Emergency lighting is required by law in general terms and specified in detail by standards. The law asks that emergency routes and exits requiring illumination are provided with emergency lighting of adequate intensity in case the lighting fails, and that workplaces have suitable and sufficient emergency lighting where a failure of artificial light would create danger. The standards say how that is achieved.
The legal duty
The fire safety order requires emergency routes and exits requiring illumination to be provided with emergency lighting of adequate intensity in case of failure of their normal lighting. The workplace regulations separately require suitable and sufficient emergency lighting in any room where people at work are specially exposed to danger if the artificial lighting fails. Both are outcome based and neither names a product.
What the standards cover
The design standard sets out where luminaires are required, the illuminance to be achieved on escape routes and in open areas, the duration, and the testing regime. Certain locations always need coverage: at each exit door, near each change of level, at every change of direction, at stairs, near fire fighting equipment and call points, in toilets over a certain size, and in plant rooms and lift cars.
The categories
Escape route lighting illuminates the defined route. Open area or anti panic lighting covers spaces where people would otherwise be unable to find a route at all. High risk task area lighting allows a person to shut down a dangerous process safely before leaving. Standby lighting, which lets normal activity continue, is not emergency lighting and is not required by fire law.
Maintained and non maintained
A maintained luminaire is lit all the time and stays lit on supply failure, which suits places of assembly where the normal lighting may be dimmed. A non maintained luminaire is dark until the supply fails. Both meet the requirement and the choice follows the use of the space rather than the standard.
Questions people ask about emergency lighting standards
Is there a legal duration for emergency lighting?
The law asks for adequacy. The standards set durations by application, and three hours is the common design duration in buildings where evacuation may be delayed or the building is used by the public.
Does every room need emergency lighting?
No. The escape routes and the locations the standard identifies need it, plus any area where a lighting failure would itself create danger.
What should an emergency lighting design leave behind?
A drawing showing every luminaire, the category of each area, the design illuminance, the duration, and a completion certificate. That is what the testing regime is then run against.