1 Scope

1 1.1 This standard is applicable to ac contactors applied at voltages in the range of 1 501V to 15kV, and metal-enclosed contactor-based controllers, control centers, and other control assemblies and associated equipment applied at voltages in the range of 751V to 15kV, designed for operation at frequencies of 50 or 60 Hz on three-phase systems. These requirements apply to equipment intended for use in ordinary (non-hazardous) locations and installed in accordance with the applicable local installation codes and standards (see Annex A, Item 1). These requirements, as modified by the applicable national standards for fire pump controllers, also apply to fire pump controllers (see Annex A, Item 2).

1 1.2 This standard also includes requirements for controllers intended for service entrance applications. (See Annex A, Item 3 and Clause 204.)

1 1.3 This standard also includes requirements for equipment incorporating solid state switching elements intended for starting, stopping, regulating, controlling, or protecting heating and other resistive loads, having ac voltage ratings in the range of 1501V to 15kV.

1 1.4 This standard also includes requirements for reduced-voltage solid-state controllers.

1 1.5 This standard does not apply to:

1. a) equipment for use in classified (hazardous) locations as defined in the applicable installation codes or standards;

2. b) components contained in contactors and contactor-based controllers for which individual component standards exist;

3. c) auxiliary low voltage control assemblies (see Annex A, Item 4);

4. d) equipment consisting solely of electronic or solid-state devices, circuits, or systems;

5. e) electronic variable speed motor controllers (power conversion equipment); and

6. f) controllers using only solid-state devices in the main circuit.

Summary of Topics

This revision of ANSI/UL 347 dated February 3, 2025 includes the following changes in requirements:

– Grounding switch interlock test: 4.206, 5.11.201, 5.11.207, and 6.101.3;

– Field wiring in equipment designed for use with MV 90 cable: 5.10.204