RCCBs

An RCCB, or residual-current circuit breaker, is an earth-leakage protection device used by electrical contractors, panel builders, and facility engineers to protect personnel and equipment against electric shock and the risk of electrical fires in residential, commercial, and industrial installations.

RS NZ stocks RCCBs in 1-, 2-, 3-, and 4-pole configurations, across a range of current ratings and trip sensitivities, with DIN rail mounting for direct integration into distribution boards. The range includes devices from ABB, Schneider Electric, and Siemens, covering both standard and Type A devices for modern electronic loads.

How an RCCB Works

An RCCB continuously monitors the current flowing in the live and neutral conductors of a circuit. Under normal operation, these values must be equal: all current entering via the live wire returns via the neutral.

If a fault develops, whether from a person contacting a live conductor, insulation failure, or an equipment fault, some current leaks to earth rather than returning via neutral. This imbalance, the residual current, is detected by an internal toroidal transformer.

When the residual current exceeds the rated trip threshold, typically 30 mA for personal protection, the RCCB trips and disconnects the circuit within milliseconds. It is important to note that RCCBs protect against earth leakage only and provide no protection against overcurrent or short circuits.

RCCB vs RCBO - What's the Difference?

RCCBs and Residual Current Circuit Breakers with Overcurrent Protection (RCBOs) are both types of Residual Current Devices (RCDs), but they serve different roles in a circuit.

RCCB

An RCCB detects and disconnects only in the event of earth leakage. It monitors the imbalance between live and neutral currents and trips when residual current exceeds its rated sensitivity. It provides no protection against overcurrent or short circuits, and must therefore be used alongside a miniature circuit breaker (MCB) in the same circuit to provide complete protection against all fault types.

RCBO

An RCBO combines earth-leakage protection with overcurrent and short-circuit protection in a single device. It serves as both an RCCB and an MCB, making it more compact and simpler to wire for individual circuit protection, particularly on commercial distribution boards where panel space is limited.

Types of RCCBs

RCCBs and RCDs are usually mounted on DIN rail and are available across three key classification axes:

By Number of Poles

Two-pole RCCBs protect single-phase circuits with live and neutral conductors. Four-pole RCCBs are used for three-phase installations with neutral, disconnecting all live conductors simultaneously on a fault. Three-pole devices are used in three-phase circuits without a neutral.

By Trip Sensitivity (Sensitivity Class)

A 30 mA trip sensitivity is the standard for personal shock protection in residential and commercial circuits. Sensitivities of 100 mA to 300 mA are used for equipment and fire protection upstream, where nuisance tripping at 30 mA would be impractical.

By Waveform Type

Type AC devices respond to sinusoidal alternating residual currents only. Type A devices detect both AC and pulsating DC residual currents, making them suited to circuits supplying modern electronic equipment, LED drivers, and appliances with switched-mode power supplies. Type A is the recommended standard for most current residential and commercial installations.

Features and Benefits of RCCBs

RCCBs offer a range of safety and operational benefits, helping protect people, equipment, and electrical installations from the risks associated with earth leakage faults.

• Fast Disconnection: RCCBs compliant with IEC 61008 trip within 40 ms at five times the rated sensitivity, well within the physiological threshold for electric shock, minimising the risk of injury to personnel.
• DIN Rail Mounting: Most RCCBs are designed for DIN rail mounting, allowing straightforward integration into distribution boards and consumer units.
• Wide Current Rating Range: Our range covers common ratings including 16 A, 25 A, 40 A, 63 A, 80 A, and 100 A, supporting circuit sizing across residential, commercial, and industrial applications.
• Type A Devices Available: Type A RCCBs detect both sinusoidal AC and pulsating DC residual currents, providing appropriate protection for circuits supplying variable speed drives, EV chargers, solar inverters, and equipment with switched-mode power supplies.
• IEC 61008 Compliance: Various devices from leading brands meet the IEC 61008 standard, helping ensure consistent performance and safety for residual current protection in electrical installations.
• Leading Brand Reliability: ABB, Schneider Electric, and Siemens are globally recognised for consistent product quality and long service life in demanding electrical installation environments.

Choosing the Right RCCB

Selecting the correct RCCB requires matching the device to the circuit type, load current, protection level, and installation environment:

• Number of Poles: Use a 2-pole RCCB for single-phase circuits with live and neutral conductors. Use a 4-pole device for three-phase installations with a neutral, where all live conductors must be disconnected simultaneously during a fault.
• Current Rating: Select a rating that matches or exceeds the maximum load current of the protected circuit.
• Trip Sensitivity: Specify 30 mA for circuits where personal shock protection is the primary requirement, as required by AS/NZS 3000:2018 for socket outlet circuits, lighting circuits in domestic installations, and all circuits in wet areas. Sensitivities of 100 mA to 300 mA are appropriate for upstream equipment and fire protection applications.
• Type AC vs Type A: Specify Type A for circuits supplying variable speed drives, EV chargers, solar inverters, LED drivers, or any load with switched-mode power supplies that generate pulsating DC residual currents. Type AC devices are not capable of detecting these fault signatures.
• RCCB vs RCBO: If the circuit does not already have dedicated overcurrent protection from a separate MCB, consider an RCBO instead, as an RCCB alone will not protect against overload or short circuit faults.

Applications of RCCBs

RCCBs are installed across a broad range of electrical environments common to RS NZ buyers:

• Residential Consumer Units: Protecting bathroom, swimming pools, and outdoor circuits where 30 mA RCD protection is mandatory under AS/NZS 3000:2018. A single RCCB upstream of a bank of MCBs provides cost-effective earth leakage protection for multiple circuits simultaneously.
• Commercial Buildings: Providing earth leakage protection for lighting and general power circuits in offices, retail, and hospitality environments, where separation of earth fault protection from overcurrent protection simplifies distribution board design.
• Industrial Distribution Boards: Used as upstream earth leakage protection for equipment circuits, particularly where a single RCCB covers a group of MCB-protected outgoing circuits in switchgear panels and motor control centres.
• Construction Sites: Temporary supply installations require earth-leakage protection for portable tools and temporary distribution boards, where personnel are frequently in contact with equipment under exposed or wet conditions.
• Swimming Pools and Wet Areas: AS/NZS 3000:2018 Section 6 mandates RCD protection for all circuits in areas at increased risk of electric shock, including swimming pools, spas, bathrooms, and saunas, thereby making RCCBs a compliance requirement in these environments.

RCCBs work alongside MCBs, RCBOs, and surge protection devices, available from RS NZ, to provide comprehensive circuit protection in compliant electrical installations.

Buy RCCBs Online from RS NZ

Looking for a trusted supplier and distributor of RCCBs and residual current devices? RS NZ offers devices from ABB, Schneider Electric, and Siemens across 2- and 4-pole configurations, multiple current ratings, and Type AC and Type A sensitivity classes. Browse the full range online, filter by specification, and order with confidence for delivery across the country.

Ordering and Delivery Information for NZ

To order an RCCB from RS NZ, place an order online on our website or call us directly. Once your order has been placed, you will receive an order confirmation and can track its progress through dispatch updates.

Delivery options are available to suit different purchasing requirements, with lead times varying depending on product availability and stock location. For complete delivery details, visit our delivery page.