What are the minimum lux levels for emergency lighting?

BS 5266-1 specifies: Escape routes — minimum 1 lux on the centre line of the route (0.5 lux at the edges), with a uniformity ratio no greater than 40:1. Open areas (anti-panic lighting) — minimum 0.5 lux at floor level over the core area (excluding 0.5m border). High-risk task areas — minimum 10% of the normal maintained illuminance, but not less than 15 lux. These levels must be achieved within 5 seconds of supply failure (60 seconds to reach 50% for escape routes).

How long must emergency lighting batteries last?

BS 5266-1 requires a minimum duration of 3 hours for most premises. A 1-hour duration is only acceptable where the premises can be fully evacuated in that time AND re-occupation is not intended until the normal supply is restored. Sleeping accommodation always requires 3 hours. The battery must be able to provide the rated emergency lumens for the full duration after being maintained in a fully charged state.

Where must emergency luminaires be positioned?

Per BS 5266-1, emergency luminaires must be positioned: near each exit door, near stairs so each tread receives direct light, near any change in direction, near any change in floor level, at each intersection of corridors, outside and near each final exit, near each first aid point, near each fire alarm call point, near firefighting equipment, and near each change of direction on an escape route. Exit signs must be visible from the direction of approach.

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

Non-maintained: luminaires are off during normal conditions and only illuminate when the main supply fails. Maintained: luminaires are on at all times (powered by mains normally, switching to battery on failure). Sustained: luminaires contain two lamps — one for normal use, one for emergency. BS 5266-1 requires maintained or sustained operation in areas that may be used with the normal lighting off (e.g., cinemas, theatres).

How often must emergency lighting be tested?

BS 5266-1 requires: Daily — visual check that maintained luminaires are working. Monthly — brief functional test (simulating mains failure for enough time to confirm all luminaires illuminate, typically a few seconds). Annually — full rated duration test (3 hours or 1 hour as applicable) to verify batteries can sustain the luminaires for the full period. All tests must be recorded in a log book. Automatic test systems (DALI/self-test) are increasingly used.

TradeCalculator

Emergency Lighting Calculator — BS 5266

Calculate emergency luminaire count and spacing per BS 5266-1. Covers escape routes (1 lux), open areas (0.5 lux), and high-risk task areas (15 lux minimum).

Area Type

Determines minimum lux level

Luminaire Type

Emergency lumen output

Area Length

Length of escape route or room

Area Width

Width (max 2m for escape routes)

Mounting Height

Height of luminaire above floor

Battery Duration

3 hours standard per BS 5266-1

How We Calculate This

This calculator determines the number of emergency luminaires and their spacing using the lumen method adapted for emergency lighting per BS 5266-1.

Formula

Fittings = (Lux × Area) ÷ (Lumens per fitting × UF × MF)

BS 5266-1 Requirements

Escape routes: 1 lux centre line, 0.5 lux edges, 40:1 uniformity
Open areas: 0.5 lux at floor level
High-risk: 10% of normal illuminance, minimum 15 lux
Duration: 3 hours standard, 1 hour only where justified
Spacing: Max 2× mounting height for escape routes

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.