Electrical Testing & EICR: Periodic Inspection, Test Schedule & Documentation

Summary

Electrical testing is not just a compliance exercise — it's the only way to confirm that a completed or existing installation is safe to energise and use. In the UK, every new electrical installation must be tested and documented before it is put into service. Existing installations must be periodically inspected to catch deterioration, damage, modification errors, and outdated wiring before they cause fire or shock.

For tradespeople, understanding what testing involves matters for several reasons: you need to know when your work on an installation requires a test certificate, what tests you or a qualified electrician will perform, and how to read an EICR when assessing whether an installation is safe to work on.

The EICR replaced the Periodic Inspection Report (PIR) as the standard document format. Its coded grading system (C1, C2, C3, FI) is well known but frequently misapplied — understanding what each code means practically is important for advising customers.

Key Facts

• EIC (Electrical Installation Certificate) — issued for all new installations and significant alterations; signed by designer, constructor, and inspector
• MEIWC (Minor Electrical Installation Works Certificate) — for additions or alterations that do not include a new circuit; simpler format
• EICR (Electrical Installation Condition Report) — periodic inspection of existing installations; replaces PIR
• Recommended inspection intervals: domestic owner-occupied 10 years; domestic rental 5 years (now mandatory in England per The Electrical Safety Standards in the Private Rented Sector Regulations 2020); commercial 5 years; industrial 3 years
• Landlord obligation — EICR required at start of new tenancy; copy must be given to tenants within 28 days; copy to Local Housing Authority on request; remedial work within 28 days of report
• C1 (Danger present) — immediate risk of injury; must be made safe before the inspector leaves
• C2 (Potentially dangerous) — could become dangerous; urgent remedial action required
• C3 (Improvement recommended) — not dangerous but improvement would improve safety
• FI (Further investigation required) — deficiency identified but extent cannot be determined without further work
• Satisfactory/Unsatisfactory — overall assessment on EICR; any C1 or C2 = Unsatisfactory
• Test sequence — must be performed in prescribed order: 1) continuity, 2) insulation resistance, 3) polarity, 4) earth fault loop impedance, 5) RCD operation

Quick Reference Table

Detailed Guidance

Test Sequence — Why Order Matters

BS 7671 specifies tests must be carried out in sequence. The reason is safety and logic:

1. Continuity tests first — with installation de-energised, verify all CPCs are continuous before you rely on them. A broken CPC with insulation failure could mean shock risk when energised.
2. Insulation resistance — with all MCBs off and equipment disconnected, apply 500V DC between each conductor pair. A reading below 1MΩ indicates deterioration, damage, or contaminated cable/connections.
3. Polarity — verify that the phase conductor is connected to phase terminals throughout, that switches interrupt the phase, and that sockets are correctly polarised. Carried out de-energised using a continuity tester from the CU outwards.
4. Earth fault loop impedance — now energised, measure the complete fault loop at each socket and fixed connection point. Compare to BS 7671 Table 41.2 maximum values for the MCB type and rating.
5. RCD testing — using an RCD tester, verify that each RCD trips within the time limits at rated tripping current, half rated current, and five times rated current.

EICR Coding — Practical Application

C1 (Danger present) examples:

• Live parts accessible (exposed wires, missing knockouts, open consumer unit)
• Severe overheating evidence (scorched terminals, burn marks on conductors)
• No earth on a circuit (socket circuit with no CPC)
• Reversed live and earth

C2 (Potentially dangerous) examples:

• Missing main equipotential bonding (gas or water pipe not bonded)
• No RCD protection on socket circuits
• Damaged cable insulation (but no exposure yet)
• Overloaded circuit (cable undersized for protection device)
• Ring final incorrectly wired as two radials
• Outdated consumer unit (rewirable fuse board with no RCD)

C3 (Improvement recommended) examples:

