Electrical Inspection Checklist: What Electricians Verify Before and After Installation

Quick Answer: Every notifiable installation must be verified by inspection (visual checks of compliance with BS 7671) and by testing (eight prescribed measurements documented on either an Electrical Installation Certificate, Minor Works Certificate, or EICR). The current minimum test sequence is continuity of protective conductors, continuity of ring final circuit conductors, insulation resistance, polarity, earth fault loop impedance (Zs/Ze), prospective fault current (Ipf), RCD operation, and functional testing.

Summary

The inspection-and-test routine in BS 7671 is not optional paperwork — it is the legal verification that a circuit will disconnect within the required time under fault conditions. Every figure on an EIC is the result of a specific test that mirrors an attribute the regulations require, and every visual checkpoint is there because it has been a frequent cause of failure or fire in past installations.

The structure is straightforward: a planned inspection during installation (covering the parts that will be hidden), a complete inspection on completion (covering the parts that remain visible and accessible), then a documented test sequence using a Multi-Function Tester (MFT). Outputs are recorded on:

• Electrical Installation Certificate (EIC) — for new installations and major alterations.
• Minor Electrical Installation Works Certificate (MEIWC) — for minor additions or alterations.
• Electrical Installation Condition Report (EICR) — for periodic inspection of existing installations.

For homeowners and clients, the test certificate is the proof that the electrician's work is electrically safe. Keep it with the property documents — it is referenced during conveyancing and required for landlord licensing under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020.

Key Facts

• BS 7671 Part 6 governs inspection and testing — Chapter 64 (initial verification) and Chapter 65 (periodic inspection and testing).
• Required test sequence — continuity of protective conductors, continuity of ring final conductors, insulation resistance, polarity, earth fault loop impedance, prospective fault current, RCD operation, functional checks.
• Insulation resistance — minimum 1 MΩ for SELV/PELV; 1 MΩ for LV up to 500 V; test at 250 V DC for ELV, 500 V DC for LV (Regulation 643.3.2).
• Continuity of protective conductors — tested live-to-live with a low-resistance ohmmeter; values typically below 0.5 Ω for short runs.
• Ring final circuit continuity — three measurements (R1+R2 at each socket; R1+Rn at the loop ends) confirm ring integrity and detect break or T-spur.
• Earth fault loop impedance (Zs) — measured live-to-earth at the most distant point of each circuit; must satisfy disconnection time per Regulation 411.3.2 (0.4 s for sockets up to 32 A on TN; 0.2 s on TT).
• Prospective fault current (Ipf) — measured at the origin and used to select adequate fault protection rating for breakers and busbars.
• RCD operation — push button test plus instrument test at IΔn (rated tripping current) and 5 × IΔn; must trip within 300 ms at IΔn (40 ms at 5 × IΔn for general-purpose RCDs).
• EICR codes — C1 (danger present, immediate action), C2 (potentially dangerous, urgent remedial action), C3 (improvement recommended), FI (further investigation required).
• EICR frequency — every 10 years for owner-occupied dwellings (recommended), every 5 years for rented dwellings (legally required since 1 April 2021), every 1–5 years for commercial premises depending on use.
• Test instruments — calibration certificate within 12 months, calibration interval declared on the certificate.
• Photographic record — increasingly common to attach photos of the consumer unit, accessories and earthing arrangement to the certificate; not legally required but useful evidence.
• Schedule of inspections — the tick-box section of the EIC; every entry is a Yes/No/N/A; comments column for any non-compliant items.
• Schedule of test results — circuit-by-circuit table with each measured value entered; cross-checked with circuit chart in CU.
• Special locations — bathrooms (Section 701), swimming pools (702), agricultural premises (705), construction sites (704), medical (710), saunas (703), exhibitions (711), EV (722), PV (712) — each has additional inspection points.
• Competent Person Scheme — Part P notifications via NICEIC/NAPIT/Stroma/ELECSA Competent Person Schemes self-certify Building Control compliance.

