Emergency lighting is designed for use when mains-supplied primary lighting luminaires fail. For this reason, emergency lighting luminaires have to be supplied from an independent source of electric power.
Elementary problems of emergency lighting design
Emergency lighting is designed for use when mains-supplied primary lighting luminaires fail. For this reason, emergency lighting luminaires have to be supplied from an independent source of electric power.
Emergency lighting must comply with the requirements and parameters specified in PN-EN 1838 and PN-EN 50172. The main purpose of emergency lighting is to enable safe exit or evacuation of the premises where the mains supply fails.
As the efficiency of light sources tends to decrease with operation time, the luminaires get dirty and other factors affect the overall performance, it is recommended to design the luminous intensity at least at 1.25 times the level recommended in applicable standards. For the calculation of the luminous intensity of emergency escape lighting only direct illumination of the surface should be considered, without any light reflected in floors, walls or ceilings.
For normal activities to be carried out as usual stand-by lighting is provided.
If stand-by lighting is used as emergency escape lighting, the system should be compliant with the above-mentioned standards and any other standards applicable to the products and wiring used. If the illuminance provided by stand-by lighting is lower than the minimum illuminance level achieved with primary lighting, such lighting should only be used to ensure proper completion or interruption of activities.