UL 508A
Standard for Industrial Control Panels

DETAILS
Edition Number:2SCC Approved:--
Edition Date:2013-12-20DOD Approved: --
Price Code:CANSI Approved: --
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements cover industrial control panels intended for general industrial use, operating from a voltage of 1000 volts or less. This equipment is intended for installation in ordinary locations, in accordance with the National Electrical Code, ANSI/NFPA 70, where the ambient temperature does not exceed 40°C (104°F) maximum.

    1.2 These requirements also cover industrial control panel enclosures and industrial control panels primarily intended for flame safety supervision of combustible fuel type equipment, elevator control, crane or hoist control, service equipment use, marine use, air conditioning and refrigeration equipment, equipment for load management applications, fountain control, irrigation equipment control, and for control of industrial machinery including metalworking machine tools, power press controls, and plastic injection molding machinery. Also covered are industrial control panels intended for control of permanently installed electrical equipment for aquatic playgrounds, permanently installed electrical equipment associated with commercial water park rides, wave pools and similar installations, and permanently installed electrical equipment associated with commercial and large residential swimming pools and in-ground spas.

    1.3 This equipment consists of assemblies of two or more power circuit components, such as motor controllers, overload relays, fused disconnect switches, and circuit breakers, or control circuit components, such as pushbuttons, pilot lights, selector switches, timers, and control relays, or a combination of power and control circuit components, with associated wiring, and terminals . These components are mounted on, or contained within, an enclosure, or are mounted on a sub-panel.

    1.4 An industrial control panel does not include an evaluation of the controlled equipment such as motors, heaters, lighting, and other loads connected to power circuits. Unless specifically noted on the wiring diagram of the industrial control panel, an industrial control panel does not include equipment mounted remotely from the panel and connected via a wiring systems or equipment field installed on or within the industrial control panel.

    1.5 An evaluation of the adequacy of the controls and protective devices contained in an industrial control panel for supervision and proper functioning of the controlled loads or equipment is not covered by the requirements in this standard. Such evaluations are covered by the standards applicable to the complete piece of utilization equipment.

    1.6 The evaluation of a pre-fabricated building, structure, or platforms supplied with industrial control panels are not covered by the requirements in this standard.

    1.7 Fire pump controllers are covered by the Standard for Fire Pump Controllers, UL 218.

    1.8 Equipment intended for use in hazardous locations, as defined in the National Electrical Code, ANSI/NFPA 70, are covered by the Standard for Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous (Classified) Locations, UL 1203.

    1.9 Industrial control panels incorporating intrinsic safety barriers and intended for connection to circuits residing in hazardous locations are covered by the Standard for Industrial Control Panels Relating to Hazardous (Classified) Locations, UL 698A.

    1.10 Motor control centers, including motor control center sections and units, or equipment intended for field installation into a motor control center are covered by the Standard for Motor Control Centers, UL 845.

    1.11 Assemblies of electrical control units or equipment containing electrical control units for fire-protective signaling systems are covered by the Standard for Control Units and Accessories for Fire Alarm Systems, UL 864.

    1.12 A freestanding assembly of circuit breakers and busses for control of electric light and power circuits or equipment intended for field installation in dead-front switchboards are covered by the Standard for Switchboards, UL 891.

    1.13 Equipment intended to supply automatic illumination, power, or both, to critical areas and equipment essential to safety of human life is covered by the Standard for Emergency Lighting and Power Equipment, UL 924.

    1.14 Control equipment for use with swimming pools and spas is covered by the Standard for Electric Spas, Equipment Assemblies, and Associated Equipment, UL 1563.

    1.15 Portable control panels containing switches, overcurrent protection, and cord connected via attachment plugs and receptacles for use at carnivals, circuses, fairs, exhibition halls, motion picture and television studios, theaters, construction sites and similar locations are covered by the Standard for Portable Power-Distribution Equipment, UL 1640.

    1.16 Equipment for the control of fuel cells, photovoltaic systems, or utility interactive systems are covered by the Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources, UL 1741.

    1.17 Enclosures or pedestals containing terminals for connection of power circuit conductors are covered by the Standard for Termination Boxes, UL 1773.

    1.18 Emergency alarm equipment or control panels containing emergency alarm equipment are covered by the Standard for General-Purpose Signaling Devices and Systems, UL 2017.

