Guidance Note 3: Inspection & Testing (Electrical Regulations)

Product Information

However, as referenced, this list is not exhaustive. Therefore, candidates will need to appropriately ensure they’re equipped with all fault eventualities prior to their assessment. Remember, this is simply a visual inspection! There is no opportunity for delegates to strip or examine any part of the instalment with their hands, or administer any other physical method of review. Fault finding within insulation resistance testing I would like to express my great appreciation to the following individuals for their valuable contributions to this article. It is often stated that the Wiring Regulations are not retrospective. Whilst this is true, it cannot be concluded that because something was acceptable in a previous edition of the Wiring Regulations it must be safe. For example, until 1966 it was acceptable to use a public water pipe as a means of earthing and Class I light fittings not to be earthed. That is not the case now and these should now be recorded as non-compliances. As indicated by Regulation 622.1, matters such as those listed, as well as the findings and recommendations of the previous periodic inspection, if any, should be taken into account when deciding on the period to the next inspection. Regular inspections of a particular frequency might be a requirement of a British Standard or a Code of Practice, such as is the case with some aspects of fire detection and fire alarms systems and emergency lighting installations.

Testing is an ancillary activity to inspection, rather than the converse. When carrying out the inspection and test, the inspector should compare the installation for conformity with the current edition of BS 7671 and record any identified non-compliances.Given that an RCD may take up to 0.3 seconds (300 ms) to disconnect it would appear at first glance that some disconnection times in Table 41.1 may not be achievable, for example, the maximum disconnection time for some final circuits on a TT earthing system is 0.2 seconds (200 ms), as shown in Table 3. However, a note under the table indicates that earth faults are of negligible impedance and it follows that disconnection times would be commensurately higher since a value of, for example, a residual current of 60 mA would be expected to provide a disconnection time of 150 ms and 40 ms (0.04 seconds) for a residual current of 150 mA, as shown in Table 2. Therefore, an operating time of 300 ms would be considered acceptable for a TT earthing system. C2: Potentially dangerous. Urgent remedial action is required. e.g. Zs value exceeding maximum permitted value.

Carrying out an inspection of electrical installations is a complex task, the person carrying out the inspection and testing is required to have comprehensive knowledge and experience of different types of electrical installations. The inspector will make an engineering judgement to determine the correct classification code. It is very important to note that Regulation 621.2 requires the installation to have a “ detailed examination” and that examination is to be “ supplemented by appropriate tests”. It is essential for persons engaged in inspection and testing to understand that the inspection is more important than the testing. C1: Danger present with a risk of injury. Immediate action should be taken to make these safe. e.g. Exposed live parts. The problem in "engineering" terms or any other terms for that matter is 1.4566666667 Ω does not equal 1.46 Ω.

Five-year Gold subscription

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. 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.