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2005 NFPA 70, National Electric Code

The following excerpts are provided as a quick overview and may help as a guide in the selection, specification, and layout of emergency lighting products.

700-4 Tests and Maintenance.
(A) Conduct or Witness Test. The authority having jurisdiction shall conduct or witness a test on the complete system upon installation and periodically afterward.
(B) Tested Periodically. Systems shall be tested periodically on a schedule acceptable to the authority having jurisdiction to ensure the systems are maintained in proper operating condition.
(C) Battery Systems Maintenance. Where battery systems or unit equipments are involved, including batteries used for starting, control, or ignition in auxiliary engines, the authority having jurisdiction shall require periodic maintenance.
(D) Written Record. A written record shall be kept of such tests and maintenance.
(E) Testing Under Load. Means for testing all emergency lighting and power systems during maximum anticipated load conditions shall be provided.
FPN: For testing and maintenance procedures of emergency power systems (EPSSs), see NFPA 110-2002, Standard for Emergency and Standby Power Systems.

700.8 Signs.
(A) Emergency Sources. A sign shall be placed at the service entrance equipment, indicating type and location of on-site emergency power sources.
Exception: A sign shall not be required for individual unit equipment as specified in 700.12(F).
(B) Grounding. Where the grounded circuit conductor connected to the emergency source is connected to a grounding electrode conductor at a location remote from the emergency source, there shall be a sign at the grounding location that shall identify all emergency and normal sources connected at that location.

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 (4): (1) Wiring from the normal power source located in transfer equipment enclosures. (2) Wiring supplied from two sources in exit or emergency luminaires (lighting fixtures). (3) Wiring from two sources in a common junction box, attached to exit or emergency luminaires (lighting fixtures). (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 equipment.

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 700.12(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 700.12(E) where located within assembly occupancies for greater than 1000 persons or in buildings above 75 ft (23 m) in height with any of the following 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 101-2003, 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 1½ hours, without the voltage applied to the load falling below 87½ percent of normal.
For a sealed battery, the container shall not be required to be transparent. However, for the lead acid battery that requires water additions, transparent or translucent jars shall be furnished. Automotive-type batteries shall not be used.
An automatic battery charging means shall be provided.
(F) Unit Equipment. Individual unit equipment for emergency illumination shall consist of the following: (1) A rechargeable battery. (2) A battery charging means. (3) Provisions for one or more lamps mounted on the equipment, or shall be permitted to have terminals for remote lamps, or both. (4) A relaying device arranged to energize the lamps automatically upon failure of the supply to the unit equipment.
The batteries shall be of suitable rating and capacity to supply and maintain at not less than 87½ percent of the nominal battery voltage for the lamp load associated with the unit for a period of at least 1½ hours, or the unit equipment shall supply and maintain not less than 60 percent of the initial emergency illumination for a period of at least 1½ hours. Storage batteries, whether of the acid or alkali types, shall be designed and constructed to meet the requirements of emergency service.
Unit equipment shall be permanently fixed in place (i.e., not portable) and shall have all wiring to each unit installed in accordance with the requirements of any of the wiring methods in Chapter 3. Flexible cord-and-plug connection shall be permitted, provided that the cord does not exceed 3 feet (900mm) in length. The branch circuit feeding the unit equipment shall be the same branch circuit as that serving the normal lighting in the area and connected ahead of any local switches. The branch circuit that feeds unit equipment shall be clearly identified at the distribution panel. Emergency luminaires (illumination fixtures) that obtain power from a unit equipment and are not part of the unit equipment shall be wired to the unit equipment as required by 700.9 and by one of the wiring methods of Chapter 3.
Exception: In a separate and uninterrupted area supplied by a minimum of three normal lighting circuits, a separate branch circuit for unit equipment shall be permitted if it originates from the same panelboard as that of the normal lighting circuits and is provided with a lock-on feature.

IV. Emergency System Circuits for Lighting & Power
700-15 Loads on Emergency Branch Circuits. No appliances and no lamps, other than those specified as required for emergency use, shall be supplied by emergency lighting circuits.
700-16 Emergency Illumination. Emergency illumination shall include all required means of egress lighting, illuminated exit signs, and all other lights specified as necessary to provide require illumination.
Emergency lighting systems shall be designed and installed so that the failure of any individual lighting element, such as the burning out of a light bulb, cannot leave in total darkness any space that requires emergency illumination.
Where high-intensity discharge lighting such as high- and low-pressure sodium, mercury vapor, and metal halide is used as the sole source of normal illumination, the emergency lighting system shall be required to operate until normal illumination has been restored.
Exception: Alternative means that ensure emergency lighting illumination level is maintained shall be permitted.