Cable Sizing & Selection Calculators

Five essential calculators for cable selection and verification to BS 7671 IET Wiring Regulations. All calculations run in your browser — no data leaves your device.

Determine the minimum cable size based on design current, protective device rating, and correction factors from BS 7671 tables.

Disclaimer

These calculators use simplified reference data from BS 7671:2018+A2:2022 and the IET On-Site Guide. Results are for guidance and educational purposes only. Always verify against the full regulations and manufacturer data for your specific installation. Cable current-carrying capacities shown are for Reference Method C with thermoplastic (PVC) insulated cables unless otherwise stated.

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Complement your practical calculations with exam prep. Our app has 800+ practice questions with detailed explanations covering all parts of BS 7671.

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