MCCB (Molded Case Circuit Breaker) and RCCB (Residual Current Circuit Breaker) are both types of circuit protection devices used in electrical systems, but they serve different purposes and provide different types of protection. Here are the main differences between MCCBs and RCCBs:

1. Function:

   • MCCB: A molded case circuit breaker is primarily designed to protect electrical circuits from overloads and short circuits. It trips and opens the circuit when the current exceeds a predetermined threshold, preventing damage to equipment and wiring.
   • RCCB: A residual current circuit breaker is designed to protect against electric shock caused by earth faults or leakage currents. It detects the imbalance between the live and neutral conductors and trips the circuit if the current flowing through the earth leakage exceeds a certain threshold.

2. Protection Type:

   • MCCB: Provides overcurrent protection against overloads and short circuits.
   • RCCB: Provides protection against residual currents, also known as earth leakage or ground fault currents.

3. Tripping Mechanism:

   • MCCB: Trips based on the magnitude of the current flowing through the protected circuit. It uses thermal and magnetic trip mechanisms to sense overloads and short circuits.
   • RCCB: Trips when it detects a residual current flowing to earth, indicating a fault. It uses a sensitive electromechanical or electronic trip mechanism to detect the imbalance.

4. Applications:

   • MCCB: Commonly used in distribution boards, switchgear, and power distribution systems to protect against overloads and short circuits.
   • RCCB: Commonly used in residential, commercial, and industrial installations to provide protection against electric shock and minimize the risk of injury or fire caused by earth faults.

5. Sensitivity:

   • MCCB: Generally less sensitive and may not detect small leakage currents.
   • RCCB: Designed to be highly sensitive and can detect even small leakage currents, typically in the range of milliamps.

In summary, while both MCCBs and RCCBs are important for circuit protection, they serve different functions and provide protection against different types of faults. MCCBs are primarily used to protect against overcurrents, while RCCBs are used to protect against residual currents and provide additional protection against electric shock. In many electrical installations, both MCCBs and RCCBs are used together to provide comprehensive protection against various types of electrical faults.