7.2.4. MINIMUM LETTER HEIGHT
Where comprehensibility of the graphic symbol cannot be assured, and reliance
on supplementary text is needed in darkness, the minimum letter height
of signs containing supplementary text should take into account the viewing
distance in darkness, as well as the legibility distances as described
in the table below, providing a choice between letter height and luminance
of material as follows:-
| Minimum Upper | Maximum Viewing Distance in Metres | ||
| and Lower Case | Under Normal | During Power Loss | |
| Letter Height | Lighting | Class 11 | Class I |
| 20mm | 7.5m to 10m | 1m to 2m | 2m to 4m |
| 50mm | 20m | 3.0m | 6.0m |
| 75mm | 30m | 4.5m | 9.0m |
| 100mm | 40m | 6.0m | 12m |
| 125mm | 50m | 7.5m | 15m |
| 300mm | > 50m | 18m | 36m |
| "X" | V = 0.4 | V = 0.06 | V=0.12 |
| "X" letter height in mm X V ? viewing distance in metres. | |||
7.3. WIDTH OF CONTINUOUS ESCAPE PATH WALL
AND FLOOR LINE MARKERS
In Section 9. of this Code of Practice, continuous,
unbroken, low location lighting line marking of escape paths
at floor or skirting board level supplemented, in higher risk areas, with
other continuous line markings on walls at various levels, is recommended.
Where the use of alternative classes of material are permitted in this
Code of Practice, the line width may be varied according to the luminance
of the materials as follows:-
| Luminance Class II | Luminance Class I | |
|
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|
Line width |
N/A | 30mm |
| 50mm | 35mm | |
| 80mm | 60mm | |
| 100mm | 75mm | |
| 200mm | 150mm | |
|
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7.4. USE OF CLASS III LUMINANCE MATERIALS
AND PRODUCTS
Photoluminescent products with luminance properties in Class I I I should
only be installed as a complement to systems installed principally
with Class I and Class II materials as, for example, highlight for the
edges of obstacles, stair and architectural trim edges and floor coverings.
Obstacles
Architectural trim
Floor/matting lines
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