Enter measured Zs, insulation resistance and RCD trip times and check each circuit against BS 7671.
Enter measured Zs, insulation resistance and RCD trip times and check each circuit against BS 7671 limits (18th Edition).
For each circuit, the checker compares the measured Zs against 80% of the BS 7671 tabulated maximum for the protective device (the 0.8 factor allows for the rise in resistance at operating temperature), checks the insulation resistance, and — where fitted — the RCD trip time against the 300 ms limit at IΔn. Add a row per circuit to audit a whole board against the 18th Edition.
Max Zs values, diversity factors, cable ratings, voltage drop — one printable page. Plus occasional emails with calculator updates and useful tips.