What lux levels does BS 5266 require for emergency lighting?

BS 5266-1 requires 1 lux minimum on the centre line of escape routes at floor level, 0.5 lux minimum in open areas larger than 60m2 (anti-panic lighting), and 10% of normal illuminance or 15 lux minimum for high risk task areas. The uniformity ratio must not exceed 40:1 for escape routes and open areas, or 10:1 for high risk areas. These levels must be achieved within 60 seconds of mains failure.

How long must emergency lighting batteries last?

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.

What is the difference between maintained and non-maintained emergency lighting?

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.

Where must emergency light fittings be positioned?

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.

How often must emergency lighting be tested?

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.

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Emergency Lighting Layout Calculator

Calculate emergency lighting fitting quantities and spacing per BS 5266 for escape routes, open areas and high-risk zones.

Area Type

Type of area requiring emergency lighting

Fitting Output

Lumen output of emergency lighting fitting

Route Length / Area Length

Length of escape route or dimension

Route Width

Width of escape route or corridor

Open Area Size

Total area for open-area or high-risk calculation

Ceiling Height

Floor to ceiling height

How We Calculate This

This calculator determines the number of emergency lighting fittings and their spacing based on the area type, fitting output and BS 5266-1 lux requirements.

How it works

Area type: Escape routes need 1 lux, open areas 0.5 lux, high-risk zones 15 lux minimum.
Fitting output: Higher lumen output allows wider spacing between fittings.
Spacing formula: Based on lumen output, utilisation factor and required lux level at floor level.
Key positions: Fittings must be at exits, intersections, direction changes and stairways regardless of spacing.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.