Guidance Note 3: Inspection & Testing (Electrical Regulations)

Product Information

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. To demonstrate competence, inspectors will need to have a high level of experience and knowledge of the type of installation to be inspected. They will also further demonstrate that they have undergone training and education in inspection and testing with evidence of qualification(s) from a recognised examining body.

A good simulation of our example with similar values, but giving readings in kΩ instead of Ω, can be made using six 47 Ω and six 120 Ω resistors to represent the line and cpc conductors of the ring final circuit respectively. As shown in Figure 9, these can be connected as a cross-connected r 1 and r 2 as in Step 3 of the ring final circuit continuity test. An EICR is a factual report on the condition of an electrical installation and suitability for continued use.They are different terms, but they all mean the same thing, the person carrying out the inspection and testing is required to have the correct qualifications, experience and knowledge. The requirements for RCD testing in BS 7671:2018+A2:2022 are given in the notes to Regulation 643.7.1 for fault protection and Regulation 643.8 for additional protection. A note in each section states the requirements and the key points are highlighted below. 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: When the Type A setting is selected on the instrument, a half wave pulsating residual test current superimposed on a smooth direct current of 6 mA is produced, which effectively applies a 1.4 multiplier to the rated residual current (I Δn). For example, if the 30 mA setting is selected, the RCD will be subjected to a test current of 42 mA (30 x 1.4 = 42 mA).

We often get enquiries advising that an EICR has been carried out and the customer has been advised that their installation needs to comply with the latest edition of BS 7671, which is not the case. Regulation 514.12 (Notices: periodic inspection and testing) now contains an exception for domestic (household) premises in certain situations.Predicted measured resistance = r y//r g = 0.6511×0.3515 ÷ (0.6511+0.3515) = 0.2283 Ω Results and conclusion 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

Changes include the addition of new regulations (relocated from Chapter 53) covering the impact and the installation of heating cables. Chapter 82 - Prosumer’s low-voltage electrical installations Minor changes have been made to the model forms and guidance for recipients. These include the addition of fields Predicted measured resistance = r y//r g = 0.5762×0.4264 ÷ (0.5762+0.4264) = 0.2451 Ω Step 3, resistance at Test Point 6 Table 51 has been modified slightly to take into account changes of colour identification for DC and abbreviations have been added. Regulation 422.2 now introduces separate requirements for escape routes and a new concept of 'protected escape routes'. Reference to conditions BD2, BD3 and BD4 has been deleted. Chapter 44 - Protection against voltage disturbances and electromagnetic disturbances

RCD testing issues

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 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 A typical spec is more like this maker's data for the LTW 425 - and that is a dedicated loop tester, not a compromised design to make a multi function tester all fit in one box, they tend to be worse.

There is an extra level of qualification and competence achieved, beyond the standard four-year vocational route commonly followed by qualified inspectors and testers. Regulation 544.1.1 concerning main protective bonding conductors has also been revised. Chapter 55 - Other equipment 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. And now the part of the resistance of the street main, and the real external voltage, will depend on other user's loads, and may change without warning if the DNO needs to change a transformer or make a repair to cables in the street. If a consumer unit is made from combustible material (e.g. plastic), BPG 4 recommends that the presence of a plastic consumer unit is worthy of a note, but does NOT warrant a classification code. If the consumer unit is located under a wooden staircase or within a sole route of escape from the premises, a C3 classification code is recommended.A person carrying out an EICR is required to be competent. The term skilled person (electrically) is used in BS 7671:2018+A1:2020, defined as below: or predicted reading by existing “rule of thumb” = (r 1+r 2)÷4 = 0.25 Ω Step 3 of the ring final circuit test Some ‘fuse boxes’ may contain an asbestos pad which effectively served as a flash guard. In the event that a fuse wire needs to be replaced, it is likely to release asbestos fibres, which would not be considered acceptable. For information on replacing an asbestos-containing fuse box, see HSE a33 datasheet. IET Wiring Matters article asbestos guidance for electricians provides general information on asbestos likely to be encountered by electricians. Regulation 531.3.3 now states that RCD Type AC shall only be used to serve fixed equipment, where it is known Fire alarm and emergency lighting systems are required to be inspected in accordance with BS 5839 fire detection & alarm systems for buildings and BS 5266 Emergency lighting, code of practice for the emergency lighting of premises respectively.