Emergency Lighting Calculator — BS 5266 Luminaire Layout

BS 5266-1 and BS EN 1838 specify different lux levels for different areas. Escape routes require minimum 1 lux at floor level. Under the current BS 5266-1:2025 / BS EN 1838:2024 editions this 1 lux now applies across the full width of the route (excluding a perimeter border whose width depends on the route width) — the older editions measured it only along the centre line. Open areas (anti-panic) need 0.5 lux horizontal at floor level across the core area, excluding a 0.5m perimeter border. High risk task areas need 10 percent of normal maintained illuminance or 15 lux minimum, whichever is greater. These are minimum maintained levels at floor level and apply when the normal lighting has failed.

BS 5266-1 requires a minimum battery duration of 1 hour for premises that can be evacuated immediately and are not used for sleeping. Sleeping premises (hotels, care homes, residential), entertainment venues, and complex buildings require 3 hours minimum battery duration. Most commercial installations default to 3 hours to provide a safety margin and cover the range of building uses. Self-contained LED emergency luminaires typically achieve 3 hours with a NiMH or LiFePO4 battery pack.

BS 5266-1 requires emergency luminaires at specific locations: near each exit door, at changes of direction in escape routes, at corridor intersections, outside each final exit, near stairs so each flight receives direct light, near fire alarm call points, within 2 metres of fire safety equipment (extinguishers, first aid points, fire alarm panel), in toilets and changing rooms over 8 square metres (lit as open areas), in lift cars where the lift forms part of the evacuation strategy in the fire risk assessment, and near safety signs. Exit signs must be illuminated at all exit points.

BS 5266-1 requires routine testing: a monthly functional test (a brief flick test to verify each luminaire operates) and an annual full-duration discharge test (1 or 3 hours depending on the rated duration) together with an annual visual inspection. BS 5266-1:2025 also adds a five-yearly photometric verification — measuring actual lux levels at floor level with a calibrated meter and confirming they still meet the design. All test results must be recorded in an emergency lighting log book. Automatic test systems using DALI or self-test luminaires can reduce the manual testing burden, but the annual and five-yearly checks are still required.

Maintained emergency luminaires are on all the time (acting as normal lighting and switching to battery power on mains failure). Non-maintained luminaires only switch on when the mains supply fails. Maintained mode is required in entertainment venues, theatres, cinemas and areas where normal lighting may be dimmed. Non-maintained is suitable for most offices, shops and escape routes where normal lighting is always on during occupation. BS 5266-1 provides guidance on selecting the appropriate mode for each area.