Emergency lighting is lighting for an emergency situation when the main power supply is cut and normal illumination fails due to a fire or a power cut leading to sudden darkness and a possible danger to the occupants.  The main reason for installing an emergency lighting system is to enable the building to meet fire safety legislation and Building Regulations (Part B) in a way that is visually acceptable and meets the user’s needs for ease of operation and maintenance.
The specific British Standard (BS 5266-1: 2011) embraces residential hotels, clubs, hospitals, nursing homes, schools and colleges, licensed premises, offices, museums, shops, multi-storey dwellings, etc.

The Health and Safety (Safety Signs and Signals) Regulations 1996
This regulation requires the adequate provision of signs protected by emergency lighting. It details that signs should be located at all final exits and also on the escape routes at any location where the route may be in doubt.

Landlords and Tenanted Apartment Blocks
More information can be found here: http://www.safelincs.co.uk/fire-safety-information-for-landlords/