Theory

Key Concepts

UElectric VoltageBS 7671: Part 2 Definitions · Appendix 2IElectric CurrentBS 7671: 433.1.1 · Appendix 4RElectrical ResistanceBS 7671: Appendix 3 · 643.2PElectrical PowerBS 7671: 311.1 (maximum demand)ΩOhm's LawBS 7671: 411.4.4∑Kirchhoff's Laws∥Series and Parallel CircuitsBS 7671: 643.3⚠Safe IsolationBS 7671: 462 · 537.2

Protection Devices

CBCircuit Breaker (MCB)BS 7671: 411.3.2 · Table 41.3 · 533RCDResidual Current Device (RCD)BS 7671: 411.3.3 · 411.3.4 · 522.6.202 · 531.3.3 · 643.8RBRCBOBS 7671: 314.1 · 531.3.2AFArc Fault Detection DeviceBS 7671: 421.1.7 · 532.6SPSurge Protection DeviceBS 7671: 443.4 · 534FFusesBS 7671: 433.1.202 · Table 41.2

Cables and Wiring

≡Conductor Colour CodesBS 7671: Table 51 · 514.14.1mm²Cable SizingBS 7671: Appendix 4 · 523 · 433.1ΔVVoltage DropBS 7671: 525 · Appendix 4 section 6.4▤Cable Safe ZonesBS 7671: 522.6.202 · 522.6.203 · 522.6.204

Earthing and Bonding

⏚Earthing SystemsBS 7671: 312.2 · 411.4 · 411.5 · 542⊕Protective BondingBS 7671: 411.3.1.2 · 544.1 · Table 54.8 · 701.415.2

Special Locations (Part 7)

701Bathrooms (Section 701)BS 7671: 701.411.3.3 · 701.512.2 · 701.512.3EVEV Charging (Section 722)BS 7671: 722.311.201 · 722.411.4.1 · 722.531.3.101PVSolar PV & Prosumer (712 / 82)BS 7671: 712 · Chapter 82 · 530.3.201 · Chapter 57 (A4)710Medical Locations (Section 710)BS 7671: 710 · 710.415.2 · Appendix 6 (A4 bonding schedule)PoEPower over Ethernet (Section 716)BS 7671: 716

New in Amendment 4 (2026)

A4Amendment 4 OverviewBS 7671: Chapter 57 · 716 · 710 · 531.3.3 · 537 · 551 · 722BATStationary Batteries (Chapter 57)BS 7671: Chapter 57 · Chapter 82 · 514.15FEFunctional Earthing for ICTBS 7671: Chapter 54 · 543.5 · Section 444

Inspection and Testing

✓Test SequenceBS 7671: 643.1 · 643.2 – 643.11 · Appendix 6MΩInsulation ResistanceBS 7671: 643.3 · Table 64◯Ring Final Circuit TestBS 7671: 643.2.1C1EICR Observation CodesBS 7671: 653 · Appendix 6

Study notes referencing BS 7671:2018+A4:2026 (current since A2/A3 were withdrawn on 15 Oct 2026). Always verify against the official IET publication.