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Chapter 4 Equipment for General Use | 427.25 | All accessible external surfaces of the pipeline, vessel, or both, being heated shall be physically guarded, isolated, or thermally insulated (with a weatherproof jacket for outside installations) to protect against contact by personnel in the area. [427.25](https://2023.antflix.net#427.25) | https://2023.antflix.net#427.25 |
Chapter 4 Equipment for General Use | 427.26 | A dual-winding transformer with a grounded shield between the primary and secondary windings shall be used to isolate the distribution system from the heating system. [427.26](https://2023.antflix.net#427.26) | https://2023.antflix.net#427.26 |
Chapter 4 Equipment for General Use | 427.27 | The secondary winding of the isolation transformer connected to the pipeline or vessel being heated shall not have an output voltage greater than 30 volts ac. Exception No. 1: In industrial establishments, the isolation transformer connected to the pipeline or vessel being heated shall be permitted to have an output voltage greater than 30 but not more than 80 volts ac to ground where all of the following conditions apply: (1) Conditions of guarding, maintenance, and supervision ensure that only qualified persons have access to the installed systems. (2) Ground-fault protection of equipment is provided. Exception No. 2: In industrial establishments, the isolation transformer connected to the pipeline or vessel being heated shall be permitted to have an output voltage not greater than 132 volts ac to ground where all of the following conditions apply: (1) Conditions of guarding, maintenance, and supervision ensure that only qualified persons service the installed systems. (2) Ground-fault protection of equipment is provided. (3) The pipeline or vessel being heated is completely enclosed in a grounded metal enclosure. (4) The transformer secondary connections to the pipeline or vessel being heated are completely enclosed in a grounded metal mesh or metal enclosure. [427.27](https://2023.antflix.net#427.27) | https://2023.antflix.net#427.27 |
Chapter 4 Equipment for General Use | 427.28 | All current-carrying components shall be installed in accordance with 300.20. [427.28](https://2023.antflix.net#427.28) | https://2023.antflix.net#427.28 |
Chapter 4 Equipment for General Use | 427.29 | The pipeline, vessel, or both, that is being heated and operating at a voltage greater than 30 but not more than 80 shall be grounded at designated points. [427.29](https://2023.antflix.net#427.29) | https://2023.antflix.net#427.29 |
Chapter 4 Equipment for General Use | 427.30 | The ampacity of the conductors connected to the secondary of the transformer shall be at least 100 percent of the total load of the heater. [427.30](https://2023.antflix.net#427.30) | https://2023.antflix.net#427.30 |
Chapter 4 Equipment for General Use | 427.36 | Induction coils that operate or may operate at a voltage greater than 30 volts ac shall be enclosed in a nonmetallic or split metallic enclosure, isolated, or made inaccessible by location to protect personnel in the area. [427.36](https://2023.antflix.net#427.36) | https://2023.antflix.net#427.36 |
Chapter 4 Equipment for General Use | 427.37 | Induction coils shall be prevented from inducing circulating currents in surrounding metallic equipment, supports, or structures by shielding, isolation, or insulation of the current paths. Stray current paths shall be bonded to prevent arcing. [427.37](https://2023.antflix.net#427.37) | https://2023.antflix.net#427.37 |
Chapter 4 Equipment for General Use | 427.45 | The ampacity of the electrically insulated conductor inside the ferromagnetic envelope shall be permitted to exceed the values given in Table 310.16, provided it is identified as suitable for this use. [427.45](https://2023.antflix.net#427.45) | https://2023.antflix.net#427.45 |
Chapter 4 Equipment for General Use | 427.46 | Pull boxes for pulling the electrically insulated conductor in the ferromagnetic envelope shall be permitted to be buried under the thermal insulation, provided their locations are indicated by permanent markings on the insulation jacket surface and on drawings. For outdoor installations, pull boxes shall be of watertight construction. [427.46](https://2023.antflix.net#427.46) | https://2023.antflix.net#427.46 |
