Understanding Electrical Inspection and Testing

Electrical Inspection and Testing
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Inspection and testing can refer to many different situations at all voltage levels. This blog focuses on electrical safety inspection and testing in relation to low voltage systems and includes requirements for electrical installations and also the in-service inspection and testing of electrical equipment.

What is electrical inspection and testing?

The intention of inspection and testing is to assist a Duty Holder to demonstrate that electrical systems are safely constructed and maintained to avoid electrical danger occurring. The frequency of it is decided by the Duty Holder and takes into account the recommendation of the designer (in the case of initial verification) or the inspecting engineer (for periodic and in-service inspection and testing).

Importance for electrical work

The need to undertake inspection and testing relates to the requirements of regulation 4 of the Electricity at Work Regulations 1989. Regulation 4(1) requires electrical systems to be of such construction so as to avoid danger. This is initial verification of electrical installations whereby inspection and testing confirms that both the designers intentions and the requirements of BS 7671 have been met. Work is certified, through an Electrical Installation Certificate or a Minor Works Certificate.

Regulation 4(2) requires electrical systems, including electrical installations and electrical equipment to be maintained, if danger would otherwise exist. Periodic inspection and testing of electrical installations verifies if existing maintenance programmes are effective and if the electrical installation is foreseeably safe for continued use. An Electrical Installation Condition Report is issued. For electrical equipment, in-service inspection and testing is undertaken and a report prepared. We often refer to this as Portable Appliance Testing.

Who is qualified to carry it out?

Person undertaking the electrical inspection and testing must be competent. This not only means that they should be trained (have knowledge) and experienced in the electrical safety principles and the equipment used, but they should have familiarity with the electrical system and the equipment connected to it. Furthermore, in the case of periodic inspection and testing, the inspecting engineer should be conversant with the current requirements and standards, and also the requirements and standards that were in force when work was originally completed. This is so that they can fully evaluate the safety of the system and its suitability for continued use, and the recommendations and observations identified.

In the case of initial verification, which includes certifying new electrical installations, alterations made to an existing electrical installation and additions made to an existing electrical installation, the signatories are certifying the design, construction and inspection and testing and full compliance of the work undertaken. Such certificate is ordinarily issued, and the electrical system put into service, only once all defects have been rectified and all test results have been verified as being within acceptable limits. For periodic inspection and testing, Electrical Installation Condition Reports can be signed and issued with defects in place, as the inspecting engineer is providing a professional opinion on the condition of an existing electrical installation and is making recommendation on improvements that should be made.

Initial verification requires all mandated inspection and testing to be completed in a set sequence to ensure that it is safe to put an electrical installation into service. Systems should never be energised until all inspections and the required dead tests have been completed and found to be satisfactory. On energisation, all remaining testing must be completed before that electrical installation is put into use.

On no account should electrical installations be energised and put into service before the initial verification process has been completed.

The extent of any periodic inspection and testing, and any permitted limitations should be agreed between the Duty Holder and the inspecting engineer before work commences. There may be a need to review the agreements as the work progresses, taking account of the results of the inspection and testing completed and any operational challenges that are identified. Although the sequence should be completed in as logical an order as possible, it is permitted to undertake the inspections and testing in the most appropriate sequence provided that safety is maintained. In some cases, prescribed tests may be omitted or adapted, provided that both the Duty Holder and the inspecting engineer are in agreement.

Test instruments should be suitable for the task, taking account of BS EN 61010 and BE EN 61557. Test leads should comply with HSE guidance document GS 38. The accuracy of test instruments must be verified, the easiest way of achieving this is to annually, or more frequently, have test instruments calibrated.

In addition to the legal requirements of ensuring that electrical systems remain safe, many insurance companies mandate inspection and testing programmes for both fixed wiring and electrical equipment, and the production of suitable certificates and reports before claims are processed. Discovering after a fire has occurred that insurance cover has been invalidated by failing to produce inspection and test records can prove to be very expensive.

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