How this site works

What the calculators do, which code editions they follow, and how to check a result by hand.

Updated August 23, 2026

Every tool on this site is built the same way: the arithmetic lives in a small, separately tested module, and the page around it shows the tables that arithmetic came from. If the calculator ever disagrees with the table printed below it, the table wins — tell us and we will fix the code.

Which code edition

Calculators are labelled with the standard they follow:

NEC — NFPA 70, National Electrical Code (United States)
BS 7671 — IET Wiring Regulations (United Kingdom)
AS/NZS 3000 — Wiring Rules (Australia and New Zealand)

Adoption is local. A jurisdiction may still be on an earlier edition, or may have amended it. Check what your AHJ has actually adopted before you rely on a number.

Working without a signal

Reference tables, worked examples and FAQs are plain static HTML — they render even on a slow connection and stay readable if the calculator’s script never loads. The interactive part is the only piece that needs JavaScript.