Emergency lighting is lighting for an emergency situation when the main power supply is suddenly fails. Without emergency lighting this could lead to sudden darkness and possible danger to occupants, either through physical danger or panic.
However, there are different types of emergency lights that vary in their power and lighting sources.
Maintained Mode
The luminaire works in exactly the same way as a standard mains version, except when the power fails, it switches to battery powered emergency output. Normally the exit sign works as maintained mode but most of them are maintained and non-maintained switchable.
Non-Maintained Mode
The luminaire only lights in the event of a power failure as an emergency light source. The continual mains supply is only used to charge the battery.
Central Battery System
This is where the battery power for emergency lighting is situated at one to ensure safety power supply to all connected luminaires in the event of a power failure, whether they are maintained or non-maintained. All emergency luminaires’ LED indicator will show the battery’s charging status while there is a mains feed. When the power fails, the LED will switch off and the lamp will be illuminated by the battery. 
