Table contains requirements for emergency lighting according to EN 1838. These values partially deviate from those in DIN VDE 0108. Its successor standard EN 50172 does not contain any concrete values for start delay (q.v. chapter 2.2.9 "Emergency lighting installations"). Emergency lighting planning is done using the corresponding isolux curves for the luminaire. They provide a luminaire’s horizontal illuminance at max. 0,2 m above the floor, apply for the specified mounting heights and, according to EN 1838, exclude light reflections on ceiling or walls. The maintenance factor of 0,80 is already incorporated. The overlay of isolux curves (addition of curve parameters) according to luminaire spacing facilitates simple testing as to whether the minimum illuminance of 1 lx is attained. Testing for the minimum illuminance of 0,5 lx on the central portion of the escape route over a width of 1 m can only be done using a point-by-point calculation of illuminance in most cases.

Figure 1.79: Isolux curve for an emergency light