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UL Standards

Electrical enclosures

Boxes -- Junction and Pull (BGUZ)

Products Listed under this category include sheet metal boxes, cast metal boxes, and nonmetallic boxes. All boxes in this category have a volume of more than 100 cu. in.

  • PVC junction and pull boxes are suitable for use with PVC rigid nonmetallic conduit. Such boxes are inherently resistant to atmospheres containing common industrial corrosive agents and will also withstand vapors or mists of caustics, pickling acids, plating baths, hydrofluoric and chromic acids.
  • Cast metal boxes suitable for field drilling and tapping of holes for conduit connections and mounting are marked to indicate the location and the trade sizes of the openings either on the box or on the packaging carton.
  • Cast-aluminum boxes suitable for use in concrete or cinder fill are marked to indicate this fact either on the box or on the packaging carton.

The basic standard used to investigate this category is UL 50, Standard of Safety for Enclosures for Electrical Equipment.

Cabinets and Cutout Boxes--Sheet Metal (CYIV)

Products Listed under this category include sheet metal boxes and nonmetallic boxes. The basic standard used to investigate this category is UL 50, Standard of Safety for Enclosures for Electrical Equipment.

Industrial Control Panel Enclosures (NITW)

Products Listed under this category include enclosures that are intended to house open type industrial control panels.

The basic standards used to investigate this category is UL 508A, the Standard of Safety for Industrial Control Panels, UL 508, the Standard of Safety for Industrial Control Equipment, and UL 50, the Standard of Safety for Enclosures for Electrical Equipment.

Industrial control panels

Industrial Control Panels (NITW)

Products Listed under this category include industrial control panels, which are factory wired assemblies of industrial control equipment such as motor controllers, switches, relays and auxiliary devices. The panels may include disconnect means and motor branch circuit protective devices. This category also covers industrial panel enclosures that are intended to house open type industrial control panels or individual items of industrial control equipment as noted above.

The basic requirements used to investigate this category are contained in UL 508A, the Standard of Safety for Industrial Control Panels.

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Flame Control Panels (NITW)

Products Classified under this category include flame control panels that are intended for use in the control of fossil-fuel burning equipment such as incinerators, kilns and drying ovens. Flame control panels are classified only as to electrical fire and shock hazards incident to their use in ordinary locations. The compatibility of the panel with the controlled equipment from the standpoint of programming the burner(s) and preventing hazardous conditions due to firing of fuel are not determined.

The basic requirement to investigate this category is UL 508A, the Standard of Safety for Industrial Control Panels.

Power Press Control Panels (NITW)

Products Classified under this category include power press control panels which are intended for industrial applications on power-operated machines that perform pressing, punching, shearing or braking operations. Power press control panels are classified only as to fire and electric shock hazards incident to their use in ordinary locations.

Power press control panels are also investigated to determine that they meet the requirements of NFPA, the National Fire Protection Association Electrical Standard for Metal Working Machine Tools, in addition to Article 670 of the National Electrical Code (NEC).

The basic requirement used to investigate this category is UL 508A, the Standard of Safety for Industrial Control Panels.

Industrial control equipment

Auxiliary Devices (NKCR)

Products Listed under this category include the following devices: machine-operated switches, magnetically operated control switches, miscellaneous manually operated switches, push button stations (including parts such as pilot lights and selector switches), thermal and magnetic overload relays, and time delay relays.

The basic standards used to investigate this category are UL 508, the Standard of Safety for Industrial Control Equipment or for overload relays, UL 60947-4-1A, Low-Voltage Switchgear and Controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters.

Because this category contains a variety of devices, the test programs for these devices vary.

For devices similar to pushbuttons and pilot lights, the typical test programs are as follows:

Electromechanical

  • Over and under voltage
  • Temperature and dielectric
  • Overload and endurance

Solid state

  • Breakdown of components
  • Temperature and dielectric
  • Overload and endurance
  • Pullout and secureness
  • Strength of insulating base

For devices similar to overload relays, the typical test programs are as follows:

Mechanical

  • Temperature and dielectric
  • Calibration
  • Overload and endurance
  • Short circuit

Electronic

  • Temperature and dielectric
  • Calibration
  • Breakdown of components
  • Overload and endurance
  • Short circuit

Combination Motor Controllers (NKJH)

Products Listed under this category include combination motor controllers, which provide the motor branch circuit functions of motor controller, disconnect means, short-circuit and ground-fault protection and overload protection. The functions may be provided by individual discrete components or be combined in a single controller unit.

The product is marked "Combination Motor Controller" to signify that all of the motor branch circuit functions indicated above have been evaluated and are included in the Listing of the controller. An open type combination motor controller is intended for factory installation in a switchboard, motor control center, industrial control panel or the like, or for field installation in an enclosure for industrial control equipment, a cabinet or cutout box.

