Escape routes must be illuminated and designated according to legal provisions to facilitate required evacuation measures upon general power failure.
Safety lighting for escape routes
Safety sign luminaires on their own, however, are no replacement for safety lighting of escape routes. This requires special safety luminaires (emergency lights), possibly featuring their own energy source, or suitable assemblies within the general lighting luminaires.
Luminaires for safety lighting must be positioned at least 2 m above the floor.
The minimum illuminance of 1 lx (table 1.40) for safety lighting of escape routes applies to escape routes with up to 2 m width at the centre line of the escape route, directly on the floor. The middle area of the escape route with minimum half the route width (up to 1 m) must not be illuminated at less than 0.5 lx at any point. Escape routes exceeding 2 m of width must be treated as adjacent escape routes or illuminated with anti-panic lighting.
The minimum illuminance value of 1 lx which must not be undercut at any time (maintained value) applies for battery-operated luminaires up to the nominal operating time of 1 hour.
According to the same standard, elevator cars should be equipped with anti-panic lighting for cases of general power failure to avoid panic among people in the small space.
Emergency exits and the routes leading to them must be equipped with safety signs according to ISO 3864, or also according to DIN 4844 in Germany. These signs must be illuminated by an external light source or backlit by an internal light source and must be positioned visibly along the entire escape route up to safe areas.
High contrast between bright emergency lights and their background can cause significantly impaired vision. The limitation of physiological glare is therefore particularly important. As a criterion, the maximum luminous intensity lmax in cd of the luminaires is used (table 1.40). These values apply to
the distribution angle range from 60° to 90° to the vertical as well as all azimuth angles (angles in the horizontal plane, meaning all around) for horizontal escape routes, and
all distribution angles for luminaires in escape routes with other orientations such as staircases, ramps etc.