A complete UK guide to the three City & Guilds 2391 Inspection & Testing qualifications — what each one covers, which career paths need which qualification, and how to decide which is right for you.
Not enough time to read the full guide? Here's the shortest useful answer:
If you want the reasoning behind that, keep reading.
The 2391 series exists because inspection & testing splits into two very different workflows:
City & Guilds offers three separate qualifications so you can specialise in one, the other, or both:
Some training providers still refer to the older combined qualification (Level 3 Award in the Inspection, Testing and Certification of Electrical Installations, 2391-10 or 2391-52 depending on year). The current qualifications are 50, 51, and 52 — always ask your training provider for the exact code.
The 2391-50 covers the process of verifying new installations before they are energised. This includes visual inspection, testing sequence, and issuing an Electrical Installation Certificate (EIC).
2391-50 does NOT qualify you to carry out periodic inspection or issue EICRs. If a customer asks for an EICR, you'll need to sub-contract or refer.
The 2391-51 covers inspecting and testing existing installations, classifying defects, and producing accurate Electrical Installation Condition Reports (EICRs).
2391-51 does NOT qualify you to sign off new installations. If you're wiring a new circuit, you'll need someone with 2391-50 (or 52) to verify it.
The 2391-52 combines both initial verification AND periodic inspection into a single qualification. Most working UK electricians take this because it opens both types of work.
Everything in 2391-50 AND 2391-51 combined. You'll be tested on both initial verification and periodic inspection in the same exam.
Sitting 2391-50 AND 2391-51 separately typically costs £250-350 in exam fees and £900-1400 in training. Sitting 2391-52 combined typically costs £150-200 in exam fees and £500-800 in training. The combined qualification is cheaper AND more valuable.
| Feature | 2391-50 | 2391-51 | 2391-52 |
|---|---|---|---|
| Initial Verification (new installs) | ✓ Yes | ✗ No | ✓ Yes |
| Periodic Inspection / EICRs | ✗ No | ✓ Yes | ✓ Yes |
| Sign off own installations | ✓ Yes | ✗ No | ✓ Yes |
| Landlord rental testing | ✗ No | ✓ Yes | ✓ Yes |
| Number of questions | 40 | 40 | 60 |
| Exam duration | 90 min | 90 min | 120 min |
| Pass mark | 75% | 75% | 75% |
| Typical exam cost | £120-160 | £120-160 | £150-200 |
| Typical training cost | £400-700 | £400-700 | £500-800 |
Answer these three questions honestly:
Careers evolve. Even if you're currently only doing new installations, you might want to add EICR work in future as regulations tighten and demand grows. Taking 2391-52 now means you don't need to come back and add the periodic module later.
If budget is the deciding factor and you can only afford one exam, choose based on your primary work type. But do the maths: 2391-52 combined is only about £50-100 more than a single 2391-50 or 2391-51 — and it makes you significantly more employable.
Based on discussions with UK training centres (including our own at Learn Trade Skills in Cheshunt): around 80% of students choose 2391-52. It gives you the broadest employment options, costs marginally more than a single one, and future-proofs your qualifications.
The exception: apprentices whose employers specifically only need one type covered may be paid to sit just 2391-50 or 2391-51.
Whichever variant you sit, preparation approach is similar:
For 2391-51 and 2391-52, approximately 30-40% of the exam is scenario-based classification. You'll be given a real-world condition ("Cable found to be undersized for load") and asked whether it's C1, C2, C3 or FI. Practise dozens of these until it's automatic.
Know the test sequence cold — the exact order in which tests must be performed. This appears in almost every 2391 exam, often as a "which test first?" question.
Sequence for initial verification:
Open book doesn't mean easy — it means you need to know WHERE to look under time pressure. Practise mocks with BS 7671 and GN3 open on your desk, timing yourself strictly. Aim for consistent 75%+ before booking your real exam.
Amendment 4 changed several sections (particularly around EV charging and RCDs). Make sure your mock questions are updated for BS 7671:2018+A4:2026, not the older Brown Book.
Voltaris Academy has 640+ questions across 2391 combined, 2391-50 Initial Verification, and 2391-51 Periodic Inspection — all updated for Amendment 4 (Orange Book). Every answer includes the exact BS 7671 or GN3 reference. Try 10 questions free — no card required.
Start Free Trial →Yes — you can sit them separately over time. However, this typically costs significantly more overall (both training and exam fees) than sitting 2391-52 combined. Only do this if cash flow forces you to spread the cost.
Yes. 2391 is a Level 3 qualification that assumes you already know BS 7671 in depth. You must hold a valid current 18th Edition qualification before booking any 2391 course. If your 18th Edition is on Amendment 2 (Brown Book), consider updating to Amendment 4 (Orange Book / 2382-26) before starting 2391 — the exam references the current amendment.
Different, not necessarily harder. The 18th Edition tests your knowledge of BS 7671. The 2391 tests your judgement in applying that knowledge to real-world scenarios. Around half of 2391 questions are scenario-based — "Given these test results, what's the correct classification?" — which many candidates find harder than pure lookup questions.
Most training providers offer a 3-day or 5-day intensive course. Self-study typically takes 3-6 weeks alongside full-time work. The critical factor is practising enough scenario-based mock questions before the exam.
You can rebook and resit. Most test centres allow resits after a short cooling-off period (typically 2-4 weeks). You keep your training completion certificate; only the exam needs to be resat.
The qualification itself does not expire, but many trade bodies (NICEIC, NAPIT, ECA, Stroma) require periodic top-up training every 3-5 years. Check with your specific registration body.
The three 2391 qualifications exist because Inspection & Testing splits cleanly into two workflows: verifying new installations, and periodically inspecting existing ones. Choose based on the work you'll actually do:
If in doubt, take 2391-52. It costs only marginally more than a single specialism and future-proofs your career.
Related reading:
640+ mock exam questions across all three 2391 qualifications. Every answer explained with BS 7671 and GN3 references. 10 questions free — no card required.
Try Free Now →Voltaris Academy is an independent UK online mock exam platform for electricians. Our 2391 question bank covers all three variants (50, 51, 52) with detailed BS 7671 and IET Guidance Note 3 references. Free trial available — no card required.