
A Residual Current Circuit Breaker (RCCB) is a safety device that is designed to automatically cut off the electrical supply in the event of an earth leakage, ensuring protection against electric shock and fire hazards caused by faulty wiring or electrical equipment. RCCBs detect the imbalance between the live (phase) and neutral conductors, which occurs when a fault happens, such as leakage current flowing through the body of a person. If the leakage exceeds a certain threshold, the RCCB trips, disconnecting the power supply.
How Does an RCCB Work?
RCCBs are equipped with a differential current transformer that continuously compares the current entering and leaving a circuit. Under normal circumstances, the current flowing into the live wire is exactly equal to the current flowing out through the neutral wire. However, in case of a leakage current — such as when someone touches a faulty appliance or if there is a short circuit to earth — the current will differ. In case an earth fault occurs, the current is able to find a way to the Earth via accidental means like touching a live wire. Due to this, the returning current via the neutral wire is reduced. The difference between the two currents is called Residual Current.
RCCB is outlined in such a manner that it ceaselessly senses and compares any contrasts (residual current value) in the current between the neutral and live wires. When the imbalance value of current crosses the set value (30mA or 100mA),the RCCB operates and isolates the circuit.
The RCCB detects this imbalance and automatically disconnects the circuit to prevent further damage or harm.
Here’s a simple breakdown of how an RCCB works:
- Normal Condition: The current flowing through the live and neutral wires is balanced, and the RCCB remains in the ‘on’ position.
- Fault Condition: When a leakage or imbalance occurs, for example, a person accidentally touches a live wire or an electrical fault causes current to leak to earth, the RCCB senses this imbalance and trips, cutting off the power.
- Restoration: The RCCB can be reset manually after the fault is corrected.
Function: The main function of an RCCB is to monitor the current flowing through the live and neutral conductors of an electrical circuit. It compares the currents, and if there is a difference (known as residual current or fault current), it quickly trips and disconnects the circuit, preventing the risk of electric shock.
Why is an RCCB Important?
- Protection from Electric Shock: The primary function of an RCCB is to protect humans from electric shocks. In case of a leakage or faulty wiring that leads to an exposed live current, the RCCB disconnects the power, potentially saving lives.
- Fire Prevention: Earth leakage currents can lead to overheating, which in turn can cause fires. RCCBs help in preventing such fires by detecting leakage currents early and disconnecting the faulty circuit.
- Equipment Protection: RCCBs also protect your electrical appliances and devices from potential damage due to leakage currents. By immediately cutting off the supply during a fault, the RCCB helps in preventing further deterioration of electrical systems.
- Compliance with Safety Standards: Many countries have made it mandatory to install RCCBs in residential, commercial, and industrial electrical installations to meet safety regulations and reduce the risk of electrical accidents.

Types of RCCBs
- AC RCCBs: These RCCBs are designed to protect against alternating currents (AC) only. They detect leakage currents in the AC circuit and disconnect the power in case of imbalance.
- A RCCBs: These RCCBs offer protection against both AC and pulsating DC leakage currents. They are particularly useful for systems that use electronic equipment, like computers or inverters, which might generate DC leakage currents.
- B RCCBs: These RCCBs offer protection against all types of leakage currents, including DC currents and high-frequency currents. They are used in specialized applications, such as electric vehicle charging stations and certain industrial setups.
RCCBs are available in two main types: 2-pole and 4-pole.
2 Pole RCCB
2-pole RCCBs are designed to protect single-phase circuits.
RCCB is utilized in a single-phase supply which contains a neutral wire and a live wire. The neutral wire and live wire are connected through input and output terminals. With the help of inbuilt switch, you can switch the RCCB on and off. It also has a test button that assists in periodically testing the functionality of the RCCB.
4 Pole RCCB
4 Pole RCCB is utilized in a 3-phase supply connection that includes a neutral wire and 3 phase wires. Again this has two ends where both the neutral wire and 3 phase wires are connected. The working principle is similar to 2 Pole RCCB
RCCBs play a vital role in electrical safety, particularly in preventing fatal electric shocks and minimizing the risk of electrical accidents. They are a crucial addition to electrical distribution systems, providing an extra layer of protection beyond circuit breakers and fuses.
Benefits of Using RCCBs
- Enhanced Safety: RCCBs provide peace of mind by protecting individuals from electric shock and reducing the risk of fire hazards.
- Preventive Measures: They are a proactive solution to detect faults before they escalate into serious issues like fires or injuries.
- Cost-Effective: RCCBs are relatively inexpensive devices that can save a significant amount in potential damage to electrical appliances, property, and even lives.
- Easy to Install and Reset: RCCBs are easy to install in most existing electrical circuits, and they can be reset once the fault is rectified.

Limitations of RCCBs
While RCCBs are highly effective in preventing electrical accidents, they do have certain limitations:
- Cannot Protect from Overload: RCCBs do not protect against overloads or short circuits, which can only be addressed by circuit breakers or fuses.
- Does Not Detect All Faults: RCCBs are designed to detect leakage currents, but they may not identify faults that don’t cause a significant imbalance between live and neutral wires.
Conclusion
The Residual Current Circuit Breaker (RCCB) is an essential safety device in modern electrical installations. It provides critical protection against electric shocks, electrical fires, and appliance damage caused by earth leakage currents. While RCCBs play a crucial role in safeguarding human life and property, they should be used in conjunction with other protective devices such as circuit breakers and fuses for comprehensive protection. Regular inspection and maintenance of RCCBs are vital to ensure their proper functioning and to enhance the safety of electrical installations in homes, offices, and industries.
By investing in RCCBs, you can significantly reduce the risks associated with electrical faults and create a safer living and working environment for everyone.
For the best quality RCCBs that will ensure the highest level of protection, you should opt for AXON ELECTRIC RCCB. AXON has been in this business for over 15 years now and has a number of customers all over who treats AXON as most trusted brand.