There are four ways of classifying luminaires according to the type of protection against electric shocks, the degree of protection against dust and humidity, the degree of protection against impacts and the material of the surface on which the luminaire is placed.
1. Classification according to the type of protection against electric shocks – the luminaires are classified according to their type of protection against electric shocks, in Class I, Class II and Class III.
Class I luminaire: Luminaire in which the protection against electric shocks does not fall exclusively on the main insulation, but includes an additional safety measure in the form of means of connecting the accessible conductive parts with a protective earth conductor, forming part of the fixed wiring of the installation, so that the accessible conductive parts cannot become dangerous in the event of a defect in the main insulation.
Class II luminaires:… more info in pdf. catalogue