Preface 

This is the harmonized ANCE, CSA Group, and UL standard for Transfer Switch Equipment . It is the third edition of NMX-J-672-ANCE, the fourth edition of CSA C22.2 No. 178.1, and the ninth edition of UL 1008. This edition of NMX-J-672-ANCE supersedes the previous edition published on December 22, 2014 and revised on September 24, 2018. This edition of CSA C22.2 No. 178.1 supersedes the previous edition published on December 22, 2014 and revised on September 24, 2018. This edition of UL 1008 supersedes the previous edition published on December 22, 2014 and revised on September 24, 2018. This harmonized standard was prepared by the Association of Standardization and Certification, (ANCE), CSA Group and Underwriters Laboratories Inc. (UL). The efforts and support of the Technical Harmonization Subcommittee for Transfer Switches and the Council of the Harmonization of Electrotechnical Standards for the Nations of the Americas (CANENA), are gratefully acknowledged. This standard is considered suitable for use for conformity assessment within the stated scope of the standard. The present Mexican Standard was developed by the CT CDI Control y Distribución Industrial from the Comité de Normalización de la Asociación de Normalización y Certificación, A.C., CONANCE, with the collaboration of the transfer switch manufacturers and users. This standard was reviewed by the CSA Subcommittee on Automatic Transfer Switches, under the jurisdiction of the CSA Technical Committee on Industrial Products and the CSA Strategic Steering Committee on Requirements for Electrical Safety, and has been formally approved by the CSA Technical Committee. This standard has been developed in compliance with the Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. 

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: a) Automatic transfer switches; b) Manual or non-automatic transfer switches; c) Closed transition transfer switches; d) Hybrid transfer switches; e) Transfer switches for fire pumps; f) Bypass/isolating switches; g) Softload transfer switches; h) Transfer switches intended for use as service equipment; i) Transfer switches intended for use in mobile/portable applications such as recreational vehicles, motor homes, camping trailers, and mobile health care facilities; j) Inlet assemblies for transfer switch equipment; k) Arc resistant transfer switch equipment; l) Cord connected transfer switch equipment; m) Combination meter/transfer equipment assemblies; and n) In Mexico and the United States, branch circuit emergency lighting transfer switches (BCELTS). In Canada, the requirements for BCELTS do not apply. 

1.2 This standard specifically does not apply to: a) Double-throw switches for use in optional standby systems; b) Switches used in equipment manufactured in accordance with Annex A1, Item 9; c) In Canada, manually operated generator transfer panels in accordance with Annex A1, Item 12. d) Transfer switches rated over 1000 V; e) Solid-state (static) transfer equipment; f) Transfer switches for aircraft; and 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: a) Bypass/isolation switches (Annex D) b) Transfer switches for fire pump service (Annex E) c) Hybrid transfer switches (Annex F) d) Softload transfer switches (Annex G) e) Instrumentation and calibration of high capacity circuits (Annex H) f) Sample markings (Annex I) g) Inlet assemblies for transfer switch equipment (Annex J) h) Arc resistant transfer switch equipment (Annex K) i) Electromagnetic compatibility (EMC) requirements for transfer switches (Annex L) j) Cord connected transfer switch equipment (Annex M) k) Combination meter/transfer equipment assemblies (Annex N)