Quick Reference Table

Detailed Guidance

Pre-installation inspection

Before energisation, verify:

• Cable size matches the design current and voltage drop calculations.
• Conductors are correctly labelled and identifiable.
• Glanding and termination of armoured cables uses the manufacturer-specified gland with earth tag.
• Protective conductors are present, correctly sized (≥ 0.5 × cable CSA where rated to that method, or to the table in Section 543).
• All accessories, distribution boards and consumer units are appropriate for their location (IP rating, mechanical protection, accessibility).
• Earthing system identified (TN-C-S, TN-S, TT) and bonding installed to the main earthing terminal at the right size (typically 10 mm² for main protective bonding to gas, water, structural metalwork).

Live verification — the eight tests

The order matters. Continuity tests are dead-circuit tests with the supply isolated and the fuse or MCB removed; they verify that protective conductors and ring conductors are intact. Insulation resistance is performed on the dead circuit at full test voltage. Polarity is dead-tested. Only after these dead tests pass does the installation get energised for live tests (Zs, Ipf, RCD, functional).

1. Continuity of protective conductors. The R2 measurement: continuity of the CPC from the main earthing terminal to the furthest point on each circuit. Null the test leads first. A typical bedroom circuit gives R2 of 0.3–0.5 Ω; if the reading is significantly higher, suspect a loose terminal or a broken CPC.

2. Continuity of ring final circuit. Three steps: end-to-end continuity of L, N and CPC at the consumer unit (with all accessories disconnected); cross-connection to verify the ring forms a loop; R1+Rn check at the midpoint to confirm even loop resistance. The test reveals broken rings, T-spurs, and accidentally cross-connected rings — all common failure modes.

3. Insulation resistance. With circuits dead and fully isolated, apply 500 V DC between live conductors and between live conductors and earth. The reading must exceed 1 MΩ; in practice, healthy circuits read several hundred MΩ to "out of range." Low values indicate damaged insulation, neutral-earth contact, or appliances left connected.

4. Polarity. Dead-test confirms that L and N are not swapped at any accessory or that the protective device is in the live conductor. A polarity reverse on a single light fitting is a common minor failure on existing installations.

5. Earth fault loop impedance (Zs). Live test using a loop tester. Measure at the most distant point on each circuit. Compare with the maximum permitted Zs for the protective device per Tables 41.2/41.3/41.4 of BS 7671. For example, a 32 A B-curve MCB has a maximum Zs of 1.37 Ω (Table 41.3) for 0.4 s disconnection time on a 230 V TN supply.

6. Prospective fault current. Measured at the origin of the installation; ensures the maximum fault current does not exceed the breaking capacity of the installed protective devices (typically 6 kA or 10 kA for domestic).

7. RCD operation. Test at IΔn (must trip within 300 ms for general-purpose Type AC) and at 5 × IΔn (must trip within 40 ms). Type A and Type B RCDs have different tripping times for DC components — make sure the tester is set to match.

8. Functional testing. Operate every switch, push button, lighting circuit, RCD test button, and any safety service to confirm correct function. Verify the circuit chart matches the actual circuit on the breaker (a common error after consumer unit changes).

EICR — what gets coded and why

Periodic inspection on existing installations uses the same test sequence but with different output coding. Each item observed gets one of:

• C1 — Danger present. Immediate action required. Examples: missing earthing on a metal accessory, exposed live conductors, severely damaged consumer unit.
• C2 — Potentially dangerous. Urgent remedial action required. Examples: high Zs values (loop impedance fail), missing RCD on a circuit that requires one, no main earthing terminal, no main protective bonding.
• C3 — Improvement recommended. Not dangerous but below current standards. Examples: lack of SPDs (compliance is for new work, but C3 noted on EICR), older hardware that still functions, non-compliant cable colours predating 2006.
• FI — Further investigation required. The inspector cannot determine the condition without further work (e.g. concealed cables of unknown route, suspected hidden faults).

A C1 or C2 makes the EICR "unsatisfactory" and the installation cannot be deemed safe. C3 alone is "satisfactory." In rented properties, C1 and C2 items must be remediated within 28 days under the Electrical Safety Standards Regulations 2020.

