Yes you are correct, unfortunately some of the previous posts have not been accurate. The requirements for safety signs and emergency lighting is covered in a number of standards and there are various guides to their installation. A good starting point would be referencing BS 5266, ICEL 1006 and EN 1838. The key requirements are :- - emergency exit signs must be illuminated, either by an internal source or an external source that will not fail in the event of a power failure - viewing distance is 200 x h of sign for internally illuminated and 100 x h of sign for externally illuminated signs. If the viewing distance is greater then intermediate signs need to be placed along the escape route, which also must be illuminated with regard to the emergency lighting, the key points are :- - 1 lux along the centre line of the escape route - illumination level achieved along the route by 2 units in the event of a failure of 1 - illuminate each tread of a flight of stairs - illuminate changes of level - illuminate each change of direction - illuminate fire fighting equipment and call points The use of photoluminescent signs is good practice, but does not meet the requirement for illumination as there is no guarantee that they have been exposed to sufficient light in order to glow in an emergency situation.