This is a small reference kept for the author's own use and left public because it costs nothing to do so. It is not affiliated with any standards body, manufacturer, testing house or trade association, and it reproduces no standard.
The material is deliberately narrow. Earthing arrangements, the vocabulary around them, and the handful of distinctions that people reliably get wrong — that is the whole scope. There is no intention to grow it into a general guide to electrical installation.
Descriptions here follow the common international classification. Where a national regulation differs, the national regulation governs. Nothing on these pages should be relied on for design, inspection, or certification work, and none of it substitutes for the current edition of the wiring rules applicable where the installation stands.
Pages are revised when something reads badly or turns out to be wrong. The footer of each page carries the month of the last review.