Terminology and abbreviations

PE and the earthing symbol

PE is the abbreviation for "protective earth" and has the same meaning as the earthing symbol

Earth, ground

This document uses the term “earth” which is the same as the U.S. term “ground”.

t.b.d.

Still to be defined, value or description will follow in due course.

DC 650 V

A figure displayed with the AC or DC before the value represents a nominal voltage with standard tolerances included.

Example:
DC 12 V refers to a 12 V battery, regardless of whether it is fully charged (13.7 Vdc) or discharged (10 Vdc).

400 Vdc

A figure with the unit (Vdc) at the end is a momentary figure without any additional.

may

A key word indicates flexibility of choice with no implied preference.

shall

A key word indicates a mandatory requirement.

should

A key word indicates flexibility of choice with a strongly preferred implementation.