• Older wiring in good condition but single-insulated
• Supplementary bonding absent in bathroom (where main bonding confirmed and circuits RCD protected)
• Lack of surge protection device (SPD)
• Mixed old and new cable colours without adequate labelling
• Absence of circuit schedule at consumer unit

FI (Further investigation) examples:

• Accessible loft or ceiling void where wiring cannot be inspected
• Circuits not accounted for on schedule (unknown additions)
• Wall chased cables where damage cannot be ruled out

Insulation Resistance — Common Issues

Minimum acceptable: 1MΩ per circuit at 500V DC for new or rewired installations. For older existing installations with equipment connected (where full disconnection is impractical), ≥0.5MΩ is the minimum but indicates investigation is warranted.

Failures are commonly caused by:

• Water ingress at outdoor fittings (socket, FCU, garden lighting)
• Damaged cable in chased walls (often from later drilling)
• Deteriorated PVC insulation (older installations, especially near heat sources)
• Contaminated connections in damp environments

If insulation resistance is low, disconnect individual circuits and re-test to isolate the problem circuit. Within each circuit, disconnect outlets one by one to locate the specific fault.

Earth Fault Loop Impedance — Reading the Results

Zs must not exceed the values in BS 7671 Table 41.2. Key values to memorise:

Measured Zs = Ze (external, from supply) + R1+R2 (internal circuit resistance). If Zs is marginal, check:

• CPC continuity is good (poor connections raise R2)
• Cable run is not excessively long
• Ze is normal for supply type (PME typically 0.1–0.35Ω)

RCD Testing

Every 30mA RCD must be tested:

• At rated current (I△n = 30mA): must trip in ≤300ms
• At half rated current (15mA): must NOT trip within 300ms (verify selectivity)
• At five times rated current (150mA): must trip in ≤40ms

Test in both positive and negative half-cycles (the tester does this automatically). Many modern RCBOs will show different trip times on positive vs negative half-cycles — both must be within limits.

The test button on the RCD is a functional check only — it does not verify the actual trip current or time.

Frequently Asked Questions

Can a gas engineer or kitchen fitter issue an EICR?

No. EICRs must only be issued by a qualified electrician who is competent to undertake inspection and testing. They should hold a recognised qualification (City & Guilds 2391-52 or equivalent) and be registered with a competent person scheme such as NICEIC or NAPIT. If you are a non-electrician tradesperson who notices obvious safety concerns during your work (live parts exposed, scorch marks), you should bring them to the customer's attention and recommend they get an electrical assessment.

What's the difference between an EIC and an EICR?

An EIC is issued at the end of new installation work — it's the "pass" certificate confirming the new installation has been tested and complies with BS 7671 at the time of completion. An EICR is issued after inspecting an existing installation and may identify C1/C2/C3 deficiencies. An EICR that is "Unsatisfactory" (has C1 or C2 codes) does not condemn the installation immediately but requires remediation.

How long is an EICR valid?

There is no expiry date on an EICR, but the report specifies the recommended interval for the next inspection. For private rental, the legal maximum is 5 years. The inspector may recommend a shorter interval based on installation condition.

Regulations & Standards

• BS 7671:2018+A2:2022 — 18th Edition Wiring Regulations; Part 6 and Appendix 6 (inspection and testing)

• IET Guidance Note 3 — Inspection and Testing (detailed procedures)

• The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 — Mandatory EICR for rental properties

• Approved Document P — Certification of new and altered installations

• NICEIC/NAPIT scheme rules — Certification formats for self-certifying operatives

• IET Guidance Note 3 — Inspection and Testing — IET Publishing

• MHCLG Electrical Safety Guidance — GOV.UK landlord guidance

• NICEIC EICR Guidance — Competent person scheme documentation

• Part P Guidance — GOV.UK

• consumer units — RCBO vs RCD boards, SPD requirements

• socket circuits — Ring continuity testing

• earthing bonding — Continuity testing of CPCs and bonding

• part p notifications — When notification is required

• landlord certificates — EICR as a landlord legal requirement