Electrical

Electrical calculators are only as useful as their scope is honest. Conductor sizing, voltage drop and load calculation are arithmetic with well-defined inputs, and they are done here to the standard's own method. What no calculator can do is inspect an installation, judge a termination, or know what else is already on the circuit — and those are the parts that decide whether work is safe.

Every page states which code or standard its method comes from and when that was last checked, because ampacity tables, correction factors and derating rules differ between jurisdictions and change between editions. Where a figure depends on a table, the table is named. Where a rule varies by market, the page says so instead of quietly picking one.