UL 1008 PDF

1 Scope

1.1 This standard applies to the following types of transfer switches that have a maximum rating of 1000 volts for use in non-hazardous locations, in accordance with Annex A1, Item 1:

1. a) Automatic transfer switches;

2. b) Manual or non-automatic transfer switches;

3. c) Closed transition transfer switches;

4. d) Hybrid transfer switches;

5. e) Transfer switches for fire pumps;

6. f) Bypass/isolating switches;

7. g) Softload transfer switches;

8. h) Transfer switches intended for use as service equipment;

9. i) Transfer switches intended for use in mobile/portable applications such as recreational vehicles, motor homes, camping trailers, and mobile health care facilities;

10. j) Inlet assemblies for transfer switch equipment;

11. k) Arc resistant transfer switch equipment;

12. l) Cord connected transfer switch equipment;

13. m) Combination meter/transfer equipment assemblies; and

14. n) In Mexico and the United States, branch circuit emergency lighting transfer switches (BCELTS).

15. In Canada, the requirements for BCELTS do not apply.

1.2 This standard specifically does not apply to:

1. a) Double-throw switches for use in optional standby systems;

2. b) Switches used in equipment manufactured in accordance with Annex A1, Item 9;

3. c) In Canada, manually operated generator transfer panels in accordance with Annex A1, Item 12.

4. d) Transfer switches rated over 1000 V;

5. e) Solid-state (static) transfer equipment;

6. f) Transfer switches for aircraft; and

7. g) Transfer switches for water craft.

1.3 These requirements apply to transfer switches and their associated control devices including voltage sensing relays, frequency sensing relays, time-delay relays, and the like.

1.4 These requirements apply to completely enclosed transfer switches and to open types intended for mounting in other equipment such as switchboards.

1.5 These requirements apply to bypass/isolation switches used to manually select an available power source to feed load circuits and to provide for total isolation of an automatic transfer switch. These switches may be completely enclosed, enclosed with the transfer switch, or of the open type intended for mounting in other equipment. Refer to Annex D.

1.6 In Canada, automatic transfer switches built to the optional standby requirements of this standard are not permitted. In Mexico and the United States, this requirement does not apply.

1.7 These requirements cover enclosed inlets intended to facilitate connection of portable generators to transfer equipment.

1.8 This Standard contains annexes with requirements to cover the following:

1. a) Bypass/isolation switches (Annex D)

2. b) Transfer switches for fire pump service (Annex E)

3. c) Hybrid transfer switches (Annex F)

4. d) Softload transfer switches (Annex G)

5. e) Instrumentation and calibration of high capacity circuits (Annex H)

6. f) Sample markings (Annex I)

7. g) Inlet assemblies for transfer switch equipment (Annex J)

8. h) Arc resistant transfer switch equipment (Annex K)

9. i) Electromagnetic compatibility (EMC) requirements for transfer switches (Annex L)

10. j) Cord connected transfer switch equipment (Annex M)

11. k) Combination meter/transfer equipment assemblies (Annex N)

Summary of Topics

This new edition of ANSI/UL 1008 dated July 13, 2022 includes the following changes:

– Marking Requirements– Scope of Annex J– Miscellaneous Updates– Table 2– Revised LSI Circuit Breaker Markings in Annex I– New Annex K for Arc Resistant Design– New Annex L for Electromagnetic Compatibility– Annex M for Cord Connected Transfer Switch Equipment– Marking/Instruction for Short Circuit Withstand Rating when Protected by Fuses– Revision of Requirements for Transfer Switches with Integral Inlets– Table 25– Changes to Align with the 2020 NEC– Revisions for Inlets Rated 100A and Greater for Compliance with the 2020 NEC– New Annex N for Combination Meter/Transfer Equipment Assemblies