Guidance Note 3: Inspection & Testing (Electrical Regulations)

Product Information

BS 7671:2018 introduced requirements for additional protection for AC final circuits supplying luminaires within domestic (household) premises. If this is observed to be absent, BPG 4 recommends that a C3 classification code is attributed. The technical content of this section has been extensively revised and expanded. Requirements of this section now apply to:

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for their correct application. Many of the issues encountered when testing RCDs are down to user error as opposed to faulty RCDs. It may come as a surprise to some, but RCD testing should be carried out at the RCD with the outgoing wiring disconnected. However, this is not usually done. The usual live working procedures must be considered, and suitable precautions taken when carrying out work near live parts.On completion of the inspection and testing the inspector will provide an overall assessment of the installation in terms of its suitability for use, this will either be satisfactory or unsatisfactory depending on the classification codes which have been attributed to any observations recorded on the report.

The interval between each inspection and test will require an engineering judgment to be made based on the knowledge and experience of the inspector. The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 states that an electrical test is required for a rented property at a maximum interval of five years, but this could be reduced by the inspector, but this would need to be justified.

Cascaded RCDs for selectivity

I suggest you go and measure Zs on a real system with a real meter early in the morning, then go out for lunch and polish the meter probes and re-test with the same meter at the same point in the afternoon. The two readings will be both as valid, but are unlikely to be the same in all digits. As an aside what meters do you suggest with this accuracy (not precision) ? Note that two half lengths of meter lead is a good few milli-ohms on its own. I have used both Fluke and Meggar machines and neither is this good.

Since the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 came into force on 1 June 2020, the IET technical helpline has been inundated with calls related to the Electrical Installation Condition Report (EICR). This previous IET Wiring Matters article provides further information. In this article, we are going to answer some of the most common questions received and dispel some of the myths associated with the EICR. What is an EICR? Type AC RCDs are affected by residual DC components and can become desensitized or ‘blinded’ and may not operate within the required time or, in some instances, may not operate at all. Table 1 summarizes the various types of RCD referred in BS 7671:2018+A2:2022 and their resilience to DC components.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. In some cases, the inspector may not be able to reach a conclusion and further investigation will be required. In which case the observation will be attributed with F/I. The classification of further investigation should not be used to locate the problem, it should only be used where it is reasonably expected to reveal a dangerous or potentially dangerous situation. Whilst deficiencies observed on fire alarm and emergency lighting systems during the inspection may be worthy of a general note, a classification code should not be attributed. Summary The minimum IP rating for electrical equipment installed in zone 1 of a location containing a bath or shower is IPX4. A bathroom fan needs to be 12 V extra-low voltage