Earth Leakage Protection
⚡ Earth Leakage Protection
Earth leakage protection disconnects power immediately when current leaks from a live conductor to earth, preventing electric shock and electrical fires caused by insulation failure or faulty equipment.
🟦 What Earth Leakage Is
- Leakage current flows outside the intended L → load → N path
- Caused by damaged insulation, faulty equipment, metal enclosures, or human contact
- Even 30–50 mA can be fatal — far below MCB trip levels
🟧 How Earth Leakage Protection Works
- Compares live vs neutral current
- Under normal conditions, currents are equal
- If an imbalance (residual current) is detected → device trips within milliseconds
🟨 Main Types of Earth Leakage Devices
- RCCB/RCD — detects leakage only; no overload/short‑circuit protection
- RCBO — RCD + MCB combined (leakage + overload + short‑circuit)
- ELCB — older voltage‑operated type; largely obsolete
🟩 Why MCB Alone Is Not Enough
- MCB detects overcurrent, not leakage
- A person may draw 30–50 mA — lethal but too low to trip an MCB
- Only an earth leakage device will disconnect the circuit
🟫 Typical Leakage Ratings
- 10 mA — special sensitive applications
- 30 mA — personal protection (homes)
- 100 mA — equipment/fire protection
- 300 mA — industrial fire protection
🟧 Singapore Context
- RCCB/ELCB mandatory in homes
- Missing a device can lead to fines up to SGD 5,000
- Located at the DB, with a TEST button for monthly checks
⭐ One‑line summary
Earth leakage protection detects residual current and trips instantly to prevent shock and fire — something an MCB alone cannot do.
