Neither BS EN 61008-1 nor BS EN 61009-1 requires an indication of the operating characteristic to be displayed or visible when the device is installed. It may be necessary therefore to refer to manufacturer’s data to determine this information.

A fire or smoke detection system would fall into this definition. If this system is supplied from the electrical installation then an overvoltage could cause it to fail and, as such, requires protection. The simplest way to provide this protection may be to supply it at the distribution board or consumer unit. Table 1 summarizes the proposed changes to the Regulations specifying signs and notices in BS 7671.

What are the changes to the requirements for selection of RCD Types?

This essential update to the IET Wiring Regulations forms the national standard to which all new electrical installations and additions, and alterations to existing electrical installations in the UK are to comply. It is important tobecome familiar with the changes. Where an RCD is installed to provide additional protection, Regulation 643.8 requires that it should be:

This may make it necessary to refer to manufacturer’s data relating to the RCD under test and, in many cases may mean that the test instrument manufacturer may need to be consulted to determine how best to configure the instrument prior to testing. Some RCD test instruments however, have an adjustable residual operating current range allowing a value of 250 mA to be set, eliminating the above issue.The Wiring Regulations (BS 7671) regularly come under review to ensure all standards are compliant with today’s electrical needs. The verification of the effectiveness of the measures applied for additional protection is fulfilled by visual inspection and testing. Where RCDs are required for additional protection, the effectiveness of automatic disconnection of supply by RCD’s shall be verified using suitable test equipment according to BS EN 61557-6 (see Regulations 643.1) to confirm that the relevant requirements of Chapter 41 are met. Further information on RCD testing can be found in IET Guidance Note 3 Inspection and Testing and PD IEC TR 62350:2006 Guidance for the correct use of residual current-operated protective devices (RCDs) for household and similar use which states that ‘ The testing current should be applied between the upstream and downstream terminal of the RCD’, see Figure 4 extracted from IET Guidance Note 3 Inspection and Testing. This is where knowledge of relevant product standards is essential, it would be reasonable to expect a 40 ms maximum disconnection time for a test at five times I Δn as would be the case with an AC test. However, this is not the case as the product standard BS EN 61008 requires a half wave pulsating residual current of 0.35 A (350 mA), see Table 4 extracted from BS EN 61008-1:2012+A2:23-1:2012+A11:2015. Previously, effectiveness under 643.7 and 643.8 was verified where the RCD disconnects within 40ms when tested at a current equal to or higher than five times its rated residual operating current. This has now been aligned with 643.7 and 643.8 and the new regulations are as follows:

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.This time, Amendment 1 is withdrawn on 27th September 2022 to bring BS 7671 into line with other British Standards when they are reviewed. The requirements of Section 443 on protection against transient overvoltages has been completely rewritten with the risk assessment removed. There is no longer a requirement to perform a test using a test current equal to or higher than five times the rated residual current. What is an alternating current test?