Here is a quote from the FCOM re emergency exit lights.....DESCRIPTION
EXIT signs come on if cabin altitude gets too high or (depending on the CIDS/CAM programming), if NO SMOKING signs come on.
The proximity emergency escape path marking system, overhead emergency lighting and EXIT signs come on if the EMER EXIT LT selector is ON or if the EMER pushbutton on the purser panel is pressed.
With the EMER EXIT LT selector at ARM :
The proximity emergency escape path marking system comes on if :
Normal aircraft electrical power fails or,
DC SHED ESS BUS is lost.
The overhead emergency lights come on if :
Normal aircraft electrical power system fails or
DC SHED ESS BUS fails or
AC BUS 1 fails
Exit signs automatically come on if :
Normal aircraft electrical power system fails or
DC SHED ESS BUS fails
When lighted :
The proximity emergency escape path marking system is powered by internal batteries of 12 minutes duration.
DC SHED ESS BUS supply the overhead emergency lights and the EXIT signs.
If DC SHED ESS BUS fails, batteries inside the light fixtures power all the lights.
DC SHED ESS BUS charge the internal batteries if :
EMER LT selector is not at ON and
the EMER pushbutton on purser panel is not pressed and
DC SHED ESS BUS is supplied.
I think that about covers the emergency lights....
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Dont forget you wont be leaving empty handed!
[This message has been edited by Boxer (edited 13 October 2000).]