Chapter 4 Equipment for General Use | 427.47 | The provisions of 300.20 shall not apply to the installation of a single conductor in a ferromagnetic envelope (metal enclosure). [427.47](https://2023.antflix.net#427.47) | https://2023.antflix.net#427.47 |
Chapter 4 Equipment for General Use | 427.48 | The ferromagnetic envelope shall be grounded at both ends, and, in addition, it shall be permitted to be grounded at intermediate points as required by its design. The ferromagnetic envelope shall be bonded at all joints to ensure electrical continuity. The provisions of 250.30 shall not apply to the installation of skin-effect heating systems. [427.48](https://2023.antflix.net#427.48) | https://2023.antflix.net#427.48 |
Chapter 4 Equipment for General Use | 427.55(A) | Means shall be provided to simultaneously disconnect all fixed electric pipeline or vessel heating equipment from all ungrounded conductors. The branch-circuit switch or circuit breaker, where readily accessible to the user of the equipment, shall be permitted to serve as the disconnecting means. The disconnecting means shall be of the indicating type and shall be capable of being locked in the open (off) position. The disconnecting means shall be installed in accordance with 110.25. [427.55(A)](https://2023.antflix.net#427.55(A)) | https://2023.antflix.net#427.55(A) |
Chapter 4 Equipment for General Use | 427.55(B) | The factory-installed attachment plug of cord-and-plug-connected equipment rated 20 amperes or less and 150 volts or less to ground shall be permitted to be the disconnecting means. [427.55(B)](https://2023.antflix.net#427.55(B)) | https://2023.antflix.net#427.55(B) |
Chapter 4 Equipment for General Use | 427.56(A) | Temperature-controlled switching devices that indicate an "off" position and that interrupt line current shall open all ungrounded conductors when the control device is in this "off" position. These devices shall not be permitted to serve as the disconnecting means unless capable of being locked in the open position. [427.56(A)](https://2023.antflix.net#427.56(A)) | https://2023.antflix.net#427.56(A) |
Chapter 4 Equipment for General Use | 427.56(B) | Temperature controlled switching devices that do not have an "off" position shall not be required to open all ungrounded conductors and shall not be permitted to serve as the disconnecting means. [427.56(B)](https://2023.antflix.net#427.56(B)) | https://2023.antflix.net#427.56(B) |
Chapter 4 Equipment for General Use | 427.56(C) | Remote controlled temperature-actuated devices shall not be required to meet the requirements of 427.56(A) and (B). These devices shall not be permitted to serve as the disconnecting means. [427.56(C)](https://2023.antflix.net#427.56(C)) | https://2023.antflix.net#427.56(C) |
Chapter 4 Equipment for General Use | 427.56(D) | Switching devices consisting of combined temperature-actuated devices and manually controlled switches that serve both as the controllers and the disconnecting means shall comply with all the following conditions: Open all ungrounded conductors when manually placed in the "off" positionBe designed so that the circuit cannot be energized automatically if the device has been manually placed in the "off" positionBe capable of being locked in the open position [427.56(D)](https://2023.antflix.net#427.56(D)) | https://2023.antflix.net#427.56(D) |
Chapter 4 Equipment for General Use | 427.57 | Heating equipment shall be considered protected against overcurrent where supplied by a branch circuit as specified in 210.20 and 210.24. [427.57](https://2023.antflix.net#427.57) | https://2023.antflix.net#427.57 |
Chapter 4 Equipment for General Use | 430.1 | This article covers motors, motor branch-circuit and feeder conductors and their protection, motor overload protection, motor control circuits, motor controllers, and motor control centers.
Informational Note Figure 430.1 Article 430 Contents.
Informational Note No. 1: See Informational Note Figure 430.1 for the arrangement of this article.
Informational Note No. 2: See 110.26(E) for installation requirements for motor control centers.
Informational Note No. 3: See 440.1 for air-conditioning and refrigerating equipment.
Informational Note No. 4: See Part X for additional requirements for motors utilizing adjustable-speed drive systems.
