Definition of Class 0, I, II and III Lamps
Lamps can be classified as Class 0, I, II or III according to their shock resistance type, and their definitions are as follows:
(1) Class 0 Lamps
Lamps that rely on basic insulation to prevent electric shock. This means that the accessible conductive parts of the lamp (if any) are not protected conductors in the fixed wiring of the facility, and if the basic insulation fails, they must depend on the environment.
(2) Class I Lamps
Lamps whose protection against electric shock depends not only on basic insulation, but also on additional safety measures. The accessible conductive parts are connected to the protective grounding conductor in the fixed wiring of the facility. If the basic insulation fails, the accessible conductive parts will not be charged.
(3) Class II Lamps
Lamps whose protection against electric shock depends not only on basic insulation, but also on additional safety measures, such as double insulation or reinforced insulation, and do not require grounding or installation condition protection.
(4) Class III Lamps
Protection against electric shock depends on the supply voltage being a safe extremely low voltage (SELV) and the lamp will not produce voltages higher than SELV.