    1.19 Equipment for gas or vapor detection or control panels containing gas or vapor detection equipment is covered by the Standard for Gas and Vapor Detectors and Sensors, UL 2075.

    1.20 Control panels containing predominately communication equipment, such as telephone equipment and intended for installation in accordance with Chapter 8 of the NEC, is evaluated to the Standard for Information Technology Equipment – Safety – Part 1: General Requirements, UL 60950-1.

    1.21 Control equipment intended for use in physical access control systems, which provide an attended or unattended means of monitoring or controlling traffic through portals of a protected area for security purposes; or in key management systems, which regulate or control access to the use of a device by electrical, electronic or mechanical means, are covered by the Standard for Access Control System Units, UL 294.

    1.22 Electrically operated or mechanically operated control equipment or enclosures intended for theft deterrent or warning purposes, such as detectors, security containers or alarms for merchandise or property, are covered by the Standard for Antitheft Alarms and Devices, UL 1037.

    1.23 Equipment primarily intended to energize or de-energize electrical loads to achieve the desired use of electrical power is covered by the Standard for Energy Management Equipment, UL 916. Such equipment is intended to control electrical loads by responding to sensors or transducers monitoring power consumption, by sequencing, by cycling the loads through the use of preprogrammed data logic circuits, or any combination thereof.

