Safety signs located at exits and along escape routes should be adequately illuminated. The aim of escape route lighting is toclearly indicate the evacuation route to the designated assembly point. At least one illuminated safety sign must be visible from any point on the escape route.
There is a distinction between safety signs that are illuminated from the inside and from the outside. The maximum viewing distance of the safety sign is the largest distance from which it is still legible and recognisable. It depends on the installation height of the pictogram and the type of illumination used for the safety sign indicating the escape route direction, however the visibility is twice as high in signs that are illuminated from the inside, i.e. safety sign luminaires.
Escape route safety signs:
- Safety signs include escape route direction signs, emergency exit signs and other safety signs deemed by risk assessment as needing to be legible under emergency lighting conditions
- Safety signs must comply with ISO 3864-1, ISO 3864-4 (photometry) and EN ISO 7010 (design)
Safety sign luminance:
- A luminance of at least 2 cd/m2 is required on the entire area of the safety colour of the sign.
- The maximum to minimum luminance ratio within either the white or the safety colour portion of the sign may not exceed 10:1. High variations between adjacent points should also be avoided.
- The luminance contrast colour to safety colour ratio may not be lower than 5:1 nor greater than 15:1.
- Safety sign luminaires must have a minimum backup duration of 1 hour.
Viewing distance
The maximum viewing distance of the safety sign is the largest distance from which it is still legible and recognisable.The viewing distance is calculated as l = z x h, where l is the distance of observation, h is the height of the sign and z is the distance factor (z is a constant with a value of 100 for externally illuminated signs and 200 for internally illuminated signs).
When we are placing exit sign luminaires during the lighting design process, the distance between the luminaires should never exceed the viewing distance of the luminaires we are using for this purpose.
A frequently asked question is ”At what height should emergency safety signs be mounted?”
Safety signs should be mounted no higher than 20 above the horizontal view according to the definition of the maximum viewing distance of the sign.
The first limitation is that these luminaires may not be mounted any lower than at two metres. The second limitation is that they may not be mounted any higher than at twenty degrees above the horizontal view. This translates to one point that’s located seven metres above the floor. And in accordance with the maximum viewing distance of the sign, we end up with a height that’s seven to eleven metres above floor level.
Designing safety signs
The ISO 7010 standard establishes safety signs for the purpose of preventing accidents, ensuring fire safety, informing about health hazards and facilitating emergency evacuation .
| Category | Meaning | Colour | Shape | Example |
| E | the category for signs indicating an evacuation route, the location of safety equipment or a safety facility, or a safety action | green | square or rectangular |  |
| F | the category for fire equipment signs | red | square or rectangular |  |
| M | the category fot mandatory action signs | blue | circle |  |
| P | the category for prohibition signs | red | circle |  |
| W | the category for warning signs | yellow | triangle |  |