scope:

This specification covers the requirements for a Banner Signal using Fibre Optic Light guides.

The Signal is required to display a circular lit indication on which there is superimposed either a horizontal unlit (black) bar for the 'ON' aspect or a diagonal unlit (black) bar for the 'OFF' aspect.

The 'ON' aspect indication is to be achieved using a split light box fitted with two lamp units, each fed from an individual transformer, so as to ensure that both semi-circular lit areas of the 'ON' indication will be illuminated at approximately half the luminous intensity if one lamp unit fails.

The semi-circular lit areas of the 'OFF' aspect indication are to be illuminated together from a single designated lamp unit and individual transformer