Protection class I, II, III
Technical definitions in accordance with the regulation EN 5144 are applied here.
Protection class I
Tools belonging to this class contain one or more parts which are equipped with basic safety insulation and which need to be earthed in certain cases.
Protection class II
Tools in protection class II are completely insulated by a special insulation. They do not require earthing.
Protection class III
Tools belonging to protection class III are intended for connection to a LV (low voltage) supply network.
(See also Electrical safety)