What is a Type B RCD?
Type B RCDs must not be confused with Type B MCBs or RCBOs that show up in many web searches.
Type B RCDs are totally different, however, unfortunately the same letter has been used which can be misleading. There is the Type B that is the thermal characteristic in an MCB/RCBO and Type B defining the magnetic characteristics in an RCCB /RCD. This means that so you will find products such as RCBOs with two characteristics, namely the magnetic element of the RCBO and the thermal element (this could be a Type AC or A magnetic and a Type B or C thermal RCBO).  

Important to Note
A load requiring Type B protection with its own RCCB must not be down stream of a type AC/A/F RCD protected load as this section could stop the upstream RCD protecting the sub loads connected to it. If it needs an upstream RCD, that must also be Type B. This may need to be time delayed depending on the installation.
Load Interference
The correct selection of RCD /RCCB is extremely important because the load can cause interference that can block the wrong RCB/RCCD will be blocked and not respond within the safety requirements. Further, the installer needs to know the leakage current and may mean the end load being divided over several RCCB/RCDs.  Even computers have around 2mA leakage that means only 3 on a Type A RCD.

When 30mA Protection is Required
Where 30mA protection is required, it is often important that they double pole switch the circuit. Many RCBOs are only single pole which are totally unsuitable for outside loads such as ponds, garden lighting or spas /swimming pools.

Type B RCCB/RCDs are suitable for PV systems, DC motors with power source from AC supply inverter loads and car chargers.

RCCBs type B grant protection to persons and machineries in presence of DC current and high frequency AC fault current. Among the several types of RCBOs, type B provide the upmost level of protection.
Some applications’ examples are: protection of elevators, escalators, welding machines, electro-medicals’ instrumentation, ventilation systems, PV systems, EV vehicles charging stations.
For more information about technical characteristics, applications and Standard references concerning type B RCCBs, please click here:

Technical Information

RCCBs 4P type B are suitable to detect earth faults’ currents. In case the installations requires also protection from eventual overload and short-circuits, the RCCBs must be installed in series with MCBs or with fuses.
RCCBs’ mechanism is trip-free, that is the RCCBs can also trip when the lever is held in ON position.
All RCCBs are equipped with a green led signaling that the voltage is sufficient for product’s functioning as type B.
All products must be power supplied from the power side. Furthermore “cage” type terminals facilitate connection both through conductors (up to 35 mm² rigid and 25mm² flexible) and through busbars (both pin or fork types).