Guidance Note 3: Inspection & Testing (Electrical Regulations)

Product Information

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 following example is used to demonstrate how the differences in measurement between the cross-connection (usually at the origin of the circuit within the consumer unit or distribution board) and the mid-point in the ring occur. Example When writing responses to these challenging questions, make sure that both wording and explanations are clear and concise. In this context, it’s easy to drift into protracted answers, which go off on tangents and become too waffly. Examiners are simply trying to ascertain whether you’ve acquired the relevant knowledge. Therefore, keep answers extremely relevant and to the point. Besides, you only have 15 minutes to construct each response!

The IET Guidance Note 3: Inspection & Testing, 9 th Edition provides detailed yet simple-to-comprehend guidance on inspecting and testing electrical systems in accordance with IET’s updated 18 th Edition regulations and BS 7671:2018:2022 standards. V low voltage rated bathroom fans are permitted in zone 1 of the bathroom. All circuits must be RCD protected From Table 1, a 60 m 2.5/1.5 mm 2 ring final circuit only shows a change of one in the least significant digit in the reading as you move around the ring, but with the same ring final circuit wired in 4.0/1.5 mm 2, the change is five in the least significant digit on the instrument. This is a change of 25% of the lowest reading. The lowest reading deviates by 20% from the existing rule of thumb, and the highest reading is predicted by the rule of thumb. The longer the circuit, the more noticeable the difference in reading will be on a test instrument.It should be noted that those recommendations appearing in guidance taken from statutory instruments, British Standards or Codes of Practices could be subject to change as and when those documents are revised. It is the responsibility of the designer of the installation to be aware of, and to act on, the most up to date information and requirements at all times. The test is ‘open-book,’ which means candidates can bring supportive literature into the examination hall or ‘virtual’ environment. There are two pieces of key documentation that candidates should be in possession of whilst conducting their exam. These are Guidance Note 3: Inspection and Testing, 8th Edition, and the IET 18th edition wiring regulations guide (bs7671). Both of these items relate directly to the subject matter, and will be extremely useful throughout the multiple-choice assessment. They will also have been readily deployed during the initial course structure.

BS 7671:2018, Tables 41.2, 41.3, and 41.4 indicate the maximum earth fault loop impedance values, it’s important to note that these are the maximum values which should not be exceeded when the cable is at it’s assumed conductor operating temperature (70c).The EICR can be used to assist the duty holder in assessing the risk to determine the safety of the installation. The information in the report could be used to develop safety measures to mitigate the danger until remedial works can take place, such as isolation of an affected circuit. Is an EICR retrospective? It is clear to see from the definition that someone carrying out EICRs is required to have adequate education, training, and experience to do so. An inspection and testing qualification place is a good place to start, but it is also necessary that the inspector has the necessary experience. Common mistakes observed on EICRs Section D – Extent and limitations of inspection and testing Measurements on a ring final circuit wired with 2.5/1.5 mm 2 twin and earth cable shows very little change in instrument readings at each test point around the ring, even for the longest circuit lengths meeting voltage drop criteria. There is very little distinguishable change in the instrument reading during the test. As the difference in cross-sectional area between live conductors and cpc increases, the difference becomes more noticeable. With longer ring final circuits wired in 4.0/1.5 mm 2 twin and earth cable, the readings no longer appear approximately the same at each point on the ring, and differences in instrument readings become more noticeable. However, it is important to remember that Table 3.2 is titled ‘recommended initial frequencies of inspection of electrical installations.’ The first important word is ‘recommended’, it is exactly that, a recommendation and not a legal requirement. It is also important to note that this is for initial frequencies for new installations. It is worth noting that for domestic rented accommodation and houses in multiple occupation, the recommended maximum period between each inspection and test is five years or change of occupancy, which is often overlooked.

The written part of the assessment is particularly challenging due to the nature and construction of question sets. The themes and specific conditions captured in the first question of each, will correlate through to the second and third questions. This means that if the initial question is approached incorrectly, it could scupper responses for the remaining two. Therefore, although this is useful from a consistency perspective, it still presents delegates with a significant scoring risk. By ‘building’ question content up, examiners are looking to assess whether candidates have a firm grasp on sequencing and process flow. Candidate approach Rewireable or semi-enclosed fuses to BS 3036 as they are referred to in BS 7671:2018+A1:2020, are indeed still permitted providing the appropriate correction factor (0.725) is used when determining the size of the conductor. In fact, Table 533.1 identifies the sizes of tinned wire for use in semi-enclosed fuses. The days of selecting an RCD according to current rating and rated residual current alone are gone, now the designer must select the RCD according to the nature of the residual fault currents, including pulsed or steady-state DC components expected to be present.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. The inspector is also required to recommend a date for further inspection and testing to be carried out. These dates are often assumed or taken from Table 3.2 of IET Guidance Note 3 Inspection & Testing.