The viewing distance of an exit sign is calculated as d = z × h: pictogram height multiplied by a distance factor, with z = 100 for externally illuminated and z = 200 for internally illuminated signs. An internally illuminated sign with a 15 cm pictogram can therefore be recognised from up to 30 m, an externally illuminated sign of the same size only from 15 m. ISO 7010 exit signs belong at every exit and every change of direction, so that a sign is visible from every point on the escape route.
What are ISO 7010 safety signs?
Exit signs are green and white safe condition signs that mark escape routes, emergency exits and emergency equipment. Their design and meaning are standardised internationally in ISO 7010, adopted in Europe as EN ISO 7010. National rules govern how they are applied – in Germany, for instance, workplace rule ASR A1.3. The most important safe condition signs:
| Code | Meaning | Use |
|---|---|---|
| E001 | Emergency exit (left hand) | exit or route to the left |
| E002 | Emergency exit (right hand) | exit or route to the right |
| E003 | First aid | first aid equipment |
| E004 | Emergency telephone | emergency call points |
| E007 | Evacuation assembly point | assembly point outdoors |
| E010 | Automated external defibrillator (AED) | location of a defibrillator |
E001 and E002 are usually combined with a supplementary direction arrow. Fire equipment signs such as F001 (fire extinguisher) are red and white and form a separate category, but must also be visible in emergency mode – see Emergency lighting illuminance.
Internally or externally illuminated: what is the difference?
Exit signs must remain legible during a power failure. There are two solutions:
- Internally illuminated sign: the pictogram is part of an exit sign luminaire and lit from within. It is high-contrast, even and, for the same size, legible from twice the distance.
- Externally illuminated sign: a printed sign is lit by a nearby emergency luminaire. Legibility depends heavily on how luminaire and sign are positioned relative to each other.
There are also photoluminescent signs that store light. As a rule they supplement electrical escape lighting – for example in low-level wayfinding systems – rather than replace it.
How is viewing distance calculated?
EN 1838 sets out a simple formula:
d = z × h
- d is the maximum viewing distance in metres.
- h is the height of the pictogram in metres.
- z is the distance factor: 100 for externally illuminated and 200 for internally illuminated signs.
An internally illuminated sign is therefore legible from twice the distance for the same size. Conversely, the required pictogram height follows from the required distance: h = d ÷ z.
Worked examples
| Pictogram height h | Externally illuminated (z = 100) | Internally illuminated (z = 200) |
|---|---|---|
| 5 cm | 5 m | 10 m |
| 10 cm | 10 m | 20 m |
| 15 cm | 15 m | 30 m |
| 20 cm | 20 m | 40 m |
| 25 cm | 25 m | 50 m |
Example: a corridor is 26 m long and the next sign hangs at the far end. An externally illuminated sign would need a pictogram at least 26 cm high, an internally illuminated one only 13 cm. The NOTLUX exit sign luminaire is designed for a viewing distance of 30 m and uses a replaceable pictogram film, so the direction or symbol can be changed after alterations without replacing the luminaire.
Practical tip: Calculate with the height of the pictogram, not the height of the luminaire housing. Manufacturer viewing distance claims should refer to EN 1838.
What luminance and contrast are required?
EN 1838 sets photometric minimums for illuminated safety signs:
| Criterion | Requirement |
|---|---|
| Luminance of the safety colour (green) | at least 2 cd/m² in all relevant viewing directions |
| Uniformity within a colour | ratio of maximum to minimum luminance no more than 10 : 1 |
| Contrast white to green | luminance ratio between 5 : 1 and 15 : 1 |
| Response | 50 % of luminance within 5 s, 100 % within 60 s |
Unevenly lit or yellowed signs often no longer meet these values, even if they still appear to "work". Internally illuminated signs achieve uniformity far more easily by design than externally illuminated ones.
Where must exit signs be placed?
The basic principle: from every point on an escape route, at least one sign leading to the nearest exit must be visible. Typical positions follow from that:
- above or directly next to every emergency exit and every exit door on the escape route,
- at every change of direction and every corridor intersection,
- at stairs where the direction of travel is not obvious,
- along long corridors at intervals that do not exceed the viewing distance,
- at points from which the exit cannot be seen directly.
On mounting height: signs should sit within the natural field of view while remaining clearly visible above people, shelving and open door leaves. In practice they are usually mounted above doors or suspended from the ceiling. In a fire, smoke collects under the ceiling first, so in buildings with a heightened smoke risk a lower mounting position or a low-level wayfinding system may make sense. The fire safety strategy and national rules are decisive.
Common mistakes with exit signs
- Signs too small for the actual distance, often because externally illuminated signs were sized like internally illuminated ones.
- Obstructed signs behind decorations, banners, shelving, acoustic panels or open door leaves.
- Wrong arrow direction after alterations or a changed room layout.
- Mixed pictogram generations in the same building, which can confuse occupants.
- Externally illuminated signs without enough light, because the associated emergency luminaire was moved or removed.
- No testing: exit sign luminaires are part of the monthly functional test – see Testing intervals.
Outdated pictograms: must they be replaced?
Before ISO 7010, Europe used several different exit sign designs. In Germany, signs to DIN 4844 and BGV A8 were common, with a differently drawn "running man" and different door and arrow layouts; other countries had their own variants, including signs based on the earlier European signage directive. ISO 7010 is now the standard for new installations across Europe.
Existing signs do not always have to be replaced immediately. They should, however, be converted to ISO 7010 at the latest during refurbishment, extension or luminaire replacement, and mixing old and new signs in the same building should be avoided. Whether replacement is required depends on the risk assessment, the fire safety strategy and any findings from an authority inspection.
Frequently asked questions
How large must an exit sign be?
Size follows from the viewing distance: pictogram height h equals distance d divided by factor z. For 20 m, an internally illuminated sign needs a 10 cm pictogram, an externally illuminated one 20 cm.
What do z = 100 and z = 200 mean?
They are the distance factors defined in EN 1838. z = 100 applies to externally illuminated signs, z = 200 to internally illuminated signs, which are therefore legible from twice the distance for the same size.
What luminance must an exit sign have?
Under EN 1838, the green safety colour must reach at least 2 cd/m² in all relevant viewing directions. The ratio of maximum to minimum luminance within a colour must not exceed 10 : 1.
Are the old "running man" signs still permitted?
Existing signs to older national designs may often remain for the time being, but new installations use ISO 7010 signs. During alterations they should be converted, and mixing designs should be avoided.
How many exit signs does a room need?
Enough that at least one sign leading to the nearest exit is visible from every point on the escape route. Spacing must not exceed the viewing distance of the signs, and a sign is needed at every change of direction.
Emergency lighting without worries.
Luminaires, installation and maintenance from a single source – every inspection documented digitally in our app. We start with a free on-site survey and standard-compliant design.