Leakage Current Protection Device: RCD RCCB RCBO GFCI

RCCB

RCCB stands for Residual Current Circuit Breaker. RCCB is also known as RCB or RCD. RCD stands for Residual Current Device, while RCB stands for Residual Current Breaker. RCCB is an electrical wiring device that disconnects the circuit as soon as it detects a current leak to the earth wire. It also protects against electric electrocution or shock caused by direct contact.

RCBO and RCCBs, are residual current protection devices. This protection is achieved by monitoring the current flow in the line and neutral. In a healthy circuit, the current flow via the line equals the return flow in the neutral.

However, this return flow may not be equal to the line’s current flow in the event of any abnormalities. A residual current device will sense such a scenario and interrupt the circuit.

An RCD (residual current device) is a circuit breaker that monitors both phase and neutral currents and detects any imbalance between the two. It will trip when the imbalance exceeds a preset level (typically 30mA for touch protection, although higher levels are available). The RCD has a limited range of current ratings - typically 16A, 25A, 40A, 63A …. It does NOT have overload or short circuit protection and for full circuit protection, additional circuit breaker(s) will be required downstream of the RCD.

An RCBO (residual current breaker with overload protection) performs the same phase-neutral current imbalance detection function as an RCD but DOES have thermal and magnetic overload protection incorporated. The RCBO comes in the full range of current ratings associated with MCBs (miniature circuit breakers) - typically 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A …. with B or C tripping curves.

In a typical distribution board, where RCDs are used, 1 RCD is used upstream of 2 or more MCBs. So an earth leakage trip in one outlet could trip several outlet loops. In contrast, if RCBOs are used, an earth leakage trip will trip only the associated outlet loop. However the RCBO option is considerably more expensive.

What is the difference between RCD and GFCI?

They essentially are two names for the same device. In the UK and in Europe when English is used it is called an RCD (residual current device). In the US it is called a GFCI.

Now there are differences between US and Europe. In the US the triggering current is 5 mA. In Europe it is 30 mA. In the US they are electronic while in Europe they typically are electro-mechanical. In the US they often are in sockets while in, Europe they are more commonly in the panel.

IVY has launched several new RCDs, which differ from RCCBs on the market in the following points, IVY RCDs are sensors, not circuit breakers. Portable installation, small size and light weight. The occurrence of fault current will output an alarm signal instead of breaking the circuit. With Uart communication, the leakage current alarm value can be set.