Special locations — extra inspection points

• Bathroom (Section 701) — supplementary equipotential bonding (legacy installations); verification of zone-appropriate IP ratings; pull-cord switching; 30 mA RCD on all bathroom circuits.
• Swimming pool (Section 702) — SELV in zone 0; supplementary bonding to all metalwork in the area; isolation transformer or RCD per zone.
• Agricultural premises (Section 705) — equipotential bonding; cable mechanical protection from livestock; specific RCD requirements.
• EV charging (Section 722) — Type A or Type B RCD selection; protection for accessible metalwork; correct earthing system (TN-C-S restrictions).
• PV (Section 712) — DC isolator inspection; AC and DC labelling; earthing of frames per manufacturer.

Documentation and certificates

The EIC is not just paperwork — it transfers liability between the designer, installer, and inspector. Each section is signed by the named individual responsible. Mistakes in signing (e.g. one person signing all three columns when they did not personally do the design) are common and significantly reduce the legal weight of the certificate.

The schedule of test results lists every circuit and the eight test values. A blank cell or "N/A" without good reason is a warning sign on a third-party review.

Consumer-facing question — "do I need an EICR before selling my house?"

There is no legal requirement for an EICR to sell a home, but conveyancing solicitors increasingly request one in the property pack. A satisfactory EICR is reassurance for buyers and can prevent late-stage price negotiation. For landlords, the EICR is a legal requirement under the 2020 Regulations — every tenancy in England must have a satisfactory EICR no older than 5 years.

Frequently Asked Questions

How long is an EICR valid?

EICRs recommend a re-test interval based on the property type and use; for owner-occupied homes, typically 10 years. For rented homes, 5 years is the legal maximum under the 2020 Regulations.

What does it cost to get an EICR?

Typical domestic EICR cost ranges from £150 for a small flat to £350 for a large family home with multiple circuits. Commercial and industrial premises range from £350 to several thousand depending on size and complexity.

Can I do a DIY inspection?

Visual inspection (looking at accessories, earthing terminals, fuse box) is fine for basic understanding. Live electrical testing requires an MFT, calibration, training and competence. The output is also only legally meaningful when issued by a competent person.

What is "competent" person?

A person with the qualifications, experience and equipment to undertake the work safely and to certify it. Membership of NICEIC, NAPIT, Stroma or ELECSA Competent Person Schemes is the standard route, with City & Guilds 2391 (Inspection & Testing) the typical qualification for inspectors.

My EICR has lots of C3 items — is that bad?

C3 items are improvement recommendations, not safety failures. A 1980s installation will have many C3 items relative to a 2024 installation simply because standards evolve. The EICR is "satisfactory" provided there are no C1, C2, or FI items.

Regulations & Standards

• BS 7671:2018+A2:2022 — Requirements for Electrical Installations; Part 6 (Inspection and Testing), Chapters 64 and 65.

• The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 — duty on landlords to obtain a satisfactory EICR every 5 years.

• Building Regulations 2010, Approved Document P — defines notifiable electrical work in dwellings.

• IET Guidance Note 3 (Inspection & Testing) — practical inspection guidance, current edition.

• City & Guilds 2391 / 2392 / 2394 / 2395 — qualifications for initial verification and periodic inspection.

• HSE Electricity at Work Regulations 1989 — overarching duty to maintain electrical systems in safe condition.

• Electrical Safety First — EICR information — consumer-facing guide to inspection certificates.

• NICEIC Competent Person Scheme — installer registration and competent person criteria.

• gov.uk — landlord guide to electrical safety — statutory duty for rented homes.

• HSE — Electricity at Work Regulations — workplace electrical safety duties.

• consumer unit specification — what gets inspected first — the inspection target on most domestic notifiable works.

• SPD requirements under Amendment 2 — newer inspection point introduced in 2022.

• earthing arrangements and bonding tests — the basis for Zs measurement.

• cable sizing and verification — how design current relates to test results.