Informational Note No. 5: See Part XI for additional requirements for motors that operate over 1000 volts, nominal. [430.1](https://2023.antflix.net#430.1) | https://2023.antflix.net#430.1 |
Chapter 4 Equipment for General Use | 430.2 | Reconditioned motors shall be permitted if the reconditioning has been conducted in accordance with the manufacturer's instructions or, if no instructions are provided, nationally recognized standards. Reconditioned motors identified for use in hazardous (classified) locations shall be listed as reconditioned if installed in hazardous (classified) locations. Informational Note: See ANSI/EASA AR100-2020, Recommended Practice for the Repair of Rotating Electrical Apparatus, for information on the rewinding and repair of motors. [430.2](https://2023.antflix.net#430.2) | https://2023.antflix.net#430.2 |
Chapter 4 Equipment for General Use | 430.4 | Where separate overload devices are used with a standard part-winding start induction motor, each half of the motor winding shall be individually protected in accordance with 430.32 and 430.37 with a trip current one-half that specified.Each motor-winding connection shall have branch-circuit short-circuit and ground-fault protection rated at not more than one-half that specified by 430.52.
Exception: A short-circuit and ground-fault protective device shall be permitted for both windings if the device will allow the motor to start. Where time-delay (dual-element) fuses are used, they shall be permitted to have a rating not exceeding 150 percent of the motor full-load current. [430.4](https://2023.antflix.net#430.4) | https://2023.antflix.net#430.4 |
Chapter 4 Equipment for General Use | 430.5 | Motors and controllers shall also comply with the applicable provisions of Table 430.5.Table 430.5 Other Articles
Equipment/Occupancy
Article
Section
Air-conditioning and refrigerating equipment
440
Capacitors
460.8, 460.9
Commercial garages; aircraft hangars; motor fuel dispensing facilities; bulk storage plants; spray application, dipping, and coating processes; and inhalation anesthetizing locations
511, 513, 514, 515, 516, and 517 Part IV
Cranes and hoists
610
Electrically driven or controlled irrigation machines
675
Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts
620
Fire pumps
695
Hazardous (classified) locations
500—503, 505, and 506
Industrial machinery
670
Motion picture projectors
540.11 and 540.20
Motion picture and television studios and similar locations
530
Resistors and reactors
470
Theaters, audience areas of motion picture and television studios, and similar locations
520.48
Transformers and transformer vaults
450
[430.5](https://2023.antflix.net#430.5) | https://2023.antflix.net#430.5 |
Chapter 4 Equipment for General Use | 430.6 | The size of conductors supplying equipment covered by this article shall be selected from the ampacity tables in 310.15 or shall be calculated in accordance with 310.14(B). Where flexible cord is used, the size of the conductor shall be selected in accordance with 400.5. The required conductor ampacity and motor ratings shall be determined in accordance with 430.6(A), (B), (C), and (D). [430.6](https://2023.antflix.net#430.6) | https://2023.antflix.net#430.6 |
Chapter 4 Equipment for General Use | 430.6(A) | For general motor applications, current ratings shall be determined based on 430.6(A)(1) and (A)(2). [430.6(A)](https://2023.antflix.net#430.6(A)) | https://2023.antflix.net#430.6(A) |
Chapter 4 Equipment for General Use | 430.6(A)(1) | Other than for motors built for low speeds (less than 1200 RPM) or high torques, and for multispeed motors, the values given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 shall be used instead of the actual current rating marked on the motor nameplate to determine the following: Ampacity of conductorsCurrent ratings of switchesCurrent ratings of branch-circuit short-circuit and ground-fault protectionWhere a motor is marked in amperes, but not horsepower, the horsepower rating shall be assumed to be that corresponding to the value given in Table 430.247, Table 430.248, Table 430.249, and Table 430.250, interpolated if necessary.Exception No. 1: Multispeed motors shall be in accordance with 430.22(B) and 430.52.Exception No. 2: For equipment that employs a shaded-pole or permanent-split capacitor-type fan or blower motor that is marked with the motor type and the marking on the equipment nameplate is not less than the current marked on the fan or blower motor nameplate, the full-load current marked