What is the difference between an RCCB and an RCBO?
Understand the difference between an RCCB (earth leakage only) and an RCBO (combined MCB + RCD in a single unit) for electrical panel design.
What is the main difference between an RCCB and an RCBO? An RCCB (IEC 61008-1) detects earth leakage current only and must be paired in series with an MCB or fuse for overload and short-circuit protection. An RCBO (IEC 61009-1) combines residual current protection, thermal overload protection and magnetic short-circuit protection in a single device.
RCCB vs RCBO comparison table
| Criterion | Residual Current Circuit Breaker (RCCB) | RCBO (Combined MCB + RCD) |
|---|---|---|
| Standard | IEC/EN 61008-1 | IEC/EN 61009-1 |
| Earth Leakage Protection | Yes (10 mA, 30 mA, 300 mA) | Yes (30 mA, 300 mA) |
| Overload & Short-Circuit | No (requires separate MCB/fuse) | Yes (built-in B or C curve breaker) |
| Fault Selectivity | Trips the entire group of downstream circuits | Isolates only the faulty individual circuit |
| Category Link | Residual Current Relays | MCBs with Residual Current Protection |
Frequently asked questions
Does a 40 A RCCB trip on overload at 45 A?
No. The 40 A rating on an RCCB is its maximum continuous thermal current (In), not an overload trip threshold. Overload protection must be provided by an upstream or downstream circuit breaker.