UL 1996
Standard for Electric Duct Heaters

DETAILS
Edition Number:4SCC Approved:--
Edition Date:2009-08-31DOD Approved: --
Price Code:BANSI Approved: 2016-07-14
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements cover fixed electric duct heaters, and remote control assemblies for such equipment, rated at 600 volts or less to be employed in ordinary locations in accordance with the National Electrical Code, ANSI/NFPA 70.

    1.2 These requirements do not cover fan-coil units, central heating furnaces, panel or cable type radiant heating equipment, electric boilers, baseboard heaters, air heaters, nor any other electric heating equipment or appliances which are covered in or as a part of separate, individual requirements.

    1.3 Duct heaters intended for use in a hazardous location are judged on the basis of its compliance with the requirements in this standard, together with the requirements for hazardous location equipment included in other applicable standards.

    1.4 Duct heaters designed to be connected to air-duct systems are intended for installation in accordance with the Standard for the Installation of Air Conditioning and Ventilating Systems, NFPA 90A, and the Standard for the Installation of Warm Air Heating and Air Conditioning Systems, NFPA 90B.

    1.5 These requirements apply to relays and other auxiliary control devices that may be provided as part of a duct heater to make it usable with other heating or cooling equipment, and are intended to take into account the effects of operating the duct heater in conjunction with or in proximity to such equipment.

    1.6 A duct heater is a self-contained heater designed to be installed in the field in the air stream of a ducted system, external to the air-moving unit. It is designed to be installed in a duct where an adequate flow of air from a separate, interlocked fan or blower system is provided. Such a heater may be located in the main supply duct of an air heating system, or in one of the branch ducts. Two or more duct heaters may be installed in a group (in proximity to one another in the duct) if tests indicate acceptable results when the heaters are installed in accordance with the manufacturer's instructions.

    1.7 A duct heater intended to be employed in conjunction with another source of heat is judged on the basis of its compliance with the requirements in this standard, and further examination and tests to determine whether or not the combination is acceptable.

  • TABLE OF CONTENTS
    Expand All

    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 General
            • 2.1 General
            • 2.2 Terminology
            • 2.3 Units of measurement
            • 2.4 Undated references
          • 2A Glossary
          • 3 Components
            • 3.1 General
            • 3.2 Attachment plugs, receptacles, connectors, and terminals
            • 3.3 Electrical enclosures and raceways
            • 3.4 Cords, cables, and internal wiring
            • 3.5 Lampholders
            • 3.6 Power supplies
            • 3.7 Printed wiring boards
            • 3.8 Controls
        • CONSTRUCTION
          • 4 Enclosures
          • 5 Thickness of Sheet Metal Enclosures for Uninsulated Live Parts
          • 6 Openings in Enclosures
          • 7 Enclosures, Doors, and Covers
          • 8 Accessibility of Parts
          • 9 Assembly
          • 10 Outdoor Use Equipment
            • 10.1 General
            • 10.2 Enclosures
            • 10.3 Field wiring connections
          • 11 Mechanical Assembly
          • 12 Auxiliary Devices
          • 13 Connection to Power Supply
          • 14 Thermal Insulation and Air Filters
          • 15 Terminal Parts and Leads for Field Wiring Connections
            • 15.1 General
            • 15.2 High-voltage circuits
            • 15.3 Low-voltage circuits
          • 16 Internal Wiring
          • 17 Separation of Circuits
          • 18 Electrical Insulation
          • 19 Grounding and Bonding
          • 20 Mounting of Components
          • 21 Switches and Fan Controllers
          • 22 Transformers
          • 23 Electric Heaters
            • 23.1 General
            • 23.2 Overcurrent protection
            • 23.3 Heater controls
          • 24 Control Circuits
          • 24A Controls
            • 24A.1 End product test parameters
            • 24A.2 Auxiliary controls
            • 24A.3 Operating controls (regulating controls)
            • 24A.4 Protective controls (limiting controls)
            • 24A.5 Controls using a temperature sensing device
          • 24B UL 60335-1 BASED REQUIREMENTS FOR THE EVALUATION OF ELECTRONIC CIRCUITS
            • 24B.1 Introduction
            • 24B.2 Construction
            • 24B.3 Performance
            • 24B.4 Manufacturing and production line testing
            • 24B.5 Appendix
          • 25 Moisture
          • 26 Spacings
            • 26.1 Hazardous voltage circuits
            • 26.2 Low-voltage circuits
          • 26A Clearance and Creepage Distances
        • PERFORMANCE
          • 27 General
            • 27.1 General
            • 27.2 Supply connections
            • 27.3 Airflow
            • 27.4 Inlet air
            • 27.5 Outlet air
            • 27.6 Test enclosure
          • 28 Temperature Tests
          • 29 Power Input
          • 30 Limit Control Cutout Test
          • 31 Normal Tests
            • 31.1 Continuous operation
            • 31.2 Nuisance tripping
            • 31.3 Fan-delay control
          • 32 Abnormal Tests
            • 32.1 General
            • 32.2 Restricted inlet
            • 32.3 Fan failure
            • 32.4 Blocked outlet
          • 33 Backup Protection Tests
            • 33.1 General
            • 33.2 Restricted inlet
            • 33.3 Fan failure
            • 33.4 Blocked outlet
          • 34 Solid-State Components Test
          • 35 Dielectric Voltage-Withstand Test
          • 36 Insulation Resistance
          • 37 Short-Circuit Tests
          • 38 Overload Test – High-Voltage Transformers
          • 39 Burnout Test – High-Voltage Transformers
          • 40 Rain Test
          • 41 Gaskets – Accelerated Aging Tests
        • MANUFACTURING AND PRODUCTION TESTS
          • 42 Knockout Security Test
          • 43 Production Line Dielectric Voltage-Withstand Tests
        • MARKING
          • 44 General
          • 45 Equipment Markings
            • 45.1 General
            • 45.2 Determination of rating
          • 46 Other Markings
        • INSTRUCTIONS
          • 47 General
    • APPENDIX A(informative)