Residual Current Circuit Breakers

Residual current circuit breakers are crucial safety devices designed for swift disconnection of electrical supply, preventing prolonged and potentially dangerous electric shocks. While they significantly reduce risk, it's important to note that brief initial shocks or simultaneous contact with both conductors can still pose hazards.

These solid, safe, and very widely used breakers automatically disconnect circuits upon detecting unbalanced currents between supply and return conductors. Any discrepancy in conductor currents indicates a leakage, signaling a potential shock hazard.

As a key component in automatic disconnection of supply (ADS) systems, RCDs eliminate reliance on human intervention. These devices typically operate within 25-40 milliseconds of detecting leakage currents exceeding 30mA, though this rapid response applies specifically to final circuits under 32 Amps.

How Does an RCBO Work?

An RCBO (residual current breaker with overcurrent protection) safeguards against two types of electrical faults. The first is residual current or earth leakage, which can occur due to wiring errors or accidental circuit breaks, such as cutting through a cable during DIY activities. Without prompt disconnection, such faults could lead to fatal electric shocks.

What are RCBOs?

The RCBO meaning extends beyond basic RCDs (residual current devices) or RCCBs (residual current circuit breakers). While RCDs and RCCBs provide rapid disconnection to prevent prolonged shocks, an RCBO breaker incorporates additional overcurrent protection.

RCBOs serve three primary functions: protection against earth fault currents, overload, and short circuit currents. For optimal safety and functionality, it's recommended to install an RCBO on each separate circuit, ensuring that a fault in one area doesn't compromise others. These devices disconnect circuits to protect both people and equipment when current imbalances occur, operating independently of other overcurrent protective devices within their rated short-circuit capacity.

When considering RCD vs RCBO, the key difference lies in the RCBO's additional overcurrent protection. This makes RCBOs particularly valuable in scenarios requiring comprehensive circuit protection.

The design and testing requirements for these widely used safety devices are meticulously outlined in the IEC/EN 61009 standards: "Residual current circuit-breakers with integral overload protection for household and similar uses (RCBO)."

In conclusion, RCBOs represent a critical advancement in electrical safety, combining the protective features of RCDs with overcurrent safeguards. Their widespread adoption in various settings underscores their reliability and effectiveness in preventing electrical accidents.

The second type of electrical fault is overcurrent, manifesting as either overload or short circuit. Overloading occurs when excessive electrical devices are connected, causing power transfer to exceed cable capacity. Short-circuiting, on the other hand, results from insufficient circuit resistance and high amperage multiplication, posing a greater risk than overloading.

The Lanx Type A Single pole RCBO, a solid, safe, and very widely used device, offers comprehensive protection. Its technical specifications include:

• Residual current characteristics: A
• Pole configuration: 1P+N
• Tripping curves: B, C
• Rated short-circuit breaking capacity: 6kA
• Rated current: 32A
• Rated voltage: 240V
• Rated frequency: 50Hz
• Rated residual operating current: 0.03A
• Tripping duration: instantaneous ≤ 0.1s
• Electro-mechanical endurance: 4000 cycles
• Screw diameter: M4
• Protection degree: IP20
• Fastening torque: 1.2N.m
• Mounting: On 35mm symmetrical DIN rail
• Terminal connection heights: H1= 19mm; H2= 22mm

This RCBO breaker exemplifies the integration of residual current and overcurrent protection in a single device