UL 1008S
Standard for Solid-State Transfer Switches

DETAILS
Edition Number:1SCC Approved:--
Edition Date:2012-11-15DOD Approved: --
Price Code:BANSI Approved: 2018-01-19
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements cover solid state automatic transfer switches intended for use in ordinary locations to provide for lighting and power only in optional stand-by systems in accordance with Article 702 of the National Electrical Code, ANSI/NFPA 70.

    1.2 Solid-state transfer switches are not for use as service entrance equipment unless marked as such.

    1.3 These requirements cover transfer switch equipment rated at 6000 A or less and 600 V or less.

    1.4 These requirements cover transfer switches together with their associated control devices including voltage sensing relays, frequency sensing relays, time delay relays, and the like.

    1.5 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 is allowed to 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.

    1.6 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.

    1.7 A transfer switch may incorporate overcurrent protection for the main power circuits.

    1.8 These requirements cover completely enclosed transfer switches and also open types intended for mounting in other equipment such as switchboards.

    1.9 Transfer switches are rated in amperes and are generally considered to be acceptable for total system transfer, which includes control of motors, electric-discharge lamps, electric-heating loads, and tungsten-filament lamp loads as referred to in 1.10.

    1.10 A transfer switch intended for total system transfer as indicated in 1.9 is considered to be acceptable for the control of tungsten-filament lamp loads not exceeding 30 percent of the switch ampere rating unless the switch has been investigated for a higher percentage of lamp load and marked accordingly.

    1.11 A transfer switch may be limited to use with one or more specific types of load if investigated accordingly and marked as indicated in 47.11.

  • TABLE OF CONTENTS
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    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 Components
          • 3 Units of Measurement
          • 4 Undated References
          • 5 Glossary
        • CONSTRUCTION
          • 6 General
          • 7 Enclosure
          • 8 Connections for Wiring Systems
          • 9 Corrosion Protection
          • 10 Insulating Material
          • 11 Bases
          • 12 Mounting of Parts
          • 13 Guarding and Accessibility of Live Parts
          • 14 Currrent-Carrying Parts
          • 15 Field Wiring Terminals
          • 16 Field Wiring Leads
          • 17 Conduit
          • 18 Inlets for Generator Connection
          • 19 Transfer Switches with Integral Inlets for Generator Connections
          • 20 Internal Wiring
          • 21 Grounding and Bonding
          • 22 Disconnecting Means
          • 23 Power Switch Assembly
          • 24 Ground-Fault Protection
          • 25 Transformer Grounding
          • 26 Spacings
          • 27 Wiring Space
          • 28 Protective Circuits
        • PERFORMANCE
          • 29 General
          • 30 Normal Operation Test
          • 31 Overload Test
          • 32 Temperature Test
          • 33 Endurance Test
          • 34 Dielectric Voltage-Withstand Test
          • 35 Withstand
          • 36 Receptacle Withstand
          • 37 Instrumentation and Calibration of High Capacity Circuits
            • 37.1 General
            • 37.2 Test circuit calibration
            • 37.3 Alternating current
            • 37.4 Galvanometers
          • 38 Closing
          • 39 Short-Time Current Rating Test (Optional)
          • 40 Dielectric Voltage-Withstand Test (Repeated)
          • 41 Strength of Insulating Base and Support
          • 42 Strain Relief Tests for Leads
          • 43 Conduit Hub Secureness Test
          • 44 Abnormal Operation
            • 44.1 General
            • 44.2 Inoperative blower motor
            • 44.3 Clogged filter
            • 44.4 Feed through protection
            • 44.5 Automatic overload bypass
        • MANUFACTURING AND PRODUCTION TESTS
          • 45 Ground-Fault Protection
        • RATINGS
          • 46 Details
        • MARKINGS
          • 47 Content
          • 48 Permanence of Marking
        • INSTALLATION TEST PROCEDURES
          • 49 Details
    • APPENDIX A