  • TABLE OF CONTENTS
    Expand All

    • Cover
    • Transmittal
    • Table of Contents
      • Body
        • PART 1 – GENERAL USE INDUSTRIAL CONTROL PANELS
          • INTRODUCTION
          • 1 Scope
          • 2 Glossary
          • 3 Undated References
          • 4 Components
          • 5 Units of Measurement
          • 6 Terminology
          • CONSTRUCTION
            • ALL PANELS
          • 7 General
          • 8 Protection Against Corrosion
          • 9 Support and Securement of Live Parts
          • 10 Spacings
          • 11 Conduit Bushings
          • 12 Insulating Barriers
          • 13 Insulating Materials
          • 14 Grounding – General
          • 15 Grounding – Size of Terminal or Bonding Conductor
          • 16 Transformer and Power Supply Secondary Grounding
          • 17 Identification of Grounding and Grounded Circuit Conductors and Terminals
            • ENCLOSED PANELS
          • 18 Enclosures
          • 19 Enclosure Openings
          • 20 Accessibility of Live Parts
          • 21 Ventilation Openings
            • 21.1 General
            • 21.2 Location of ventilation opening
            • 21.3 Construction
          • 22 Barriers Used with Ventilation Openings
          • 23 Observation Windows
          • 24 Bonding
          • 25 Wire Bending Space
          • 26 Enclosure Environmental Control Devices
            • 26.1 General
            • 26.2 Enclosure fans
            • 26.3 Enclosure air conditioner
            • 26.4 Enclosure heater
            • 26.5 Air filters
            • 26.6 Enclosure thermal insulation
          • 27 Enclosure Maintenance Lighting
            • 27.1 General
            • 27.2 Component requirements
            • 27.3 Circuit requirements
            • POWER CIRCUITS
          • 28 Field Wiring
            • 28.1 General
            • 28.2 Component requirements
            • 28.3 Sizing
            • 28.4 Separation of circuits
            • 28.5 Cord-connected equipment
            • 28.6 Receptacles
          • 29 Internal Wiring
            • 29.1 General
            • 29.2 Conductor requirements
            • 29.3 Wiring methods
            • 29.4 Routing of internal wiring
            • 29.5 Separation of circuits
            • 29.6 Sizing
          • 30 Disconnect Switches
            • 30.1 Component requirements
            • 30.2 Sizing of disconnect switch
            • 30.3 Location
            • 30.4 Mechanical operating mechanism
          • 31 Branch Circuit Protection
            • 31.1 Component requirements
            • 31.2 Location
            • 31.3 Sizing of branch circuit protection for single motor circuit
            • 31.4 Sizing of branch circuit protection for motor groups
            • 31.5 Receptacles
            • 31.6 Sizing of branch circuit protection for heater loads
            • 31.7 Sizing of branch circuit protection for appliance loads
            • 31.8 Sizing of branch circuit protection for lighting loads
          • 32 Overcurrent Protection of Feeder
            • 32.1 Component requirements
            • 32.2 Location
            • 32.3 Sizing of overcurrent protection
            • 32.4 Feeder taps for non-motor loads
            • 32.5 Feeder taps for motor loads
          • 33 Load Controllers
            • 33.1 Component requirements
            • 33.2 Sizing/rating of load controllers
            • 33.3 Location
            • 33.4 Reversing motor controllers
            • 33.5 Wye-delta motor controllers
            • 33.6 Controllers for multi-speed and part winding motors
            • 33.7 Autotransformer- and resistor-type reduced voltage motor controllers
          • 34 Overload Protection of Motor Loads
            • 34.1 Component requirements
            • 34.2 Sizing of overload relay
            • 34.3 Location
          • 35 Power Transformers
            • 35.1 Component requirements
            • 35.2 Sizing of overcurrent protection for power transformer
            • 35.3 Location
          • 36 Other Circuit Components
            • 36.1 Capacitors
            • 36.2 Resistors
            • 36.2A Reactors
            • 36.3 Surge control devices
            • CONTROL CIRCUITS
          • 37 Field Wiring Terminals
            • 37.1 Component requirements
            • 37.2 Sizing
            • 37.3 Field wiring terminals of a low-voltage limited energy circuit
            • 37.4 Field wiring terminals of Class 2 circuits
            • 37.5 Separation of circuits
            • 37.6 Receptacles
            • 37.7 Flexible cords
          • 38 Internal Wiring
            • 38.1 Component requirements
            • 38.2 Sizing of internal control circuit conductors
            • 38.3 Wiring methods, wire routing, and separation of circuits for internal wiring of a control circuit
          • 39 Disconnecting Means
          • 40 Overcurrent Protection
            • 40.1 Component requirements
            • 40.2 Location of overcurrent protective devices
            • 40.3 Sizing of overcurrent protection
          • 41 Sizing of Overcurrent Protection – Control Circuits (Common)
          • 42 Overcurrent Protection – Control Circuits (Isolated Secondary)
            • 42.1 Control transformers
            • 42.2 Power supplies
            • 42.3 Other isolated secondary sources
          • 43 Low-Voltage Limited Energy Circuits
            • 43.1 Component requirements
            • 43.2 Secondary side requirements
          • 44 Class 2 Circuits
            • 44.1 Component requirements
            • 44.2 Secondary side requirements
          • 45 Switching Devices
            • 45.1 Component requirements
            • 45.2 Sizing/ratings of control circuit switching devices
            • 45.3 Location
            • 45.4 Undervoltage protection
          • 46 Loads
            • 46.1 Component requirements
            • 46.2 Location
            • 46.3 Rating of control circuit load
