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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? Regulation 411.3.3 has been redrafted and now has three indents. There is still an exception to omit RCD protection where, other than BA1, BA3 or children (BA2, BA3) and mobile equipment (not exceeding 32 A) for use outdoors, a suitably documented risk assessment determines that RCD protection is not necessary. The standard is maintained by the Joint IET/BSI Technical Committee JPEL/64, the UK National Committee for Wiring Regulations, and published jointly by the IET (formerly IEE) and BSI. Although the IET and BSI are non-governmental organisations and the Wiring Regulations are non-statutory, they are referenced in several UK statutory instruments, and in most cases, for practical purposes, have legal force as the appropriate method of electric wiring. [3]
If the Type A RCD setting is selected on the test instrument, the test current is increased by a factor of 1.4. Therefore, if the instrument is set to perform a test on a 30 mA RCD at five times I Δn, a test current of 210 mA (30 x 5 x 1.4 = 210 mA) would be produced which may not be sufficient to operate the RCD within the required time as the product standard requires a test current of 350 mA (0.35 A), as described previously. Additional requirements have been added for installations where the generating set or sets may operate in parallel with other sources including systems for the distribution of electricity to the public. Two new regulations have been introduced in this field, which correlate to earth electrodes. Chapter 55: Other Equipment The information covered in this section is general and related to fundamental principles you will need to adopt prior to beginning design work.The introduction of the 18th edition does not mean that work carried out aligned to previous wiring regulation versions are instantaneously obsolete. Therefore, no efforts need to be made to re-hash or undo any historical work conducted, unless this fails testing & inspection sequencing, poses a health and safety risk, or differs wildly from current regulations (although this should never be the case). The 18th Edition is the term commonly used in the industry when referring to the latest British Standards BS 7671:2018 Requirements for Electrical Installations, IET Wiring Regulations. In general, BS 7671 applies to circuits supplied at nominal voltages (U 0) up to and including 1000 volts AC or 1500 volts DC. The standard therefore covers the Extra Low Voltage (ELV) range (0-50V AC, 0-120V DC), and the Low Voltage (LV) range (50-1000V AC, 120-1500V DC). The frequencies covered for AC are 50Hz, used widely in the UK for the public supply to dwellings, offices, and commerce, along with 60Hz, and 400Hz found in certain commercial and industrial applications. It did not become a recognized British Standard until after the publication of the 16th edition in 1992. The standard takes account of the technical substance of agreements reached in CENELEC. [2]
A new Regulation 514.16.1 has been introduced requiring a label to indicate the presence of SPDs. However, there is an exception for domestic (household) premises or similar. Chapter 53 - Protection, isolation, switching, control and monitoring The last amendment to Chapter 41 is pertaining to a new regulation group (419). This relates to where an auto-disconnection is not feasible, such as on equipment with a limited short-circuit current. Please read and digest. Chapter 42: Protection against thermal effectsSection 411 contains a number of significant changes. Some of the main changes are mentioned below. In this example, appropriate protection against instances such as lightning strikes or switching must be delivered. A defence against transient over-voltages has to be provided in cases where the impact of not doing so (to quote directly from the 18th edition guide): Regardless of RCD type, e.g. AC, A, F or B, an alternating current test shall be used at the rated residual operating current (I Δn), with a maximum operating time not exceeding 300 ms for general non-delay type RCDs.
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