Page 176 - Offshore Electrical Engineering Manual

Emergency Escape Lighting 163

The apparent intensity of each light assembly after all losses should not be less
than 14,000 cd. The total beam width in the vertical plane should not be less than
2.5°degrees at the point on the curve of intensity distribution where the intensity is
10% of maximum.
The lamp assembly is normally equipped with a two-filament lamp in a rotating
lamp changer unit (charged with up to 6 lamps) which automatically ensures that a
functioning filament is in circuit and in the correct focal position. The failure of the
light assembly for any reason should cause an alarm to be initiated and the secondary
battery operated lights be switched on.
The secondary and main lamps are normally positioned one above the other,
with the secondary positioned below. The secondary lamp assemblies are of similar
design to the main lamp assemblies, but the lamps are less powerful, having a range
of 10 nautical miles.
Subsidiary, red flashing lights are required at the corners not marked by the main
and secondary lights. These have the same characteristics as the secondary lights and
are also battery-backed, but have a nominal range of 3 nautical miles.

WALKWAYS, CATWALKS AND STAIRWAYS
Installation personnel need to be able to make their way to most parts of the platform,
at any time of the day or night, and in any weather. Therefore good lighting of all
accessways and particularly stairways is vital for their safety. Most if not all installa-
tion lighting outside the accommodation areas will remain on continuously day and
night.

EMERGENCY ESCAPE LIGHTING
Throughout the installation at least one in every four luminaires should be of the
integral battery emergency type. These luminaires remain lit at all times, and will
provide illumination for at least 1 h following a power failure. These lamps should
be placed at strategic locations on escape routes such as inside process modules at
ladders and exit doors to ensure adequate escape lighting is available in emergencies.
They should also illuminate the controls to fixed firefighting equipment. This may
require the one-in-every-four ratio to be increased, and in congested areas all lumi-
naires may require to be of the integral battery type.
Certain requirements are laid down in PFEER Guidance Notes and are there-
fore mandatory on offshore installations. Notably, these requirements include the
following:

1. The minimum duration of escape lighting after failure of normal lighting is now
based on the Installation Safety Case, but is normally at least 1 h.
2. Adequate lighting of Firefighting Equipment Controls during emergencies.