This installation, or part of it, is protected by a device which automatically switches off the supply if a fault develops. Test six monthly by pressing the relevant test button(s) which should operate the device. Afterwards, manually switch on the device. If the device does not operate, or indicates a fault, seek expert advice. The person carrying out the testing must identify the operating characteristic of the RCD to determine whether the device should be tested at a current greater than or equal to either 5 Δn or 0.25 A as appropriate. BS EN IEC/IEEE 82079-1:2020 Preparation of information for use (instructions for use) of products. Principles and general requirements

For those that decide to continue to carry out all of the tests previously required, it is important to consider what the benefits really are and if the lifespan of the RCD be reduced, possibly to the point where it may not work when required. RCD testing issues The testing of RCDs has become more complex with the introduction of various different types of RCD. All RCDs, regardless of type, can detect and respond to an AC waveform. To simplify the testing procedure it is only now a requirement for verification purposes to carry out the AC test that is common to all types. So regardless of RCD type, the effectiveness is deemed to have been verified by testing the device using an AC waveform at a test current of 1 x IΔn. Where necessary, Regulations in BS 7671 specifying signs and notices have had their terminology modified to align with their classification as either warning notices or instruction notices. Whilst BS 7671:2018+A2:2022 doesn’t require other types of RCD testing, however additional tests are not precluded and may be useful for fault finding purposes, these tests could include: 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.

What are the different characteristics of the Type A setting on the test instrument?

RCD testers are designed and manufactured to BS EN 61557-6 Effectiveness of residual current devices (RCD) in TT, TN and IT systems for testing electrical installations. The standard requires that the instrument be able to verify correct disconnection of the supply in the event of a fault but it does not provide requirements for extensive product standard testing. Subsequently, not all instruments will be well suited to carrying out anything more than the most rudimentary of tests. What are the different characteristics of the Type A setting on the test instrument? Equipment with frequency controlled speed drives RCD can detect & respond as for Type A, PLUS high-frequency residual current

It is reasonable, therefore, to use a test current higher than the ‘trip rating’ of an RCD regardless of the application of the RCD.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. If 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.

BS EN 61009-1:2012+A13:2021 Residual current operated circuit-breakers with integral overcurrent protection for household and similar uses (RCBOs). General rules. Similarly, for instruments with a setting for Type B RCDs a multiplier of two times I Δn is applied as required by the product standard, BS EN 62423:2012 Type F and type B residual current operated circuit-breakers with and without integral overcurrent protection for household and similar uses. A house in multiple occupation is a property rented out by at least three people who are not from one “Household” but share facilities like a bathroom or kitchen. It was therefore agreed that the testing procedure could be greatly simplified and safety would remain unaffected since RCDs are, in any event, tested extensively by manufacturers prior to sale. What are the changes to the requirements for RCD testing?

BS EN 61008-1: 2012+A12: 2017. Residual current operated circuit-breakers without integral overcurrent protection for household and similar uses (RCCBs).

BS ISO 3864-1:2011 Graphical symbols. Safety colours and safety signs. Design principles for safety signs and safety markings When verifying whether an RCD can provide additional protection care must be taken to ensure that the device is tested at a test current appropriate to the operating characteristic to which the device was designed.

Cascaded RCDs for selectivity

Protection against transient over voltages shall be provided where the consequence caused by the over voltage could result in: 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 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. David Garrett, Product Management Manager at Deta, says “This is a reminder that the regulations affecting consumer units become mandatory on 28th September, and that all designers, developers and installers should be mindful that they need to be compliant from this date. Deta can assist in providing related information and product solutions to match your needs.”