire. RCCBs reduce the current coming back through the neutral wire. The current difference between the neutral and live wire is termed residual current. An RCCB is built to detect the residual current continuously. Therefore, if the residual current does not exceed the limit, the RCCB will delink the circuit.

RCCB Pole Types

  • 2 Pole RCCB – Utilized in a one-phase supply connection that only has a neutral and live wire.
  • 4 Pole RCCB – Utilized in a three-phase supply connection. It also serves as an additional connection for the supply’s neutral
  • 3 Pole RCCB – Comparable to a 4 Pole RCCB but only has three wires of a three-phase solution.

RCCB Ratings

  • Residual Current Sensitivity – 1000mA, 500mA, 300mA, 100mA, 30mA, 10mA
  • Different Residual Current Sensitivity Tripping level has s a purpose
  • The ideal tripping level for full shock protection is 30mA like the Schneider Acti9 RCCB
  • If you are unable to utilize a 30mA gadget, you can use one with a 100mA tripping level, which can still give some shock protection ability
  • A 300mA device should not be utilized for shock protection; it is ideal for equipment and fire protection

RCCB Limitations

  • Does not provide protection from live-neutral shocks
  • Nuisance tripping: Unexpected electrical load changes can lead to a small current flow to earth; RCCBs may simply disconnect as they are sensitive and function swiftly
  • Built to operate only on normal supply standard waveform
  • RCCB does not protect against current overloads, which mean live-neutral faults; RCCBs will not trip and could suffer damage 


Companies like Schneider offer a range of quality RCCBs at an affordable price. You can thus get protection from electrical mishaps at a relatively low cost. Now that you know about the working principles and functions of RCCBs, it is recommended that you get advice from licensed professionals on suitable electrical systems, including RCCBs for your business.

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