The basic standard used to investigate this category is UL 508, Standard of Safety for Industrial Control Equipment.

Float and Pressure-Operated Switches (NKPZ)

Products Listed under this category include float-operated switches, including weight-operated switches, and pressure-operated switches, including vacuum-operated switches. These devices are for direct control of motors; for use in control circuits of magnetic motor controllers and the like; and for control of other types of loads. Unless otherwise marked, these devices are intended for use only with air, water or other nonhazardous fluids.

The basic standards used to investigate this category are UL 508, the Standard of Safety for Industrial Control Equipment and UL 60947-4-1A, Low-Voltage Switchgear and Controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters.

Magnetic Motor Controllers (NLDX)

Products Listed under this category include the following devices: across-the-line starters; across-the-line starters with motor circuit switches; reduced voltage starters such as autotransformer, part-winding wye-delta, reactance and resistant type; speed regulators; and combined starters and speed regulators. Magnetic switches for controlling other than motor loads are listed under Switches, Industrial Control.

The basic standards used to investigate this category are UL 508, Industrial Control Equipment and UL 60947-4-1A, Low-Voltage Switchgear and Controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters

The typical test program for these devices is as follows:

  • Temperature and dielectric
  • Over and under voltage
  • Overload and endurance
  • Induced potential
  • Pullout and secureness
  • Strength of insulating base
  • Short circuit (for models over 1 hp)

Manual Motor Controllers (NLRV)

Products Listed under this category include the following devices: across-the-line starters; autotransformer starters; reactance type starters; resistance type starters; speed regulators; and combined starters and speed regulators.

The basic standards used to investigate this category are UL 508, the Standard of Safety for Industrial Control Equipment and UL 60947-4-1A, Low-Voltage Switchgear and Controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters.

The typical test program for these devices is as follows:

  • Temperature and dielectric
  • Overload and endurance
  • Pullout and secureness
  • Strength of insulating base
  • Short circuit (for models over 1 hp)

Motor Controllers-Miscellaneous (NMFT)

Products Listed under this category include the following devices: combined manual and magnetic starters; flow operated switches; machine operated switches; proximity operated switches; semi-magnetic starters; solid state reduced voltage starters; and thermal overload switches.

This listing also includes miscellaneous solid-state motor controllers and their accessories which have been reconditioned. Reconditioned miscellaneous solid-state motor controllers and their accessories may also be referred to as rebuilt. Reconditioned miscellaneous solid-state motor controllers and their accessories are factory reconditioned to the extent necessary by disassembly and reassembly using new or reconditioned component parts. The reconditioned miscellaneous solid-state motor controllers and their accessories are subject to the same requirements as new miscellaneous solid-state motor controllers and their accessories. These devices are for direct control of motors. Devices for use in control circuits of motor controllers are listed under Auxiliary Devices.

The basic standard used to investigate this category is UL 508, the Standard of Safety for Industrial Control Equipment.

The typical test program for solid-state starters covered under this category is:

  • Temperature and dielectric
  • Overload and endurance
  • Component breakdown
  • Pullout and secureness
  • Strength of insulating base
  • Short circuit calibration

The typical test program for solid state motor controllers covered under this category is:

  • Temperature and dielectric
  • Overload and endurance
  • Short circuit
  • Component breakdown
  • Pullout and secureness
  • Strength of insulating base

Miscellaneous Apparatus (NMTR)

Products Listed under this category include the following devices: amplifier cards, brakes, circuit monitors, dimmers, autotransformers, clutches, cutout bases for thermal cutouts, resistors, potentiometers, rheostats, power supplies, reactance, resistance, selecting systems, variable-voltage autotransformers, phase converters, enclosed slip rings, indicator interfaces and injection systems.

The basic standard used to investigate this category is UL 508, the Standard of Safety for Industrial Control Equipment.

Switches, Industrial Control (NRNT)

Products Listed under this category include magnetically operated switches, manually operated switches, meter switches, photoelectric switches and solid-state switches. Switches rated in horsepower and with or without pilot duty ratings for use in control circuits are listed under Motor Controllers. Switches are tested to determine their acceptability for continuous operation at their marked rated load.

The basic standards used to investigate this category are UL 508, the Standard of Safety for Industrial Control Equipment and UL 60947-4-1A, Low-Voltage Switchgear and Controlgear - Part 4-1: Contactors and motor-starters - Electromechanical contactors and motor-starters

The typical test programs for these devices are as follows:

Electromechanical

  • Over and under voltage
  • Temperature and dielectric
  • Overload and endurance

Solid state

  • Component breakdown
  • Temperature and dielectric
  • Overload and endurance

Programmable Controllers (NRAQ)

Products Listed under this category include programmable industrial control systems utilizing a programmable memory for internal storage of user-oriented instructions for specific functions such as logic, sequencing, counting, and controlling various industrial equipment through digital or analog inputs or outputs. Other products include power supplies, central processing units, input and output accessories, computer interfaces and programming or program diagnostic units associated with programmable control systems.

