An EICR can contain plausible readings and still give a misleading account of the installation. The circuit references, limitations, observation codes and overall assessment have to agree.
Vulcan Works Electrical Services’ walkthrough covers a domestic installation with several distribution boards. Some details need correcting. This guide follows BS 7671:2018+A4:2026, including the revised treatment of further investigation.
Start with the purpose and extent
Regulation 651.1 concerns whether an existing installation remains satisfactory for continued service; 653.1 requires the condition report, following the Appendix 6 model.
Record the client, installation address, reason for inspection, inspection dates, estimated wiring age and available records. Unavailable records do not prove that nobody previously inspected the installation.
New work needs its own certification. EIC, Minor Works or EICR: Which Document Do You Issue? explains the distinction. The video excludes recently installed garage work covered by an EIC. Such an exclusion must be agreed and identified precisely; having an EIC does not automatically remove that work from an inspection of the whole installation.
Make limitations specific
The presenter says:
“There were no records available.”
Record this separately from limitations caused by inaccessible equipment.
Under 653.1 and the Appendix 6 model EICR, identify the extent, agreed limitations, reasons and person agreeing them. Record operational limitations discovered during the visit too.
Avoid a blanket “loft not inspected” when electrical equipment in an accessible roof space could be examined. Concealed cable routes may be inaccessible without opening the building fabric; accessible fittings are a separate matter.
A known defect cannot disappear into a limitation. Nor does being under a floor automatically reduce a dangerous cable condition to C3. Describe the evidence and assess the actual risk.
Record the supply and board arrangement
The walkthrough records TN-C-S, single-phase AC, 230 V, 50 Hz and prospective fault current of 0.739 kA. That last figure is 739 A: keep the units straight.
Record the verified supply protective device, means of earthing, main switch, earthing conductor and protective bonding details. A 100 A main-switch rating does not establish the cut-out fuse rating. Do not remove seals to obtain missing information.
For a single-phase supply, record the higher of PSCC and PEFC as prospective fault current. Regulation 643.7.3.201 permits measurement, calculation or another valid method; identify how the value was obtained. Compare it with device breaking capacity under 434.5.1, including any verified backup protection.
Give each board a unique reference and location. Identify DB2’s supply circuit on DB1, consistently across the schedules.
Test safely before completing the results
Section 643 provides the test methods used where appropriate during periodic inspection. For the circuits discussed, the sequence is:
- Inspect, identify supplies, isolate, lock off and prove dead.
- Verify protective-conductor continuity and ring-final conductor continuity.
- Test insulation resistance, then complete dead polarity verification.
- After satisfactory dead tests, verify supply polarity and characteristics before energising for necessary circuit loop, RCD and functional tests.
Continuity precedes insulation resistance so the protective conductor used as the test reference is known to be continuous. Dead tests establish whether energising is safe.
Use suitable voltage indicators and probes in accordance with HSE GS38, proving the indicator before and after proving dead. Live testing must meet Electricity at Work Regulations 1989, Regulation 14. Our test-sequence guide explains the order.
Keep Ze, Zs and board impedance distinct
The video attributes an increased Ze to a long parallel bonding path. That explanation is wrong: an additional parallel return path normally reduces measured loop impedance.
For a true Ze measurement, exclude installation parallel paths. Keep the installation safely isolated while the necessary upstream live supply test is performed, and reconnect protective conductors before restoring its supply. Disconnecting earthing while leaving the installation energised is bad practice.
On TN-C-S, isolation alone does not remove the risk of imported neutral current. Check for diverted current before disconnecting earthing or bonding; the IET’s neutral-current guidance explains the hazard.
Under 643.7.3.1, Zs may be measured or determined by another method. Ze + (R1 + R2) is calculated Zs; declare the calculation in the remarks rather than presenting it as a direct measurement. See the earth fault loop path explained.
At DB2, include its feeder impedance. Using the video’s figures:
- Origin Ze: 0.33 Ω
- Feeder R1 + R2: 0.10 Ω
- Calculated loop impedance at DB2: 0.43 Ω
- DB2 lighting R1 + R2: 0.53 Ω
- Calculated lighting Zs: 0.96 Ω
The video’s 0.86 Ω omits the feeder contribution. Boards being on opposite sides of a wall does not justify ignoring it.
