Article 700 Emergency Systems

A. General



This article lays out the electrical safety requirements for the installation, operation, and maintenance of emergency systems. Emergency systems include all items necessary to deliver electricity to the load. Emergency systems are defined as those which are legally required by any governmental agency or specific code that has jurisdiction. They supply, distribute, and control electricity for power and illumination which is essential for safety to human life. The code goes into detail with specific types of occupancies and equipment. The reader is referred to other articles in this code or to other NFPA documents for additional information as follows:

NEC Article 517 Health Care Facilities for wiring and installation in health care facilities

NFPA 99-2002 Standard for Health Care Facilities for performance and maintenance in health care facilities

NFPA 101-2003 Life Safety Code for locations where the systems are essential to life safety

NFPA 110-2002 Emergency and Standby Power Systems for performance of these systems

These additional documents and articles may place other restrictions on the design of the emergency system for the specific application of the document or article.


Application of Other Articles

All applicable articles of the NEC® apply unless they are modified by this Article.


Equipment Approval

All equipment must be approved for this use.


Tests and Maintenance

(A) Conduct or Witness Test. The system must be tested at installation and periodically thereafter. The test must be conducted and witnessed by the authority having jurisdiction.

(B) Tested Periodically. To assure proper maintenance and operation the system must be tested on a schedule accepted by the authority having jurisdiction.

(C) Battery System Maintenance. Batteries, whether for systems or in conjunction with engines, must be maintained periodically.

(D) Written Record. A written record must be kept of all tests and maintenance.

(E) Testing under Load. Provisions must be made to test the system under the maximum anticipated load.



(A) Capacity and Rating. The system must be able to supply the entire load operating together. It must also be able to withstand the maximum available fault current.

(B) Selective Load Pickup, Load Shedding, and Peak Load Shaving. This permits the system to be used for various levels of loads and peak shaving provided that it can supply the emergency circuits, the legally required standby circuits, and the optional standby circuits when required.


Transfer Equipment

The transfer equipment must be automatic. Interconnection of the normal and emergency sources must be prevented. Bypass means for isolation of the transfer switch are permitted. Automatic transfer switches must be electrically operated and mechanically held. Transfer equipment can supply only emergency loads.



Audible and visual signal must be installed where practical to indicate the derangement of the emergency source, that the battery is carrying the load, the battery charger is not functioning, and there is a ground fault in solidly grounded wye systems of more than 150 V to ground and circuit protective devices rated more than 1000 A. There is additional information concerning the ground-fault devices.




II. Circuit Wiring


Wiring, Emergency Systems

(A) Identification. All items in the system must be readily identified as part of the system.

(B) Wiring. The wiring of the system must be separate from the wiring of the normal system and cannot be in the same raceway, boxes, cabinets, cables, etc. There are four exceptions.

(C) Wiring Design and Location. The circuits must be designed and located to reduce to a minimum the hazards due to flooding, vandalism, icing, fires, and other adverse conditions.

(D) Fire Protection. Additional requirements are noted.

III. Sources of Power


General Requirements

The current must be available for use within 10 seconds after the loss of normal power. The supply source can be any of the following: storage batteries, generator set, separate service, uninterruptible power supply, fuel cell system, and unit equipment. Each one is covered in the code in detail as to specific requirements. Again it must be noted that some of these may not be permitted for specific occupancies as noted in other documents (i.e., health care facilities). The equipment must be designed and located so that hazards from flooding, vandalism, icing, and fires are minimized. There are requirements for buildings with certain sizes and equipment. There are also additional requirements for storage batteries, generator set, uninterruptible power supplies, fuel cell system, separate service, and unit equipment.

IV. Emergency System Circuits for Lighting and Power


Loads on Emergency Branch Circuits

Only those appliances and lamps needed for emergency use can be connected to the emergency lighting circuits.


Emergency Illumination


Circuits for Emergency Lighting


Circuits for Emergency Power


V. ControlEmergency Lighting Circuits


Switch Requirements


Switch Location


Exterior Lights


VI. Overcurrent Protection




Ground-Fault Protection of Equipment

This is not required for the alternate source. Ground fault indication is required in accordance with Section 700.7(D).



Article 90 Introduction


Wiring and Protection

Wiring Methods and Materials

Equipment for General Use

Special Occupancies

Special Equipment

Special Conditions


Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size

Annex D. Examples

Annex E. Types of Construction

Pocket Guide to the National Electrical Code 2005
Pocket Guide to the National Electrical Code(R), 2005 Edition (8th Edition)
ISBN: 0131480014
EAN: 2147483647
Year: 2004
Pages: 120 © 2008-2020.
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