First, we must ask ourselves, what is the point of emergency lighting?
Many think that it is just so that we can see if the lights go off, or if there is a fire and the lights go off, we can see the door to get out of the building. While this is in essence true, the point of emergency lighting is much deeper than that.
Consider a room, full of furniture and other obstacles, chairs, boxes, the cleaner’s vacuum and such like. Now imagine that room dark and the fire alarm going off, people panicking to get out as smoke starts to come in the room.
One small light over the door may not give enough light to adequately negotiate the movable objects that may be unseen and in the way.
Now imagine a person or persons in that room who are not familiar with the surroundings. A clear well-lit path is now even more essential.
Let us now take the scene up a level. All the occupants have vacated the building safely and the darkened room is now full of smoke making visibility of obstacles even harder to detect.
Running into the room now is a couple of fire fighters. How much more dangerous and life threatening now is their job if there is not sufficient emergency lighting?
Now we must look at where to site these escape lights.
We must ensure that there is plenty of light along the escape route. This will be done for you by a designer, but all manufacturers will provide light levels and spacing with their light fittings. A light level of 1 lux must be available at 1m height along the escape route.
Signage and running man pictures should indicate the escape routes and the final door exits. Junctions and change of direction on escape routes must be lit as well as change in floor level, such as stairs.
Escalators and lifts should have emergency lighting, even though in a fire these will not operate, they will still require adequate illumination in the event of power failure.
Toilets exceeding 8M square or rooms with no natural light along with control rooms, switch rooms and hazardous areas all require good emergency illumination.
This list is not exhaustive and care during the planning stage of a building must take escape and even good back up lighting into consideration.