Which British Standard covers requirements for initial verification and periodic inspection?

BS 7671 (IET Wiring Regulations) covers requirements for initial verification and periodic inspection and testing of electrical installations.

Who is legally qualified to carry out electrical inspection and testing?

Inspection and testing must be carried out by a competent person with the appropriate knowledge, skills, and experience.

A competent person with appropriate knowledge and experience

Anyone holding a current ECS card regardless of qualification

Only an electrician directly employed by the DNO

Any person over 18 who owns approved test equipment

What is the recommended inspection interval for industrial installations?

Industrial installations typically require inspection every 3 years due to the more demanding environment.

Free mock exam

C&G 2391-50 Mock Exam — Initial Verification

Free City & Guilds 2391-50 Initial Verification mock exam. 30 questions drawn from a 371-question bank covering initial verification to BS 7671: the full GN3 test sequence, safe isolation, continuity, insulation resistance, polarity, earth fault loop impedance, RCD testing, and certification with the Electrical Installation Certificate. Sitting the periodic unit instead? Use our 2391-51 mock exam — or the combined 2391 exam for the full 2391-52 syllabus.

Questions: 30
Time limit: 90 min
Pass mark: 70% · 21/30
Question bank: 371

Free, no sign-up. Retake as many times as you like — different questions each time.

Sample questions

01What does the term 'initial verification' refer to?
- AConfirmation of the supply characteristics provided by the distributor
- BInspection and testing of a new installation before energisation
- CThe periodic re-testing of an existing installation every ten years
- DThe first functional check carried out by the end user at handover
Why: Initial verification is the inspection and testing of a new installation or addition before being put into service.
02Which document must be provided after completing an initial verification?
- AAn Electrical Installation Condition Report
- BElectrical Installation Certificate
- CA Minor Electrical Installation Works Certificate
- DA PAT testing register
Why: An Electrical Installation Certificate must be provided after completing initial verification of a new installation.
03What is the correct order of testing during initial verification?
- AZs and RCD (live) first, then continuity, insulation and polarity
- BRCD and functional tests first, then all of the dead tests after
- CContinuity, insulation, polarity (dead), then Zs, RCD (live)
- DInsulation first, then Zs and RCD, then continuity and polarity
Why: Dead tests (continuity, insulation, polarity) are performed first, then live tests (Zs, RCD, functional).

Common questions

Is the C&G 2391-50 mock exam free?

Yes — 100% free, no sign-up needed. Questions are pulled at random from a substantial bank, with a worked explanation on every question after you submit.

Can I retake the mock exam?

Yes. Every attempt picks a different random selection and reshuffles the options, so each retake gives you genuinely new questions. No limit on retakes.

Does this count towards the real qualification?

No — this is independent practice material. To gain the actual qualification you need to sit the official assessment through an approved provider.