Emergency Lighting Layout Calculator

BS EN 1838 requires 1 lux minimum on the centre line of escape routes up to 2m wide at floor level (with the central band — half the route width — at least 0.5 lux), 0.5 lux minimum in open/anti-panic areas larger than 60m² (excluding a 0.5m border), and 10% of the normal illuminance or 15 lux minimum — whichever is greater — for high-risk task areas. The ratio of maximum to minimum illuminance along escape routes and across open areas must not exceed 40:1, and high-risk task areas must achieve a uniformity Uo (minimum/average) of at least 0.1. 50% of the required illuminance must be reached within 5 seconds and full illuminance within 60 seconds of mains failure.

BS 5266-1 requires a minimum battery duration of 3 hours for most buildings. A 1-hour duration is only acceptable for premises that will be immediately evacuated and not re-occupied on mains failure (rare in practice). The 3-hour duration ensures lighting for evacuation, fire service operations and potential re-entry. Batteries must be regularly tested per BS 5266-8 with monthly function tests and annual full-duration tests.

Maintained emergency lighting operates at all times the building is occupied, with the lamp switching to battery power on mains failure. It is required in cinemas, theatres, licensed premises and venues open to the public. Non-maintained emergency lighting only illuminates on mains failure. It is suitable for workplaces where occupants are familiar with the building. Sustained fittings have a separate maintained lamp within the same fitting.

BS 5266-1 requires emergency luminaires within 2 metres of each exit door, at each intersection or junction of corridors, at each change of direction, at each stairway (to illuminate each flight), at each change of floor level, near each fire alarm call point, near each piece of firefighting equipment, near each first aid point, and at illuminated exit signs. Additional fittings are needed at regular spacing to achieve the required lux levels.

BS 5266-8 requires monthly function tests (switching to battery for a brief period and checking all fittings illuminate), quarterly checks of charging indicators, and an annual full-duration test (running on battery for the full rated period — typically 3 hours). All tests must be recorded in a log book. Automatic test systems can perform these tests and record results electronically.