Quick reference
The numbers you are expected to know
15 reference cards covering test and limiting values, classification and reporting, safe isolation and GS38, and the test sequences — each with the regulation or guidance behind it. Written against BS 7671:2018+A4:2026.
Test & limiting values
The numbers the 2391-52 expects you to apply correctly: insulation resistance, earth fault loop impedance, disconnection times and RCD operating times.
- Table 64 insulation resistance
- Maximum earth fault loop impedance (Zs)
- Disconnection times (Table 41.1, U₀ 230 V)
- RCD operating times
- RCD test currents and expected times
Classification & reporting
How observations are coded, how those codes drive the overall assessment, and which certificate or report is the correct document for the work.
- EICR classification codes
- Overall assessment rule
- Choosing EIC, EICR or MEIWC
Safe isolation & GS38
HSE Guidance Note GS38 requirements for test probes, leads and voltage indicators, and the prove–test–prove sequence that proves a circuit dead.
- Test probe requirements
- Fusing of test leads and probes
- Voltage indicator CAT ratings
- Prove–test–prove sequence
Test sequence & procedure
The order tests are carried out in, and why that order matters — dead tests before energising, live tests after.
- Dead tests, in order
- Live tests, in order
- Test instrument accuracy and requirements
Bookmarkable in the app
The same 15 cards are in the app, where you can bookmark the ones you keep coming back to and reach them offline on site.