Reconditioned or rebuilt programmable controllers and their accessories are also included in this listing. Reconditioned or rebuilt devices are factory reconditioned to the extent that disassembly and reassembly is necessary, using new or reconditioned component parts. The reconditioned devices are subject to the same requirements as new devices.

The basic standards used to investigate this category are UL 508, the Standard of Safety for Industrial Control Equipment and UL Standard for Safety for Programmable Controllers - Part 2: Equipment Requirements and Tests, UL 61131-2.

The typical test program for Programmable Controllers is as follows:

  • Temperature and dielectric
  • Component breakdown
  • Transformer 8 A
  • Overload and endurance
  • Additional enclosure testing as required

Proximity Switches (NRKH)

Products Listed under this category include electronic switching devices that are actuated by position of an object without mechanical contact. These devices respond to inductive, capacitive or photoelectric effects. These devices are for use on industrial machinery or mass production industrial equipment as defined by the Electrical Standard for Industrial Machinery, NFPA 79.

The basic standards used to investigate this category are UL 508, the Standard of Safety for Industrial Control Equipment and UL Standard for Safety for Low-Voltage Switchgear and Controlgear - Part 5-2: Control circuit devices and switching elements - Proximity switches, UL 60947-5-2.

The typical test program for proximity switches is as follows:

  • Temperature and dielectric
  • Overload and endurance
  • Component breakdown
  • Strain relief
  • Aging and flexing (if provided with cable gland)

High voltage industrial control equipment

Motor Controllers, Over 1500 V (NJHU)

Products Listed under this category include enclosed motor controllers having AC voltage ratings in the range of 2.2 kV to 2.5 kV, 3.8 kV to 5.0 kV, or 6.2 kV to 7.2 kV. These devices are intended for starting, stopping, regulating, controlling or protecting electric motors or other electrical loads, including refrigeration equipment.

These devices are investigated for use on three phase circuits having available fault levels not exceeding the MVA rating appearing on the nameplate. The three-phase available symmetrical MVA is equal to the product of the available symmetrical rms short-circuit current, the line-to-line open-circuit voltage, and a phase factor of 1.73 x 10-sup(6).

Motor controllers are intended for across-the-line starting and for making and breaking the circuit when the motor is stalled. Accordingly, they are tested at six times the continuous current rating of the controller at the rated voltage. Some motor controllers are provided with an integrally mounted surge arrester to meet the required impulse withstand.

The basic standard used to investigate this category is UL 347, the Standard of Safety for High Voltage Industrial Control Equipment.

Motor Controller Accessories-Over 1500 V (NJIJ)

Products Listed under this category include accessories for field installation in motor controllers having AC voltage ratings in the range of 2.2 kV to 2.5 kV, 3.8 kV to 5.0 kV or 6.2 kV to 7.2 kV. The motor controllers are intended for starting, stopping, regulating, controlling or protecting electric motors or other electrical loads, including refrigeration equipment.

The basic standard used to investigate this category is UL 347, the Standard of Safety for High Voltage Industrial Control Equipment.

Medium Voltage Power Conversion Equipment (NJIC)

Products Listed under this category include enclosed power-conversion equipment with primary voltage ratings of 1501-7200 V. These devices supply power to control a motor or motors operating at a frequency or voltage different than the input-supply voltage. This category also includes power supply modules, input and output modules, SCR or transistor-output modules, dynamic-braking modules, and input-output accessory kits for medium-voltage power-conversion equipment. This equipment is intended for use in ordinary locations in accordance with the National Electric Code.

The basic standards used to investigate products in this category are ANSI/UL 347, "High Voltage Industrial Control Equipment," and ANSI/UL 508C, "Power Conversion Equipment."

Power conversion equipment

Power Conversion Equipment (NMMS)

Products Listed under this category include equipment that supplies power to control a motor or motors operating at a frequency or voltage different than the input supply voltage. This category also includes power supply modules, input and output modules, SCR or transistor output modules, dynamic braking modules, and input/output accessory kits for power conversion equipment. Power conversion equipment may be either open or enclosed. This equipment is intended for use in ordinary locations in accordance with Article 430 and 440 of the National Electrical Code.

The basic standard used to investigate this category is UL 508C, Power Conversion Equipment.

The typical test program for Drives is as follows:

  • Temperature and dielectric
  • Component breakdown
  • Current limiting
  • Inoperative blower
  • Short circuit
  • Single phasing
  • Solid state motor overload
  • Power supply max A/VA