on the nameplate of the appliance shall be used to determine the ampacity of branch-circuit conductors in addition to the current ratings of the following:Disconnecting meansMotor controllersShort-circuit and ground-fault protective devicesSeparate overload protective devicesException No. 3: For a listed motor-operated appliance that is marked with both motor horsepower and full-load current, the motor full-load current marked on the nameplate of the appliance shall be used instead of the horsepower rating on the appliance nameplate to determine the ampacity of branch-circuit conductors in addition to the current ratings of the following:Disconnecting meansMotor controllersShort-circuit and ground-fault protective devicesSeparate overload protective devices [430.6(A)(1)](https://2023.antflix.net#430.6(A)(1)) | https://2023.antflix.net#430.6(A)(1) |
Chapter 4 Equipment for General Use | 430.6(A)(2) | The motor nameplate current ratings shall be used to determine the values for the following: Separate motor overload protectionFor motors built for low speeds (less than 1200 RPM), high torques, canned pumps, or multispeed motors, the following:Ampacity of conductorsCurrent ratings of switchesCurrent ratings of branch-circuit short-circuit and ground-fault protectionLarge motors exceeding the values in Part XIV shall use the nameplate current rating for conductor sizing. [430.6(A)(2)](https://2023.antflix.net#430.6(A)(2)) | https://2023.antflix.net#430.6(A)(2) |
Chapter 4 Equipment for General Use | 430.6(B) | For torque motors, the rated current shall be locked-rotor current, and this nameplate current shall be used to determine the ampacity of the branch-circuit conductors covered in 430.22 and 430.24, the current rating of the motor overload protection, and the current rating of motor branch-circuit short-circuit and ground-fault protection in accordance with 430.52(B). Informational Note: See 430.83(D) and 430.110 for information on motor controllers and disconnecting means. [430.6(B)](https://2023.antflix.net#430.6(B)) | https://2023.antflix.net#430.6(B) |
Chapter 4 Equipment for General Use | 430.6(C) | For motors used in alternating-current, adjustable voltage, variable torque drive systems, the ampacity of conductors, or current ratings of switches, branch-circuit short-circuit and ground-fault protection, and so forth, shall be based on the maximum operating current marked on the motor nameplate or the control nameplate, or both. If the maximum operating current does not appear on the nameplate, the current rating determination shall be based on 150 percent of the values given in Table 430.249 and Table 430.250. [430.6(C)](https://2023.antflix.net#430.6(C)) | https://2023.antflix.net#430.6(C) |
Chapter 4 Equipment for General Use | 430.6(D) | For valve actuator motor assemblies (VAMs), the rated current shall be the name-plate full-load current, and this current shall be used to determine the maximum rating or setting of the motor branch-circuit short-circuit and ground-fault protective device and the ampacity of the conductors. [430.6(D)](https://2023.antflix.net#430.6(D)) | https://2023.antflix.net#430.6(D) |
Chapter 4 Equipment for General Use | 430.7(A) | A motor shall be marked with the following information: Manufacturer's name.Rated volts and full-load current. For a multispeed motor, full-load current for each speed, except shaded-pole and permanent-split capacitor motors where amperes are required only for maximum speed.Rated frequency and number of phases if an ac motor.Rated full-load speed.Rated temperature rise or the insulation system class and rated ambient temperature.Time rating. The time rating shall be 5, 15, 30, or 60 minutes, or continuous.Rated horsepower 1/8 hp or more. For a multispeed motor rated 1/8 hp or more, rated horsepower for each speed, except shaded-pole and permanent-split capacitor motors rated 1/8 hp or more where rated horsepower is required only for maximum speed. Motors of arc welders are not required to be marked with the horsepower rating.Code letter or locked-rotor amperes if an alternating-current motor rated 1/2 hp or more. On polyphase wound-rotor motors, the code letter shall be omitted.Informational Note No. 1: See 430.7(B).Design letter for design A, B, C, or D motors.Informational Note No. 2: See ANSI/NEMA MG 1-2016, Motors and Generators, Part 1, Definitions, for information on motor design letter definition.Secondary volts and full-load current if a wound-rotor induction motor.Field current and