About BS 7671:2018 (18th Edition)
BS 7671 is the British Standard for electrical installation safety, also known as the IET Wiring Regulations (18th Edition). It sets the requirements for the design, installation, testing, and verification of electrical installations in the UK.
Key Regulations Covered
- ✓ Part 4: Protection for safety (Chapter 41-44)
- ✓ Part 5: Selection and erection (Chapter 51-55)
- ✓ Part 6: Inspection and testing (Chapter 61-64)
- ✓ Appendices: Tables, diversity factors, test procedures
Our Calculators Help With
- ✓ Design: Correct sizing and protection selection
- ✓ Compliance: Meeting regulatory requirements
- ✓ Testing: Verification and certification
- ✓ Documentation: EICR and installation certificates
Important: These calculators are tools for initial design and verification. Final installations must be designed, installed, and tested by qualified electricians in accordance with BS 7671:2018+A2:2022.
Common BS 7671 Regulations Reference
Chapter 41 - Protection Against Electric Shock
Covers earthing, bonding, and automatic disconnection of supply
Chapter 43 - Overcurrent Protection
Requirements for circuit protection and conductor sizing
Chapter 52 - Selection and Erection
Cable sizing, voltage drop, and installation methods
Chapter 54 - Earthing Arrangements
Earthing and protective bonding conductor sizing
Available Calculators
Earthing & Bonding Calculator
Calculate main earthing, protective bonding, and CPC sizes using BS 7671 Table 54.7 & 54.8
Max Zs Calculator
Calculate maximum earth fault loop impedance per BS 7671 Table 41.3 for MCBs and fuses
Ring Final Circuit Calculator
Verify ring circuit design and calculate continuity test values per BS 7671 Appendix 15
Prospective Fault Current Calculator
Calculate PSCC and PEFC to determine breaking capacity requirements per Regulation 612.11
Diversity & Maximum Demand Calculator
Calculate maximum demand with diversity factors per BS 7671 Regulation 311.1 and Appendix 1
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