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: emergency lighting requirements by location
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.
What do the emergency lighting testing regulations require?
A monthly function test and an annual full duration test for the rated period, both recorded. The duty comes from the Fire Safety Order's requirement to maintain the measures; the standard sets out how, and the log book is the evidence.
What does local emergency lighting mean, against a central system?
It describes where the battery is. In a local, self contained system each luminaire carries its own battery and charger, so a failure affects one fitting, the wiring is ordinary and the maintenance is a fitting by fitting job. In a central battery system one battery bank feeds the whole installation through fire rated cabling, which is dearer to install, easier to monitor and cheaper to maintain over a large building because there is one set of cells to replace. The standards accept both. The choice is usually made on the size of the building and on who will maintain it, not on price alone.