mm (2 in.) of concrete
(6) Be a cable listed to maintain circuit integrity for not less than 1 hour when installed in accordance with the listing requirements
(2) Feeder-Circuit Equipment. Equipment for feeder cir cuits (including transfer switches, transformers, and panel-boards) shall be located either in spaces fully protected by approved automatic fire suppression systems (including sprinklers, carbon dioxide systems) or in spaces with a 1-hour fire resistance rating.
FPN: For the definition of Occupancy Classification, see
Section 6.1 of NFPA 707-2006, Life Safety Code.
(3) Generator Control Wiring. Control conductors in stalled between the transfer equipment and the emergency generator shall be kept entirely independent of all other wiring and shall meet the conditions of 700.9(D)(1).
III. Sources of Power
700.12 General Requirements. Current supply shall be such that, in the event of failure of the normal supply to, or within, the building or group of buildings concerned, emergency lighting, emergency power, or both shall be available within the time required for the application but not to exceed 10 seconds. The supply system for
emergency purposes, in addition to the normal services to the building and meeting the general requirements of this section, shall be one or more of the types of systems described in 700.12(A) through (E). Unit equipment in accordance with 700.12(F) shall satisfy the applicable requirements of this article.
In selecting an emergency source of power, consideration shall be given to the occupancy and the type of service to be rendered, whether of minimum duration, as for evacuation of a theater, or longer duration, as for supplying emergency power and lighting due to an indefinite period of current failure from trouble either inside or outside the building.
Equipment shall be designed and located so as to minimize the hazards that might cause complete failure due to flooding, fires, icing, and vandalism.
Equipment for sources of power as described in
700.12(A) through (E) where located within assembly
occupancies for greater than 1000 persons or in
buildings above 23 m (75 ft) in height with any of the
following occupancy classes — assembly, educational,
residential, detention and correctional, business, and
mercantile — shall be installed either in spaces fully
protected by approved automatic fire suppression
systems (sprinklers, carbon dioxide systems, and so
forth) or in spaces with a 1 -hour fire rating.
FPN No. 1: For the definition of Occupancy Classification, see Section 6.1 of NFPA 707-2006, Life Safety Code.
FPN No. 2: Assignment of degree of reliability of the recognized emergency supply system depends on the careful evaluation of the variables at each particular installation.
(A) Storage Battery. Storage batteries used as a source of power for emergency systems shall be of suitable rating and capacity to supply and maintain the total load for a minimum period of 1 Vi hours, without the voltage applied to the load falling below 8V/2 percent of normal.
Batteries, whether of the acid or alkali type, shall be designed and constructed to meet the requirements of emergency service and shall be compatible with the charger for that particular installation.
For a sealed