The requirements for testing RCDs have been simplified, a single test is all that is required to show compliance with the minimum requirement laid out in BS 7671:2018+A2:2022. Regardless of RCD type, the test is carried out using an alternating test current, applied at the RCD’s rated residual operating current I Δn, the maximum disconnection time is expected to be less than 300ms for a general non-delay type RCD. For S type time-delayed RCDs, the operating time should be 130 - 500 ms. Other kinds of RCD testing may be useful for fault finding purposes. This applies to the RCD test label, periodic test label, presence of SPD label (new requirement). The only exception is the warning notice of additional supplies which, if required, will still need to be present on the enclosure.

Further information on RCD operating and non-operating times can be found in the relevant product standards. Type A and Type AC RCCBs and RCBOs are manufactured to BS EN 61008 and BS EN 61009 respectively, whereas Type F and Type B RCCBs and RCBOs are manufactured to BS EN 62423. For all other cases, protection against transient overvoltages shall be provided, unless the owner of the installation declares it is not required due to any loss or damage being tolerable and they accept the risk of damage to equipment and any consequential loss. Probably the biggest change to be aware of in Amendment 2, is that the use of Arc Fault Detection Devices (AFDD) have changed from being recommended to a mandatory use in certain types of installations. Sub Committee A of JPEL/64 scrutinized the product standards for RCDs and noted the complexity of testing parameters, as well as the results permitted by the standards that could be used to prove the functionality of an RCD when bench tested in a laboratory. The type of test is selected on the instrument according to the RCD type. When the instrument setting selected is for an AC Type RCD, the test current applied is a 50 Hz alternating current. However, when the instrument setting selected is an A Type RCD, a pulsed direct current (DC) is superimposed on the 50 Hz AC waveform.

One solution could be to provide an overcurrent protective device within (or external to) the consumer unit, thus limiting the current through the assembly. The assembly will need to be certified by the manufacturer to the relevant part of the BS EN 61439 series and a declaration of conformity to this standard should be provided if requested. To simplify the specification of signs and notices in BS 7671, Regulation 514.9.2 is proposed. This proposed Regulation states:

It has been reported that contractors have experienced difficulties when testing 30 mA RCDs having a 0.25 A residual operating current characteristic. These difficulties seem to stem from the devices being tested at a current of 150 mA, rather than the necessary 250 mA (0.25 A), based on the assumption that using a test current of 5 I Δn will always be sufficient to cause the device to operate within the required time (0.04 s). This is not the case. Figure 2 Examples of the label required by proposed Regulation 514.13.1, when the label is not part of an earthing/bonding clamp to BS 951If you think you may have a faulty RCD, firstly ensure there are no factors within the installation that are influencing the results. Always carry out RCD testing in accordance with industry guidance and manufacturer’s instructions. This time, Amendment 1 is withdrawn on 27th September 2022 to bring BS 7671 into line with other British Standards when they are reviewed. A new Appendix 11 is included in the Draft for Public Comment, containing guidance on the requirements for labelling, aimed at those carrying out erection, initial verification and periodic verification. The Appendix advises on the minimum requirements for text and symbol size, summarized in Table 2 below. In addition, it advises the use of an easy-to-read sans serif font, giving examples of Arial, Calibri, Helvetica and Verdana. the use of Pink for the identification of a conductor whose sole purpose is a functional earth, along with the alphanumeric designation FE, was implemented by Corrigendum 2018, to align with the harmonized standard BS EN 60445:2017 Basic and safety principles for man-machine interface, marking and identification. Identification of equipment terminals, conductor terminations and conductors.