Technical Standards
BS 7671 Quick Reference Guides
Essential field and exam reference tables covering inspection procedures, GS38 safety rules, and observation classifications.
Testing Procedures
BS 7671:2018+A4:2026 Chapter 64 / GN3 Section 2.7 Standard Inspection & Testing Sequence
Normative sequence of dead and live tests required under BS 7671 Regulation 643.1.
✓ Dead Test 1: Continuity of protective conductors (main & supplementary bonding)
✓ Dead Test 2: Continuity of ring final circuit conductors (r1, rn, r2)
✓ Dead Test 3: Insulation resistance (tested at 250V / 500V / 1000V DC)
✓ Dead Test 4: Polarity (dead continuity check)
✓ Dead Test 5: Earth electrode resistance (where applicable)
✓ Live Test 1: Polarity (live voltage check)
✓ Live Test 2: Earth fault loop impedance (Ze & Zs)
✓ Live Test 3: RCD trip times (1/2x, 1x, 5x, & manual test button)
✓ Live Test 4: Prospective fault current (Ipf / PFC)
✓ Live Test 5: Functional testing of switchgear and controls
Safety & Legislation
HSE Guidance Note GS38 / EAWR 1989 Regulation 14 Safe Isolation Procedure & GS38 Standards
HSE Guidance Note GS38 10-step safe isolation procedure for working dead safely.
✓ Step 1: Seek permission and notify affected persons
✓ Step 2: Identify the source of supply to be isolated
✓ Step 3: Isolate the supply (open main switch or MCB)
✓ Step 4: Secure the isolation (padlock / lock-out tag-out notice)
✓ Step 5: Select approved voltage indicator (GS38 compliant)
✓ Step 6: Test voltage indicator against a known proving unit
✓ Step 7: Test between all conductors (L-N, L-E, N-E)
✓ Step 8: Re-test voltage indicator against proving unit to confirm operation
✓ Step 9: Put warning notices in place
✓ Step 10: Begin work dead safely
Test Values
BS 7671:2018+A4:2026 Table 64 Minimum Insulation Resistance Values
Minimum required insulation resistance values and test voltages under BS 7671 Table 64.
✓ SELV & PELV circuits: Test voltage 250V DC -> Min resistance 0.5 MΩ
✓ Up to 500V (inc 230V/400V domestic/commercial): Test voltage 500V DC -> Min resistance 1.0 MΩ
✓ Above 500V: Test voltage 1000V DC -> Min resistance 1.0 MΩ
✓ Action limit: Any circuit reading < 2 MΩ should be investigated for insulation deterioration
Condition Reporting
BS 7671 Appendix 6 / GN3 Section 3 EICR Classification Codes (C1, C2, C3, FI)
Definitions and practical classification examples for EICR inspection reports.
✓ Code C1 (Danger Present): Risk of injury exists. Immediate remedial action required. EICR automatically UNSATISFACTORY.
✓ Code C2 (Potentially Dangerous): Urgent remedial action required. EICR automatically UNSATISFACTORY.
✓ Code C3 (Improvement Recommended): Does not comply with current standard but is not dangerous. SATISFACTORY report possible.
✓ Code FI (Further Investigation Required): Cannot fully inspect without delay. Automatic UNSATISFACTORY until investigated.