700 – Emergency Systems

700.5(A) – Meter Mounted Transfer Switches

Change at a Glance:

A new last sentence is added to clarify that meter mounted transfer switches are not permitted for use in emergency systems.

700.5 Transfer Equipment. (Emergency Systems)

(A) General. Transfer equipment, including automatic transfer switches, shall be automatic, identified listed, and marked for emergency use, and approved by the authority having jurisdiction. Transfer equipment shall be designed and installed to prevent the inadvertent interconnection of normal and emergency sources of supply in any operation of the transfer equipment. Transfer equipment and electric power production systems installed to permit operation in parallel with the normal source shall meet the requirements of Article 705. Meter-mounted transfer switches shall not be permitted for emergency system use.

700.12(B) – Emergency System Equipment

Change at a Glance:

The reference to spaces with a 1-hour fire rating is revised to 2-hour, to correlate with the requirements of 700.10(D) and NFPA 110. Previous List item (3) addressing “health care occupancies where persons are not capable of self-preservation” was deleted to resolve conflicts between this section and NFPA 99.

700.12 General Requirements. (Sources of Power for Emergency Systems)

(B) Equipment Design and Location. 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(C) through (E)(H) shall be installed either in spaces fully protected by approved automatic fire suppression systems (sprinklers, carbon dioxide systems, and so forth) protection systems or in spaces with a 1-hour 2-hour fire rating where located within the following:
(1) Assembly occupancies for more than 1000 persons
(2) Buildings above 23 m (75 ft) in height with any of the following occupancy classes — assembly, educational, residential, detention and correctional, business, and mercantile
(3) Health care occupancies where persons are not capable of self-preservation
(4)(3) Educational occupancies with more than 300 occupants
Informational Note No. 1: For the definition of Occupancy Classification, see Section 6.1 of NFPA 101-2015 2018, Life Safety Code.
Informational Note No. 2: For further information, see ANSI/IEEE 493-2007, Recommended Practice for the Design of Reliable Industrial and Commercial Power Systems For information regarding power system reliability, see IEEE 3006.5-2014, Recommended Practice for the Use of Probability Methods for Conducting a Reliability Analysis of Industrial and Commercial Power Systems.

700.12(H) – DC Microgrid Systems

Change at a Glance:

New List Item (H) added to clarify that a dc microgrid system that is separate from the normal source of supply is permitted as an emergency system source.

700.12 General Requirements. (Sources of Power for Emergency Systems)

(H) DC Microgrid Systems. Sources connected to a dc microgrid system shall be permitted where the system is capable of being isolated from all non-emergency sources.
DC microgrid systems used as a source of power for emergency systems shall be of suitable rating and capacity to supply and maintain the total emergency load for not less than 2 hours of full-demand operation.
Where a dc microgrid system source serves as the normal supply for the building or group of buildings concerned, it shall not serve as the sole source of power for the emergency standby system.

700.32 Informational Note and Informational Note Figure 700.32 – Informational Note Figure 700.32

Change at a Glance:

A new informational note was added at 700.32 giving reference to a new Informational Note Figure 700.32, which gives an example of how emergency system overcurrent protective devices (OCPDs) selectively coordinate with all supply- side OCPDs.

700.32 Selective Coordination. (Emergency Systems)

Emergency system(s) overcurrent devices shall be selectively coordinated with all supply-side overcurrent protective devices. Selective coordination shall be selected by a licensed professional engineer or other qualified persons engaged primarily in the design, installation, or maintenance of electrical systems. The selection shall be documented and made available to those authorized to design, install, inspect, maintain, and operate the system.
Exception: Selective coordination shall not be required between two overcurrent devices located in series if no loads are connected in parallel with the downstream device.
Informational Note: See Informational Note Figure 700.32 for an example of how emergency system overcurrent protective devices (OCPDs) selectively coordinate with all supply-side OCPDs.

(See NEC text and illustration provided for complete informational note text)

Figure Informational Note Figure 700.32 Emergency System Selective Coordination.

(See NEC text and illustration provided for complete informational note figure text)

702.7(A) – Sign Indicating Optional Standby Power Source

Change at a Glance:

A sign is required to be placed at the residential emergency disconnecting means required by 230.85 that indicates the location of each permanently installed on-site optional standby power source disconnect.

702.7 Signs. (Optional Standby Systems)

(A) Standby. A sign shall be placed at the service- entrance equipment for commercial and industrial installations that indicates the type and location of each on-site optional standby power source. For one- and two-family dwelling units, a sign shall not be required for individual unit equipment for standby illumination placed at the disconnecting means required in 230.85 that indicates the location of each permanently installed on-site optional standby power source disconnect or means to shut down the prime mover as required in 445.18(D).