Protection classes
 
Protective measures are needed to ensure the electrical safety of luminaires. It is important, for example, that exposed metal parts cannot become live if the luminaire develops an electrical fault. Protection classes indicate the measures taken:
 

Protection class	Symbol	Protective measures
I		All the exposed metal parts are connected to one another and to the protective earth conductor.
II		The luminaire is insulated in such a way that there are no exposed metal parts that can carry current. There is no protective earth conductor.
III		The luminaire is operated on low voltages of 42 V or less supplied by a safety transformer or battery.