08.03.13 - Emergency Exit Sign Viewing Distances & Considerations (Emergency Lighting)

When installing Emergency Signage there are a few things that you need to consider and calculations you have to make. When a Fire officer or SRC Fire Engineer is surveying your premises he/she is making sure that occupants of every room can clearly determine the exit route should an emergency situation occur. To make this calculation they will walk around the area or routes and decide where the emergency exit is and the maximum distance somebody could be from it.

This will establish the maximum viewing distance.

The maximum viewing distance deemed safe to be viewed from is given in BS 5266 Pt7  and you will need to work to these guidelines. We will be featuring the SRC Fire version of the guidelines in the coming months. This will be an easy to read and understand visual guide so stay tuned for that.

In short, below are the guidelines for:

Internally Illuminated Exit Sign

The maximum viewing distance is 200 x the panel height.

Therefore if the sign is 175mm high then the maximum viewing distance is 35000mm or 35 meters.
175mm x 200 = 35000 mm (35 meters)

or

12 inches x 200 = 2400 inches (200 feet)

Externally Illuminated Exit Sign

The maximum viewing distance is 100 x the panel height.

Therefore if the sign is 175mm high then the maximum viewing distance is 17500mm or 17.5 meters.

175mm x 100 = 17500 mm (17.5 meters)

or

12 inches x 100 = 1200 inches (100 feet)

Summary

Greater viewing distances are achieved through internally illuminated exit signs. Externally illuminated signs are easy to install but they still need an emergency light to illuminate it during loss of power. If you have limited space above an emergency exit door and can only use a smaller sign, but the room is bigger than the viewing distance, then you will need more than one sign to indicate the direction of travel.

The above information is an overview guide. We recommend that you always seek advice from qualified emergency signage/lighting installer to ensure that you comply with the local and national laws.