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Fire alarm commissioning and electrical test tools on a workbench

Check end-of-line voltage

Cable Voltage Drop Calculator

Estimate copper loop resistance, voltage drop and device voltage at the circuit end.

Method context

BS 5839-1:2025 Clause 25 / BS 7671 conductor data

The implementation follows the current Swift calculator in the Fire Regs Pro project. It is an estimate for revision and preliminary checking.

Check before use: Confirm the current standard, project specification, manufacturer data, environmental derating and actual site measurements. A browser result is not a design certificate.