Use the correct maximum Zs
The video uses temperature-adjusted guidance values. These differ from the values in Table 41.3.
| Type B BS EN 60898 circuit-breaker | Table 41.3 maximum Zs | 0.8 × tabulated value, rounded |
|---|---|---|
| 6 A | 7.28 Ω | 5.82 Ω |
| 16 A | 2.73 Ω | 2.18 Ω |
| 32 A | 1.37 Ω | 1.10 Ω |
| 40 A | 1.09 Ω | 0.87 Ω |
The Appendix 3 factor allows for conductor resistance increasing with temperature. If using On-Site Guide or Guidance Note 3 limits, identify the source; do not apply 0.8 again. The IET’s explanation of maximum Zs values covers this distinction.
Select the disconnection time first. Table 41.1 gives 0.4 s for the relevant TN final circuits at 230 V; TN distribution circuits may use 5 s under 411.3.2.3. Do not copy 0.4 s into every row automatically.
Enter continuity, insulation and RCD results honestly
Record actual circuit construction, conductor sizes, protective devices and reference methods. Table 4A2 of Appendix 4 distinguishes installation methods; “in a wall or ceiling” does not establish Method 102.
For ring finals, 643.2.1 requires conductor continuity verification. Record measured r1, rn and r2. The kitchen values, 0.34 Ω, 0.34 Ω and 0.59 Ω, predict approximately (0.34 + 0.59) ÷ 4 = 0.2325 Ω during the line–CPC cross-connection test. Compare readings around the circuit and record the highest measured R1 + R2, including spurs. Multiplying r1 by 1.67 is a sense check, not a substitute for measuring r2.
For ordinary 230 V circuits, 643.3.2 and Table 64 specify 500 V DC and a minimum 1 MΩ. Disconnect equipment that could be damaged or affect the reading. If disconnection is not reasonably practicable, the affected circuit may be tested at 250 V DC, still with a 1 MΩ minimum. Record the reason and test arrangement. USB sockets do not automatically justify reducing every circuit’s test voltage. IET inspection and testing FAQs confirm this.
For RCDs, identify the actual device protecting each circuit. Under 643.7.1 and 643.8, the verification test uses AC at IΔn; general non-delay devices must operate within 300 ms. Record the current, operating time and test-button outcome. The old requirement for a five-times test was removed; two unlabelled trip times prove little. IET RCD-testing guidance explains the change.
Leaving faulty exterior-lighting results blank is poor reporting. Record what was obtained, what prevented completion, the circuit’s status and the associated observation.
Match observations to the overall assessment
Use the inspection schedule’s legend: N/A means genuinely inapplicable; LIM records a limitation. Neither replaces coding a defect.
| Code | Meaning under the Amendment 4 model form | Effect on overall assessment |
|---|---|---|
| C1 | Danger present; immediate remedial action necessary | Unsatisfactory |
| C2 | Potentially dangerous; urgent remedial action necessary | Unsatisfactory |
| C3 | Improvement recommended | Advisory |
| FI | Further investigation is advised | Advisory |
Amendment 4 makes FI advisory. The video’s statement that FI automatically fails the report is outdated. The IET’s Amendment 4 explanation confirms this. Do not use FI to soften a demonstrated C1 or C2 defect.
The video’s automatic C2 for separate cable entries also needs reassessment against 521.5.1, the assembly standard and manufacturer’s instructions. Separate complete cables through different holes are not equivalent to separating individual AC conductors with steel. Describe the actual arrangement and hazard before coding it.
Finish with a complete, signed report
Attach the inspection, circuit-details and test-results schedules, with matching report references, dates and declarations. Include recipient guidance under 653.2.
Under 652.1 and 653.4, give a justified next-inspection date. This does not postpone urgent remedial action. An unsatisfactory EICR remains a valid report: retain it, certify remedial work appropriately and document verification of the observations addressed.
How 2391 Prep Fits Into This
2391 Inspection & Testing Pro has 556 practice questions across 7 subject areas, including Certification and Reporting, Periodic Inspection, Test Procedures and Fault Coding. Its 4 working calculators include Maximum Zs and Ring Final Circuit; it also provides 15 quick reference cards and 6 field tools.
City & Guilds 2391-52 is an OPEN BOOK exam: 60 questions, 120 minutes, 75% pass mark. Practise finding Chapter 65, Section 643, Tables 64 and 41.3, and Appendix 6 quickly, then check that your chosen rule matches the circuit and report.