voltage for dc excited synchronous motors.Winding - straight shunt, stabilized shunt, compound, or series, if a dc motor. Fractional horsepower dc motors 175 mm (7 in.) or less in diameter shall not be required to be marked.A motor provided with a thermal protector complying with 430.32(A)(2) or (B)(2) shall be marked "thermally protected." Thermally protected motors rated 100 watts or less and complying with 430.32(B)(2) shall be permitted to use the abbreviated marking "T.P."A motor complying with 430.32(B)(4) shall be marked "impedance protected." Impedance-protected motors rated 100 watts or less and complying with 430.32(B)(4) shall be permitted to use the abbreviated marking "Z.P."Motors equipped with electrically powered condensation prevention heaters shall be marked with the rated heater voltage, number of phases, and the rated power in watts.Motors that are electronically protected from overloads in accordance with 430.32(A)(2) and (B)(2) shall be marked "electronically protected" or "E.P." [430.7(A)](https://2023.antflix.net#430.7(A)) | https://2023.antflix.net#430.7(A) |
Chapter 4 Equipment for General Use | 430.7(B) | Code letters marked on motor nameplates to show motor input with locked rotor shall be in accordance with Table 430.7(B). The code letter indicating motor input with locked rotor shall be in an individual block on the nameplate, properly designated.Table 430.7(B) Locked-Rotor Indicating Code Letters
Code Letter
Kilovolt-Amperes per Horsepower with Locked Rotor
A
0—3.14
B
3.15—3.54
C
3.55—3.99
D
4.0—4.49
E
4.5—4.99
F
5.0—5.59
G
5.6—6.29
H
6.3—7.09
J
7.1—7.99
K
8.0—8.99
L
9.0—9.99
M
10.0—11.19
N
11.2—12.49
P
12.5—13.99
R
14.0—15.99
S
16.0—17.99
T
18.0—19.99
U
20.0—22.39
V
22.4 and up
[430.7(B)](https://2023.antflix.net#430.7(B)) | https://2023.antflix.net#430.7(B) |
Chapter 4 Equipment for General Use | 430.7(B)(1) | Multispeed motors shall be marked with the code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) for the highest speed at which the motor can be started. Exception: Constant horsepower multispeed motors shall be marked with the code letter giving the highest locked-rotor kilovolt-ampere (kVA) per horsepower (hp). [430.7(B)(1)](https://2023.antflix.net#430.7(B)(1)) | https://2023.antflix.net#430.7(B)(1) |
Chapter 4 Equipment for General Use | 430.7(B)(2) | Single-speed motors starting on wye connection and running on delta connections shall be marked with a code letter corresponding to the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) for the wye connection. [430.7(B)(2)](https://2023.antflix.net#430.7(B)(2)) | https://2023.antflix.net#430.7(B)(2) |
Chapter 4 Equipment for General Use | 430.7(B)(3) | Dual-voltage motors that have a different locked-rotor kilovolt-ampere (kVA) per horsepower (hp) on the two voltages shall be marked with the code letter for the voltage giving the highest locked-rotor kilovolt-ampere (kVA) per horsepower (hp). [430.7(B)(3)](https://2023.antflix.net#430.7(B)(3)) | https://2023.antflix.net#430.7(B)(3) |
Chapter 4 Equipment for General Use | 430.7(B)(4) | Motors with 50- and 60-Hz ratings shall be marked with a code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) on 60 Hz. [430.7(B)(4)](https://2023.antflix.net#430.7(B)(4)) | https://2023.antflix.net#430.7(B)(4) |
Chapter 4 Equipment for General Use | 430.7(B)(5) | Part-winding start motors shall be marked with a code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) that is based on the locked-rotor current for the full winding of the motor. [430.7(B)(5)](https://2023.antflix.net#430.7(B)(5)) | https://2023.antflix.net#430.7(B)(5) |
Chapter 4 Equipment for General Use | 430.7(C) | Torque motors are rated for operation at standstill and shall be marked in accordance with 430.7(A), except that locked-rotor torque shall replace horsepower. [430.7(C)](https://2023.antflix.net#430.7(C)) | https://2023.antflix.net#430.7(C) |
Chapter 4 Equipment for General Use | 430.7(D)(1) | Multimotor and combination-load equipment shall be provided with a visible nameplate marked with the manufacturer's name, the rating in volts, frequency, number of phases, minimum supply circuit conductor ampacity, and the maximum ampere rating of the circuit short-circuit and ground-fault protective device. The conductor ampacity shall be calculated in accordance with 430.24 and counting all of the motors and other loads that will be operated at the same time. The short-circuit and ground-fault protective device rating shall not exceed the value calculated in accordance with 430.53. Multimotor equipment for use on two or more circuits shall be marked with the preceding information for each circuit. [430.7(D)(1)](https://2023.antflix.net#430.7(D)(1)) | https://2023.antflix.net#430.7(D)(1) |
