About Type B RCDs

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.

Residual and current leakage components with reference to Type B RCDs and RCCBOs

Notes relating to table:

(1) Type B RCCBs detect residual currents and trip if the smooth DC current exceeds the trip threshold. NOTE: Type A, AKV and F will function safely with smooth DC residual currents present up to the levels indicated but they do not detect smooth DC. Therefore, they must not be installed upstream of Type B RCCBs.

(2) Type EV RCCBs trip if the smooth DC current > 6mA. ie: They must only be used for protecting a single EVCP.

Type B RCD Features

Each unit will be supplied with a test certificate using a Megger MFT1721 Type B RCD Tester.

These Type B RCD units should only be selected and installed by a qualified professional.

Three module Single Phase units will be available later in 2019, call us on 01243 842888 for information.

Single phase and 3 phase Type B RCDs are all in four module enclosures and, with low volume sales and a very small price difference, at present we are only stocking 3 phase and neutral units.



* 63A
* 4 Pole (3 phase and neutral, can be used for single phase)
* 30mA  
* 4 module 35mm din rail mounting

Trade Price:  £164.00 + VAT  including UK three working day delivery.
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Single phase and 3 phase Type B RCD

Electair exports ltd
5 arun business park, bognor regis, west sussex, po22 9sx
TEL: +44 (0)1243 842888

Company No. 01970455 - VAT No. 543 8115 51

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