UL 427
Standard for Refrigerating Units

DETAILS
Edition Number:5SCC Approved:--
Edition Date:2011-11-11DOD Approved: 1992-04-09
Price Code:BANSI Approved: 2017-02-10
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements cover refrigerating units intended for connection in accordance with the National Electrical Code, NFPA 70, to alternating-current (ac) circuits rated not greater than 600 volts.

    1.2 This standard also covers component refrigeration systems (self-contained mechanical refrigeration systems), not already covered by a UL standard, that heat, cool or dehumidify as integral (not stand-alone) components of appliances.

    1.3 Refrigerating units covered by these requirements employ sealed, hermetic-type motor compressors, and air- or water-cooled condensers.

    1.4 These requirements do not cover equipment intended for comfort cooling.

  • TABLE OF CONTENTS
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    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 General
            • 2.1 Units of measurement
            • 2.2 Terminology
            • 2.3 Undated references
          • 3 Glossary
        • CONSTRUCTION
          • 4 General
          • 5 Assembly
            • 5.1 General
            • 5.2 Electrical protection
          • 6 Accessories
          • 7 Enclosure
            • 7.1 General
            • 7.2 Openings
            • 7.3 Doors and covers
            • 7.4 Enclosures exposed to weather
          • 8 Field-Supply Connections
            • 8.1 Permanently connected equipment
            • 8.2 Field wiring compartment
            • 8.3 Cord-connected units
            • 8.4 Grounding
          • 9 Internal Wiring and Wiring Methods
            • 9.1 General
            • 9.2 High voltage circuits
            • 9.3 Low voltage circuits
            • 9.4 Wiring method
          • 10 Separation of Circuits
          • 11 Bonding for Grounding
        • ELECTRICAL COMPONENTS
          • 12 Capacitors
          • 13 Current-Carrying Parts
          • 14 Electric Defrost Heaters
          • 15 Fuseholders and Circuit Breakers
            • 15.1 Fuseholders
            • 15.2 Circuit breakers
          • 16 Fuses and Supplementary Protectors
          • 17 Insulating Material
          • 18 Motors
          • 19 Motor Overload Protection
            • 19.1 General
            • 19.2 Protection of single-phase nonhermetic motors
            • 19.3 Protection of three-phase motors
            • 19.4 Protection of hermetic refrigerant motor-compressors
          • 20 Switches and Controllers
          • 21 Transformers
          • 22 Valves and Solenoids
          • 23 Outlet Boxes, Electrical Cable, Conduit and Tubing
          • 24 Electromagnetic Interference Filters
          • 25 Relays and Contactors
          • 26 Optical Isolators and Semiconductor Devices
          • 27 Terminal Blocks
          • 28 Spacings
            • 28.1 High-voltage circuits
            • 28.2 Low-voltage circuits
          • 29 Alternate Spacings – Clearances and Creepage Distances
        • REFRIGERATION SYSTEM
          • 30 General
            • 30.1 Refrigerant
            • 30.2 Pump-down capacity
            • 30.3 Refrigerant tubing and fittings
          • 31 Refrigerant-Containing Parts
          • 32 Pressure-Limiting Device
          • 33 Pressure Relief
            • 33.1 General
            • 33.2 Relief valves
            • 33.3 Fusible plugs or rupture members
          • 34 Component Refrigeration Systems Integral to Other Appliances
        • PERFORMANCE
          • 35 General
            • 35.1 Temperature measurements
            • 35.2 Pressure measurements
            • 35.3 Test voltage
          • 36 Leakage Current Test – Cord Connected Refrigerating Units
          • 37 Input Test
          • 38 Starting Test
          • 39 Temperature and Pressure Test
          • 40 Defrost Test
          • 41 Dielectric Voltage-Withstand Test
          • 42 Condenser Fan Motor Failure Test
          • 43 Condenser Water Failure Test
          • 44 Overflow Test
          • 45 Rain Test
          • 46 Strain Relief Test
          • 47 Static Loading Test
          • 48 Endurance Test – Defrost Heater Control
          • 49 Burnout Test
          • 50 Overvoltage and Undervoltage Tests
          • 51 Current Overload Test – Bonding Conductors and Connections
          • 52 Insulation Resistance Test
          • 53 Limited Short-Circuit Test
            • 53.1 General
            • 53.2 Motor overload protective devices
            • 53.3 Bonding conductors and connections
            • 53.4 Motor circuit conductors and connections
          • 54 Maximum Continuous Current Test
          • 55 Strength Tests
          • 56 Fastener Retainer Test
          • 57 Accelerated Aging Test – Electric Heater
          • 58 Reliability Test – Heater Termination
          • 59 Accelerated Aging Tests on Gaskets, Sealing Compounds, and Adhesives
            • 59.1 General
            • 59.2 Sealing compound
            • 59.3 Adhesives
          • 60 Chromic Acid Dropping Test
          • 61 Burnout Tests – Electromagnetic Components
        • MANUFACTURING AND PRODUCTION TESTS
          • 62 General
          • 63 Production Line Dielectric Voltage-Withstand Tests
        • MARKING
          • 64 General
          • 65 Refrigerant Markings
          • 66 Permanently Connected Equipment
          • 67 Cord Connected Units
          • 68 Cautionary Markings
          • 69 Accessory Markings
        • INSTRUCTIONS
          • 70 Installation and Operating Instructions
    • REQUIREMENTS FOR REFRIGERATING UNITS EMPLOYING A FLAMMABLE REFRIGERANT IN THE REFRIGERATING SYSTEM