          • 47 Miscellaneous Devices
            • 47.1 Surge control devices
            • 47.2 Resistors
          • 48 Pneumatic Switching Devices
          • RATING
          • 49 Supply Ratings
          • 50 Individual Load Ratings
          • 51 Ratings for Control Circuit Outputs
          • MARKINGS
          • 52 General Markings
          • 53 Enclosure Markings
          • 54 Field Wiring Terminal Markings
          • 55 Cautionary Markings
          • 56 Fuseholder Markings
          • 57 Switch Markings
          • 58 Overload Relay Heater Table Markings
          • 59 Receptacle Markings
          • 60 Field Provided Components
          • 61 Schematic Wiring Diagrams
        • PART 2 – SPECIFIC USE INDUSTRIAL CONTROL PANEL TYPES
          • ENCLOSURES
          • 62 General
          • 63 Construction
            • 63.1 Metal thickness
            • 63.2 Covers and doors
            • 63.3 Corrosion protection
            • 63.4 Enclosure openings
            • 63.5 Ventilation openings
            • 63.6 Observation windows
          • 64 Markings
          • INDUSTRIAL MACHINERY
          • 65 General
          • 66 Construction
            • 66.1 Enclosures
            • 66.2 Electrical assembly
            • 66.3 Grounding
            • 66.4 Field wiring – power circuits
            • 66.5 Internal wiring – power circuits
            • 66.6 Disconnecting means
            • 66.7 Branch circuit protection
            • 66.8 Motor controllers
            • 66.9 Internal wiring of control circuit
            • 66.10 Overcurrent protection of common control circuit
            • 66.11 Operator controls
          • 67 Markings
            • 67.1 Nameplate markings
            • 67.2 Operator controls
            • 67.3 Components
            • 67.4 Cautionary marking
          • CRANE CONTROL
          • 68 General
          • 69 Glossary
          • 70 Construction
            • 70.1 Field wiring terminals of power circuits
            • 70.2 Internal wiring
            • 70.3 Disconnecting means
            • 70.4 Branch circuit protection
            • 70.5 Motor overload protection
            • 70.6 Field wiring of control circuits
            • 70.7 Overcurrent protection of control circuit
          • 71 Ratings
          • 72 Markings
          • SERVICE EQUIPMENT USE
          • 73 General
          • 74 Glossary
          • 75 Construction
            • 75.1 Grounding and bonding
            • 75.2 Spacings
            • 75.3 Field wiring terminals
            • 75.4 Disconnecting means
            • 75.5 Neutral disconnecting means
            • 75.6 Ground-fault protection
            • 75.7 Overcurrent protection
            • 75.8 Components on the supply side of the disconnecting means
          • 76 Ratings
          • 77 Markings
            • 77.1 Bonded neutral
            • 77.2 Insulated neutral
            • 77.3 Marking location
            • 77.4 Disconnects
            • 77.5 Ground-fault protection
          • 78 Installation Instructions
          • 79 Tests By The Manufacturer – Ground-Fault Protection Test
          • ELEVATOR CONTROL
          • 80 General
          • FLAME CONTROL
          • 81 General
          • 82 Construction
            • 82.1 Component requirements
            • 82.2 Spacings
            • 82.3 Internal wiring
            • 82.4 Location
            • 82.5 Separation of circuits
            • 82.6 Overcurrent protection
          • 83 Marking
          • MARINE USE
          • 84 General
          • 85 Construction
            • 85.1 Enclosures
            • 85.2 Autotransformer starters
            • 85.3 Insulating materials
            • 85.4 Branch circuit overcurrent devices
          • 86 Ratings
          • 87 Markings
          • AIR CONDITIONING AND REFRIGERATION EQUIPMENT
          • 88 General
          • 89 Glossary
          • 90 Construction
            • 90.1 Field wiring sizing – power circuit
            • 90.2 Disconnecting switches – power circuits
            • 90.3 Branch circuit protection sizing – power circuits
            • 90.4 Load controllers – power circuits
          • 91 Ratings
          • 92 Marking
          • FOUNTAIN CONTROL PANELS
          • 93 General
          • 94 Construction
            • 94.1 Grounding
            • 94.2 Ground – fault protection
            • 94.3 Equipotential bonding
            • 94.4 Cord strain relief
          • 95 Ratings
          • 96 Marking
          • INDUSTRIAL CONTROL PANELS FOR IRRIGATION EQUIPMENT
          • 97 General
          • 98 Construction
            • 98.1 Sizing of motor controller
            • 98.2 Disconnecting means
            • 98.3 Branch circuit protection
            • 98.4 Internal conductors
          • 99 Marking
          • CONTROL PANELS FOR AQUATIC PLAYGROUNDS
          • 100 General
          • 101 Glossary
          • 102 Construction
            • 102.1 Grounding
            • 102.2 Ground-fault protection
            • 102.3 Transformers and power supplies
          • 103 Ratings
          • 104 Marking
          • CONTROL PANELS FOR SWIMMING POOLS AND IN-GROUND SPAS
          • 105 General
          • 106 Glossary
          • 107 Construction
            • 107.1 General
            • 107.2 Grounding
            • 107.3 Ground-fault protection
            • 107.4 Luminaire transformers and power supplies
            • 107.5 Cord strain relief
          • 108 Ratings
          • 109 Markings
          • CONTROL PANELS FOR WATER PARK RIDES AND SIMILAR INSTALLATIONS
          • 110 General
          • 111 Glossary
          • 112 Construction
            • 112.1 General
            • 112.2 Grounding of wave pools
            • 112.3 Sensors
            • 112.4 Ground– fault protection
            • 112.5 Luminaire transformers and power supplies
          • 113 Ratings
          • 114 Marking
    • SHORT CIRCUIT CURRENT RATINGS FOR INDUSTRIAL CONTROL PANELS
    • APPENDIX A
    • APPENDIX B