RCCB (RCD) Type B SK or B NK?
Type B RCCB Selection
If you are not familiar with the selection of different types of RCCBs, please click on the RCD selection button.
Type B SK or B NK characteristics are selected on the basis of the required RCD protection level and sensitivity (refer to BS 7671) and the leakage currents present in the installation at frequencies from 10 Hz < 150 kHz. Click on the document image to view.
Note: Before finalising the installation design and costings, verify that the equipment you intend to connect is actually compatible with your design proposals.
For example, many solar inverters and stand-alone VSDs / VVDs cannot be used with 30 mA RCDs.
Some inverters produce high frequency leakage currents > 300 mA i.e. they are not suitable for use in circuit designs based on BS7671 Regulation 422.3.9 (i), 532.2 … and special locations (Section 7) may specify restricted earth leakage currents e.g. 705.411.1