Protection classes of luminaires and operating devices

The degree of insulation against electrical shock offered by luminaires and operating devices is split into two safety levels. These two safety barriers are designed to prevent any risk to safety in the event of a defective device.Luminaires and operating devices of protection class I provide protection against electrical shock solely using the base insulation and the safe connection of all exposed conductive parts to an earth conductor. Thus, should the base insulation fail, no exposed conductive parts can become live.Luminaires and operating devices of protection class II provide protection against electrical shock using both the base insulation and an additional or reinforced insulation. Protection class II products do not feature a connection to a protective earth conductor. (In special cases a device can feature or be required to feature a functional earth, e.g. for EMC reasons, or a continuation of the protective earth conductor in a luminaire.) The mounting conditions do not ensure any additional degree of protection, either.However, the connection of a protective earth conductor can also be permitted for protection class II luminaires in the following cases:
for EMC reasons – in such cases, it can be necessary to connect a function protection conductor to remain within EMC limiting values. The component manufacturer´s specifications regarding the individual operating devices must be observed during the construction of the luminaire. If an operating device is marked as containing a function protection conductor, the creepage and air clearance distances of the operating device connection must comply with the requirements of protection class II;
as an ignition aid for lamps – connecting a function protection conductor can be necessary as a capacitive ignition aid for lamps. In such cases the creepage and air clearance distances around the ignition aid within the luminaire and the function protection conductor connection terminal have to comply with the requirements of protection class II. The ignition behaviour of a lamp should be agreed with the manufacturer in these cases;
when wiring the protective conductor from the luminaire to another device. This installation point must comply with the creepage and air clearance distances stipulated in the luminaire standard.

Operating devices with double or reinforced insulation for installation in protection class II luminaires
Protection class II specifications have to be met by the luminaire along with its installed operating device. Both protection class I and class II ballasts can be installed. The design of the luminaire must be adapted to suit. This means that if a protection class I ballast is installed in a protection class II luminaire, the design of the luminaire has to be correspondingly sophisticated to ensure the creepage and air clearance distances can be met. On the other hand, using a protection class II ballast, only available as an independent ballast nowadays, will in most cases result in a need for too much technical effort and thus in high costs. Against this background, the standards contain special requirements for ballasts destined for installation in protection class II luminaires.These "double or reinforced insulation ballasts" permit technically and cost-effective construction of protection class II luminaires.
Protection class III luminaires provide protection against electrical shock by using Safety Extra Low Voltage (SELV). Luminaires of protection class III are not permitted to generate higher voltages than the Safety Extra Low Voltage (SELV).