23.1 A single hazardous event shall not be capable
of disabling all lighting systems.
23.2 Lighting circuits shall be distributed through
the spaces so that a total blackout cannot occur due to the failure
of a single protective device.
23.3 Where general lighting is provided by a single
centralised source, an alternative source of lighting shall also be
provided sufficient to enable persons to make their way to the open
deck or to permit work on essential machinery.