Residual Current Circuit Breakers RCCB & RCBO | Schneider Acti9

An RCCB continuously monitors the current balance between the live and neutral conductors. Under normal conditions, every ampere leaving through the live wire returns through the neutral — the two values are equal. When a fault occurs — a person contacts a live part, cable insulation fails, or moisture compromises an appliance — some current finds an alternative path to earth, creating an imbalance. When this imbalance reaches the device's trip threshold (typically 30 mA), the RCCB disconnects the circuit in milliseconds, before a potentially lethal shock can develop.

Unlike a miniature circuit breaker (MCB), an RCCB does not respond to overload or short-circuit current — it must always be used in series with an MCB, or replaced by an RCBO which combines both functions.

RCCB vs RCBO — which to specify?

	RCCB	RCBO
Earth leakage protection	✓	✓
Overload protection	✗	✓
Short-circuit protection	✗	✓
Module width (typical)	2–4 modules	1–2 modules
Best for	Protecting groups of circuits	Per-circuit protection; space saving
Recommended	Extending existing installations	New build and refurbishment projects

RCCB and RCBO types — AC, A, B and selective

The type designation defines which categories of leakage current the device can detect:

Type AC — detects sinusoidal AC leakage only. Now obsolete; prohibited in new installations in most European countries
Type A — detects AC and pulsating DC leakage. The current standard for modern installations with inverter-driven appliances, heat pumps, washing machines and EV wallboxes on dedicated circuits
Type B — detects AC, pulsating DC and smooth DC leakage. Mandatory for EV charging stations, photovoltaic inverters, variable frequency drives and other power electronics that can produce smooth DC fault currents
Type S (selective) — incorporates a time delay to allow downstream devices to trip first; used in main distribution boards as part of a coordinated protection scheme

Sensitivity ratings and applications

Sensitivity	Primary function	Typical application
10 mA	Personal protection — high sensitivity	Medical locations, wet rooms, children's areas
30 mA	Personal protection — standard	Residential, offices, socket outlet circuits
100 mA	Fire prevention	Commercial lighting, fixed equipment
300 mA	Fire prevention — main distribution	Industrial distribution boards, main incomer protection

Schneider Electric Acti9 — available from stock

The Acti9 platform is Schneider Electric's modular protection range for residential, commercial and light industrial distribution boards. RCBOs combine the benefits of an MCB and an RCD in one compact device, saving installation time and space. The Acti9 iID (RCCB) and iDPN Vigi / iC60 Vigi (RCBO) families cover the full range of current ratings, sensitivity levels and types required for IEC 61008 and IEC 61009 compliant installations. Festo

Selection checklist

Before specifying, confirm:

Number of poles — 2P for single-phase, 4P for three-phase circuits
Rated current — 16, 25, 40 or 63 A (higher ratings available)
Sensitivity — 10, 30, 100 or 300 mA depending on protection function
Type — Type A for standard loads; Type B for EV chargers, PV inverters and VFDs
Device function — standalone RCCB (paired with existing MCB) or RCBO (combined in one module)
Selectivity — whether a time-delayed upstream device is required for coordination

Not sure which configuration to specify? Our engineers can assist with device selection, cross-referencing, and panel coordination for your project.

Typical applications

Residential and commercial distribution boards — socket outlet and lighting circuit protection
Industrial control panels — earth leakage protection for motor and process circuits
EV charging installations — Type B RCCB or RCBO as required by IEC 60364-7-722
Photovoltaic and solar installations — Type B protection for inverter output circuits
Outdoor and wet area installations — garages, garden supply points, construction sites
Main distribution boards — selective 100/300 mA upstream protection for coordinated tripping

What is the difference between an RCCB and an RCBO?

An RCCB provides earth leakage protection only — it will not trip on overload or short-circuit current and must be used in series with an MCB. An RCBO combines both functions in a single DIN rail module, providing per-circuit earth leakage, overload and short-circuit protection independently. RCBOs are the preferred choice for new installations where panel space and fault isolation per circuit are priorities.

Which type of RCCB or RCBO should I specify — Type A or Type B?

Type A is the current standard for most modern installations and handles AC and pulsating DC leakage from inverter-driven appliances, heat pumps and washing machines. Type B is required wherever smooth DC fault currents may occur — EV charging stations, photovoltaic inverters, variable frequency drives and three-phase rectifier equipment. Type AC is no longer recommended for new installations in most European markets.

Why specify 30 mA rather than 300 mA?

30 mA is the international standard for personal protection against electric shock — it is the maximum current that can be tolerated before serious physiological effects occur, and a compliant 30 mA device will disconnect within 300 ms at rated current. 300 mA devices are used for fire prevention at the main incomer level, where a lower sensitivity threshold would cause nuisance tripping from normal operational leakage across large installations.

Does an RCCB protect against short circuits?

No. An RCCB only measures the imbalance between live and neutral current — it does not respond to overload or short-circuit fault current. For complete protection, an RCCB must be used in combination with an MCB sized to the circuit, or the combination replaced by an RCBO which provides both functions in a single device.