Question 1

How many emergency lights do I need per room?

Accepted Answer

The number depends on the zone type, room dimensions, and ceiling height. For escape routes up to 2m wide, luminaires must achieve 1 lux along the centre line with spacing no greater than 4 times the mounting height above the floor. For open areas requiring 0.5 lux, the spacing is typically 2 times the mounting height for adequate uniformity. This calculator determines the exact count from your room dimensions.

Question 2

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

Accepted Answer

Maintained (M) luminaires are lit at all times -- they operate as normal lighting and switch to battery when mains power fails. Non-maintained (NM) luminaires are off during normal conditions and only illuminate on mains failure. Maintained mode is required in places of entertainment (cinemas, theatres) and is recommended for areas where lighting may be dimmed. Non-maintained is standard for most commercial and industrial premises.

Question 3

When is 3-hour emergency lighting duration required?

Accepted Answer

Three-hour duration is required for sleeping risk premises (hotels, hostels, residential care homes), underground car parks with no daylight, premises that are not immediately evacuated (e.g. hospitals), and certain public buildings specified by the fire risk assessment. Standard commercial and industrial premises typically require 1-hour duration.

Question 4

Do I need emergency lighting in every room?

Accepted Answer

Not necessarily. BS 5266-1 requires emergency lighting on all escape routes, at every exit door, at changes of direction, stairways, intersections, near fire call points and fire-fighting equipment, in open areas over 60m square, in toilet facilities over 8m square, in lift cars, and in covered car parks. Individual offices under 60m square with a clear escape route may not need emergency lighting within the room itself.

Question 5

How often must emergency lighting be tested?

Accepted Answer

BS 5266-1 requires a monthly functional test (simulating mains failure for long enough to verify illumination, typically a few seconds for self-contained units) and an annual full-duration test where the system runs for the full rated period (1 or 3 hours). Results must be recorded in a log book. Automatic test systems can perform monthly tests without manual intervention.

Question 6

What is the difference between self-contained and central battery emergency lighting?

Accepted Answer

Self-contained luminaires each have their own battery and charging circuit -- they are independent units that switch on when local mains fails. Central battery systems use a single large battery pack that powers all luminaires via fire-resistant cabling. Self-contained is simpler and cheaper for small installations. Central battery is more efficient for large buildings, easier to maintain, and avoids the environmental issue of disposing many small batteries.

Question 7

Where must exit signs be placed?

Accepted Answer

Exit signs must be placed at every final exit (externally illuminated or internally illuminated), at every door on an escape route, and at points where it is necessary to indicate the direction of the escape route. Exit signs must be visible from a distance of at least 25m for externally illuminated signs, or according to the sign height calculation for internally illuminated signs (viewing distance = sign height x 100 for internally lit).

Question 8

Can LED emergency luminaires replace fluorescent ones?

Accepted Answer

Yes, LED emergency luminaires are now the industry standard, offering significantly longer battery life (typically 50,000+ hours vs 8,000 for fluorescent), lower power consumption (meaning smaller batteries for the same duration), and reduced maintenance. When replacing, ensure the LED unit provides at least the same lumen output as the original and complies with BS EN 60598-2-22 for emergency lighting luminaires.

Zone Type	Min Lux	Spacing Rule	Notes
Escape route (up to 2m wide)	1 lux	4x mounting height	Centre line and 50% on central band
Open area (anti-panic)	0.5 lux	2x mounting height	Excludes 0.5m border strip
High risk task area	15 lux min	Per design	Or 10% of normal illuminance if greater

Emergency Lighting Calculator

How This Calculator Works

Quick Reference -- Illuminance Requirements

Practical Notes

Frequently Asked Questions