1 Scope

1.1 These requirements cover automatic, non-automatic, and manual transfer switches, operating at voltages of greater than 1000 Vac, and intended for use in non-hazardous locations in accordance with Annex B, Item 1, the National Electrical Code, ANSI/NFPA 70, or the Canadian Electrical Code, CSA C22.1, Part 1, to provide for power as follows:

1. a) Automatic transfer switches for use in emergency systems in:

   1. 1) Emergency systems in accordance with the Standard for Emergency Electrical Power Supply for Buildings, CSA C282-15;

   2. 2) Health care facilities in accordance with Rule 24-304 of the Canadian Electrical Code (CEC) Part I;

   3. 3) Articles 517, Health Care Facilities, and 700, Emergency Systems, of the National Electrical Code, ANSI/NFPA 70 (refer to Annex B, Item 1); and

   4. 4) The Health Care Facilities Code, ANSI/NFPA 99, (refer to Annex B, Item 12).

2. Note: Transfer switches for optional standby systems are not recognized in Canada.

3. b) Transfer switches for use in optional standby systems in accordance with Article 702 of the National Electrical Code, ANSI/NFPA 70 (refer to Annex B, Item 1).

4. Note: Automatic transfer switches for optional standby systems are not recognized in Canada.

5. c) In legally required standby systems in accordance with Article 701 of the National Electrical Code, ANSI/NFPA 70(refer to Annex B, Item 1).

6. Note: Legally-required standby systems are not recognized in Canada.

7. d) Automatic transfer switches for use in accordance with the Standard for the Installation of Stationary Pumps for Fire Protection, ANSI/NFPA 20 or the Standard for Fire Pump Controllers, CSA C22.2 No. 263, (refer to Annex B, Item 2).

1.2 These requirements cover transfer switches rated greater than 1000 V to 46 kV.

1.3 These requirements cover transfer switches together with their associated control devices including, but not limited to, voltage sensing relays, frequency sensing relays, and time delay relays.

1.4 An automatic transfer switch as covered by these requirements is a device that automatically transfers a common load from a normal supply to an alternate supply in the event of failure of the normal supply, and automatically returns the load to the normal supply when the normal supply is restored. An automatic transfer switch can be provided with a logic control circuit that inhibits automatic operation of the device from either a normal to an alternate supply, or from an alternate to a normal supply when the switch reverts to automatic operation upon loss of power to the load.

1.5 A non-automatic transfer switch as covered by these requirements is a device, operated manually by a physical action, or electrically by a remote control, for transferring a common load between a normal and alternate supply.

1.6 These requirements only cover completely enclosed transfer switches.

Summary of Topics

The revision of ANSI/UL 1008A dated May 10, 2023 includes the following changes in requirements:

– Revisions to Table 16 to align with UL 347 up to 15 kV.

– Updates to service equipment requirements to align with 2020 NFPA 70; 23.1.1, 23.1A, 32.1 and Figure 4.