In modern electrical systems, you will typically find MCCBs (or MCBs) for overcurrent protection and RCCBs (or RCBOs, which combine RCCB and MCB functionality in one unit) for earth leakage/shock protection. The old voltage-operated ELCBs are rarely, if ever, installed in new constructions today.
| MCCB (Molded Case Circuit Breaker) | RCCB (Residual Current Circuit Breaker / RCD) | ELCB (Earth Leakage Circuit Breaker – Voltage-operated) RCCB (Residual Current） | |
| Primary Protection | Overload and Short Circuit | Earth Leakage (via current imbalance between live/neutral) | Earth Leakage (via voltage on earth wire) |
| Human Safety | Indirect (by protecting circuits from damage that could lead to hazards) | Direct and highly effective against electric shock | Yes (but limited and older technology) |
| Operating Principle | Thermal (overload) and Magnetic (short circuit) | Compares current in live and neutral wires; trips on imbalance. | Detects voltage difference between protected metalwork and external earth rod. |
| Earth Connection Needed? | No (for its own operation, but circuit needs grounding) | No (monitors current differential within the circuit itself) | Yes (requires a specific connection to a dedicated earth electrode) |
| Current Rating | High (typically 100A to 3200A) | Medium (typically 10A to 125A), sensitive to small leakage currents (10-300mA) | Varies, but less common in new installations |
| Adjustability | Often adjustable trip settings | Fixed sensitivity (e.g., 10mA, 30mA, 100mA, 300mA) | Generally not adjustable |
| Modern Usage | Widely used in industrial/commercial applications | Widely used and often mandatory for shock protection in homes and commercial areas | Largely obsolete, replaced by RCCBs |
| Combined With | Often used as main breaker; may be combined with RCD/RCBO modules. | Always used with MCBs/MCCBs for complete protection (RCBO combines both). | Would have been used with MCBs/fuses for overcurrent protection. |
