spaschal on DSK3GDR082PROD with CFR

Federal Aviation Administration, DOT

Section 25.812

Section 25.812 Emergency lighting.
(a) An emergency lighting system,
independent of the main lighting system, must be installed. However, the
sources of general cabin illumination
may be common to both the emergency
and the main lighting systems if the
power supply to the emergency lighting system is independent of the power
supply to the main lighting system.
The emergency lighting system must
include:
(1) Illuminated emergency exit marking and locating signs, sources of general cabin illumination, interior lighting in emergency exit areas, and floor
proximity escape path marking.
(2) Exterior emergency lighting.
(b) Emergency exit signs - 
(1) For airplanes that have a passenger seating configuration, excluding
pilot seats, of 10 seats or more must
meet the following requirements:
(i) Each passenger emergency exit locator sign required by Section 25.811(d)(1) and
each passenger emergency exit marking sign required by Section 25.811(d)(2) must
have red letters at least 11-2 inches high
on an illuminated white background,
and must have an area of at least 21
square inches excluding the letters.
The lighted background-to-letter contrast must be at least 10:1. The letter
height to stroke-width ratio may not
be more than 7:1 nor less than 6:1.
These signs must be internally electrically illuminated with a background
brightness of at least 25 foot-lamberts
and a high-to-low background contrast
no greater than 3:1.
(ii) Each passenger emergency exit
sign required by Section 25.811(d)(3) must have
red letters at least 11-2 inches high on a
white background having an area of at
least 21 square inches excluding the
letters. These signs must be internally
electrically illuminated or self-illuminated by other than electrical means
and must have an initial brightness of
at least 400 microlamberts. The colors
may be reversed in the case of a sign
that is self-illuminated by other than
electrical means.
(2) For airplanes that have a passenger seating configuration, excluding
pilot seats, of nine seats or less, that
are required by Section 25.811(d)(1), (2), and (3)
must have red letters at least 1 inch
high on a white background at least 2

inches high. These signs may be internally electrically illuminated, or selfilluminated by other than electrical
means, with an initial brightness of at
least 160 microlamberts. The colors
may be reversed in the case of a sign
that is self-illuminated by other than
electrical means.
(c) General illumination in the passenger cabin must be provided so that
when measured along the centerline of
main passenger aisle(s), and cross
aisle(s) between main aisles, at seat
arm-rest height and at 40-inch intervals, the average illumination is not
less than 0.05 foot-candle and the illumination at each 40-inch interval is not
less than 0.01 foot-candle. A main passenger aisle(s) is considered to extend
along the fuselage from the most forward passenger emergency exit or
cabin occupant seat, whichever is farther forward, to the most rearward passenger emergency exit or cabin occupant seat, whichever is farther aft.
(d) The floor of the passageway leading to each floor-level passenger emergency exit, between the main aisles
and the exit openings, must be provided with illumination that is not less
than 0.02 foot-candle measured along a
line that is within 6 inches of and parallel to the floor and is centered on the
passenger evacuation path.
(e) Floor proximity emergency escape path marking must provide emergency evacuation guidance for passengers when all sources of illumination more than 4 feet above the cabin
aisle floor are totally obscured. In the
dark of the night, the floor proximity
emergency escape path marking must
enable each passenger to - 
(1) After leaving the passenger seat,
visually identify the emergency escape
path along the cabin aisle floor to the
first exits or pair of exits forward and
aft of the seat; and
(2) Readily identify each exit from
the emergency escape path by reference only to markings and visual features not more than 4 feet above the
cabin floor.
(f) Except for subsystems provided in
accordance with paragraph (h) of this
section that serve no more than one assist means, are independent of the airplane-s main emergency lighting system, and are automatically activated

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