UL 923
Standard for Microwave Cooking Appliances

DETAILS
Edition Number:7SCC Approved:--
Edition Date:2013-05-01DOD Approved: 1990-06-29
Price Code:CANSI Approved: 2019-02-13
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements cover household and commercial microwave cooking appliances operated in the Industrial, Scientific and Medical (ISM) bands of 915 ±25 and 2450 ±50 MHz, for use in ordinary locations in accordance with the National Electrical Code, NFPA 70, and rated not more than 600 V.

    1.2 These requirements also cover microwave cooking appliances intended for built-in installation, side-by-side mounting, stacking, wall mounting and installation over ranges.

    1.3 For the purpose of these requirements, commercial microwave cooking equipment is that usually found in commercial kitchens, restaurants, or other business establishments where food may be dispensed. Household microwave cooking equipment is that intended for household use.

    1.4 These requirements also cover the microwave cooking portion of a household electric range. The combination is to comply with the Standard for Household Electric Ranges, UL 858.

  • TABLE OF CONTENTS
    Expand All

    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 Glossary
        • CONSTRUCTION
          • 3 General
          • 4 Components
          • 5 Frame and Enclosure
          • 6 Accessibility of Live Parts
          • 7 Protection Against Injury
            • 7.1 General
            • 7.2 Strength of mounting
            • 7.3 Fans
          • 8 Mechanical Assembly
          • 9 Protection Against Corrosion
          • 10 Interlocks
          • 11 Interlock Monitors
          • 12 Polymeric Materials
          • 13 Supply Connections
            • 13.1 Permanently-connected appliances
            • 13.2 Cord-connected appliances
          • 14 Live Parts
          • 15 Polarization
          • 16 Internal Wiring
            • 16.1 General
            • 16.2 Splices and connections
          • 17 Heating Elements
          • 18 Electrical Insulation
            • 18.1 General
            • 18.2 Printed wiring board
            • 18.3 Film-coated wire (magnet wire)
            • 18.4 Insulation systems
          • 19 Thermal Insulation
          • 20 Motors
          • 21 Motor Overload Protection
          • 22 Short-Circuit and Ground-Fault Protection
            • 22.1 General
            • 22.2 Motors and power transformers
            • 22.3 Receptacles
          • 23 Thermostats
          • 24 Thermal Cutoffs
          • 25 Attachment-Plug Receptacles
          • 26 Lampholders
          • 27 Switches and Controls
            • 27.1 General
            • 27.2 Power output control circuits
          • 28 Protective controls (Limiting controls) – End Product Test Parameters
          • 29 Filters
          • 30 Spacings
          • 31 Grounding
          • 32 Secondary Circuits
            • 32.1 General
            • 32.2 Connections to frame
            • 32.3 Separation of circuits
          • 33 Transformers
          • 34 Batteries and Battery Charging Circuits
          • 35 Capacitors
          • 36 Light Sources and Associated Components
          • 36A Child Resistant Oven Door
            • 36A.1 General
            • 36A.2 Door handle force test
            • 36A.3 Override for single-action door opening
        • PERFORMANCE
          • 37 General
          • 38 Leakage Current Test
          • 39 Microwave Radiation Emission Test
            • 39.1 General
            • 39.2 Instrumentation
            • 39.3 Cavity load
            • 39.4 Supply voltage
            • 39.5 Microwave radiation emission measurement
          • 40 Power Input Test
            • 40.1 General
            • 40.2 Supply voltage
            • 40.3 Cavity load
            • 40.4 Oven operation
          • 41 Temperature Test
            • 41.1 General
            • 41.2 Temperature measurements
            • 41.3 Installation
            • 41.4 Supply voltage
            • 41.5 Cavity load
            • 41.6 Operating conditions
            • 41.7 Motors used with solid-state controls
          • 42 Surface Temperature Tests
            • 42.1 General
            • 42.2 Measurement of surfaces
            • 42.3 Measurement of handles and knobs
            • 42.4 Over-the-cooktop appliances
