EMERGENCY LIGHTING DESIGN GUIDE – LEGEND VIEWING DISTANCES
![Zemper Exit Sign](https://zemper.com/coatzem/uploads/2023/04/zemper-exit-sign-hall.jpg)
LEGEND VIEWING DISTANCES
BS5266 and BS5499 define the viewing distances for exit signs, these are spilt into two categories;
a. INTERNALLY illuminated exit signs
b. EXTERNALLY illuminated exit signs
The calculation is as follows:
Viewing Distance (D) = The overall height of legend (H) x Factor (F)
![](https://www.philippayne.co.uk/wp-content/uploads/2021/07/Viewing-Distance.png)
NOTE
- You must remember the legend has a 5mm transparent border.
- The sign height is the printed area/safety colour green only, the below image helps explain this.
![](https://www.philippayne.co.uk/wp-content/uploads/2021/07/Sign-Height.png)
Things to consider:
- Escape route signs should be cleaned and visually inspected at regular intervals
a. INTERNALLY illuminated exit signs
Examples of internally illuminated exit signs:
![harena-led-tum-per](https://zemper.com/coatzem/uploads/2016/10/harena-led-tum-per.jpg)
![Kons](https://zemper.com/coatzem/uploads/2017/02/kons-tum-per.jpg)
![ExitAlya-negra-recessed](https://zemper.com/coatzem/uploads/2020/03/ExitAlya-negra-recessed.jpg)
Internally illuminated signs have a multiplying factor (F) of 200.
![](https://www.philippayne.co.uk/wp-content/uploads/2021/07/Exit-200.png)
Example: Legend green height is 135mm
Viewing Distance
= The overall height of legend (H) x Factor (F)
= 135mm x 200
= 27,000mm
= 27M
Examples of externally illuminated exit signs:
![](https://www.philippayne.co.uk/wp-content/uploads/2021/07/legend-viewing-distances-1.jpg)
![](https://www.philippayne.co.uk/wp-content/uploads/2021/07/legend-viewing-distances-2.jpg)
![](https://www.philippayne.co.uk/wp-content/uploads/2021/07/legend-viewing-distances-3.jpg)
Externally illuminated signs have a multiplying factor (F) of 100.
![](https://www.philippayne.co.uk/wp-content/uploads/2021/07/Exit-100.png)
Example: Legend green height is 135mm
Viewing Distance
= The overall height of legend (H) x Factor (F)
= 135mm x 100
= 13,500mm
= 13.5M