700.9 Wiring, Emergency System.
(B) Wiring. Wiring of two or more emergency circuits
supplied from the same source shall be permitted in the
same raceway, cable, box, or cabinet. Wiring from an emergency
source or emergency source distribution overcurrent
protection to emergency loads shall be kept entirely independent
of all other wiring and equipment, unless otherwise
permitted in (1) through (5):
(1) Wiring from the normal power source located in transfer
equipment enclosures
(2) Wiring supplied from two sources in exit or emergency
luminaires
(3) Wiring from two sources in a common junction box,
attached to exit or emergency luminaires
(4) Wiring within a common junction box attached to unit
equipment, containing only the branch circuit supplying
the unit equipment and the emergency circuit supplied
by the unit equipment
(5) Wiring from an emergency source to supply any combination
of emergency, legally required, or optional
loads in accordance with (a), (b), and (c):
a. From separate vertical switchboard sections, with or
without a common bus, or from individual disconnects
mounted in separate enclosures.
b. The common bus or separate sections of the switchboard
or the individual enclosures shall be permitted
to be supplied by single or multiple feeders without
overcurrent protection at the source.
Exception to (5)(b): Overcurrent protection shall be permitted
at the source or for the equipment, provided the overcurrent
protection is selectively coordinated with the downstream
overcurrent protection.
c. Legally required and optional standby circuits shall
not originate from the same vertical switchboard
section, panelboard enclosure, or individual disconnect
enclosure as emergency circuits.