          • 43 Insulation Resistance and Leakage Current Test as a Result of Moisture
          • 44 Dielectric Voltage-Withstand Test
            • 44.1 General
            • 44.2 Primary circuits
            • 44.3 Secondary circuits
          • 45 Door Assembly Tests
            • 45.1 Door operation
            • 45.2 All doors
            • 45.3 Side-hinged doors
            • 45.4 Bottom-hinged doors
            • 45.5 Impact tests
          • 46 Glass Control Panel Test
          • 47 Metal Enclosure Impact Test
          • 48 Interlock System Endurance Test
            • 48.1 General
            • 48.2 Appliance connections
            • 48.3 Test equipment
            • 48.4 Operating sequence
          • 49 Interlock Monitor Circuit Test
          • 50 Mechanical Endurance Test
          • 51 Moisture Conditioning Test
          • 52 Spill Test
          • 53 Spill Test for Horizontally-Mounted Openings
          • 54 Abnormal Operation Tests
            • 54.1 General
            • 54.2 Appliance connections
            • 54.3 Appliance configuration
            • 54.4 Test duration
            • 54.5 Shorted thermostat test
          • 55 Abnormal Operation Tests on Motors Used With Solid-State Controls
          • 56 Abnormal Operation – Fire Isolation Test
          • 57 Magnetically Operated Interlock Test
          • 58 X-Radiation Test
            • 58.1 General
            • 58.2 X-radiation under servicing conditions
          • 59 Temperature Control Tests
          • 60 Temperature Probe Test
          • 61 Motor Switch Test
          • 62 Interlock Malfunction Test
          • 63 Salt Spray Corrosion Test
          • 64 Cavity Fire Containment Test
          • 64A Forced Failure Fire Containment Tests
            • 64A.1 General
            • 64A.2 Potato fire containment test
            • 64A.3 Waveguide and stirrer fire containment test
            • 64A.4 Popcorn fire containment test
            • 64A.5 Thermally protected AC fan motor ignition test
            • 64A.6 Nichrome wire ignition tests
          • 65 Strength of Mounting Test
          • 66 Tests on Motors Exposed to Grease or Cooking Vapors
            • 66.1 General
            • 66.2 Grease conditioning
            • 66.3 Oven and humidity conditioning
        • MANUFACTURING AND PRODUCTION-LINE TESTS
          • 67 Dielectric Voltage-Withstand Test
          • 68 Grounding-Continuity Test
        • RATING
          • 69 Details
        • MARKINGS
          • 70 General
          • 71 Visible After Installation
            • 71.1 General
            • 71.2 Combination microwave oven hood fans
          • 72 Visible to the User During Use
          • 73 Visible During Installation and Examination
          • 74 Instruction Manuals
          • 75 Important Safety Instructions
            • 75.1 General
            • 75.2 Over-the-cooktop microwave ovens
            • 75.3 Microwave oven-vent hood fans
            • 75.4 Self-cleaning appliances
          • 76 Warning Markings and Instructions Concerning Microwave and X-Radiation Emission
          • 77 Grounding Instructions
        • SELF-CLEANING OVENS
          • GENERAL
          • 78 Scope
          • CONSTRUCTION
          • 79 Materials
            • 79.1 Oven coating
            • 79.2 Smoke eliminators
            • 79.3 Oven vent tubes and smoke diverters
          • 80 Oven Door Latch/Interlock Assembly
          • 81 Seals and Gaskets
          • PERFORMANCE
          • 82 General
          • 83 Temperature Test
            • 83.1 General
            • 83.2 Normal temperature
          • 84 Latch-Solenoid Temperature Test
          • 85 Shorted Thermostat – Abnormal Test
          • 86 Oven-Door Latch Endurance Test
          • 87 Window Impact Tests
          • FIRE AND EXPLOSION
          • 88 General
          • 89 Test Electrodes
          • 90 Test Samples
          • 91 Installation of Test Sample
          • 92 Fire and Explosion Test Within Oven
          • 93 Emission of Carbon Monoxide
          • 94 Vent Gases and Vapors Test
          • 95 Vertical Cool-Air-Mixing Duct Test
          • 96 Self-Cleaning of Removable Companion Oven Panels Test
          • 97 Elevated Interlock Operating Temperature Tests
          • MARKING
          • 98 Details
    • SAFETY OF SMART ENABLED MICROWAVE COOKING APPLIANCES