Chapter 4 Equipment for General Use | 430.7(D)(2) | Where the equipment is not factory-wired and the individual nameplates of motors and other loads are visible after assembly of the equipment, the individual nameplates shall be permitted to serve as the required marking. [430.7(D)(2)](https://2023.antflix.net#430.7(D)(2)) | https://2023.antflix.net#430.7(D)(2) |
Chapter 4 Equipment for General Use | 430.8 | A motor controller shall be marked with the manufacturer's name or identification, the voltage, the current or horsepower rating, the short-circuit current rating, and other necessary data to properly indicate the applications for which it is suitable. Exception No. 1: The short-circuit current rating is not required for motor controllers applied in accordance with 430.81(A) or (B). Exception No. 2: The short-circuit current rating is not required to be marked on the motor controller when the short-circuit current rating of the motor controller is marked elsewhere on the assembly. Exception No. 3: The short-circuit current rating is not required to be marked on the motor controller when the assembly into which it is installed has a marked short-circuit current rating. Exception No. 4: Short-circuit current ratings are not required for motor controllers rated less than 2 hp at 300 V or less and listed exclusively for general-purpose branch circuits. A motor controller that includes motor overload protection suitable for group motor application shall be marked with the motor overload protection and the maximum branch-circuit short-circuit and ground-fault protection for such applications. Combination motor controllers that employ adjustable instantaneous trip circuit breakers shall be clearly marked to indicate the ampere settings of the adjustable trip element. Where a motor controller is built in as an integral part of a motor or of a motor-generator set, individual marking of the motor controller shall not be required if the necessary data are on the nameplate. For motor controllers that are an integral part of equipment approved as a unit, the above marking shall be permitted on the equipment nameplate. Informational Note: See 110.10 for information on circuit impedance and other characteristics. [430.8](https://2023.antflix.net#430.8) | https://2023.antflix.net#430.8 |
Chapter 4 Equipment for General Use | 430.9(A) | Terminals of motors and controllers shall be suitably marked or colored where necessary to indicate the proper connections. [430.9(A)](https://2023.antflix.net#430.9(A)) | https://2023.antflix.net#430.9(A) |
Chapter 4 Equipment for General Use | 430.9(B) | Motor controllers and terminals of control circuit devices shall be connected with copper conductors unless identified for use with a different conductor. [430.9(B)](https://2023.antflix.net#430.9(B)) | https://2023.antflix.net#430.9(B) |
Chapter 4 Equipment for General Use | 430.9(C) | Control circuit devices with screw-type pressure terminals used with 14 AWG or smaller copper conductors shall be torqued to a minimum of 0.8 N-m (7 lb-in.) unless identified for a different torque value. [430.9(C)](https://2023.antflix.net#430.9(C)) | https://2023.antflix.net#430.9(C) |
Chapter 4 Equipment for General Use | 430.10(A) | Enclosures for motor controllers and disconnecting means shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to the other apparatus unless designs are employed that provide adequate space for this purpose. Informational Note: See 312.8 for switch and overcurrent-device enclosures. [430.10(A)](https://2023.antflix.net#430.10(A)) | https://2023.antflix.net#430.10(A) |
Chapter 4 Equipment for General Use | 430.10(B) | Minimum wire-bending space within the enclosures for motor controllers shall be in accordance with Table 430.10(B) where measured in a straight line from the end of the lug or wire connector (in the direction the wire leaves the terminal) to the wall or barrier. Where alternate wire termination means are substituted for that supplied by the manufacturer of the motor controller, they shall be of a type identified by the manufacturer for use with the motor controller and shall not reduce the minimum wire-bending space. Table 430.10(B) Minimum Wire-Bending Space at the Terminals of Enclosed Motor Controllers Size of Wire (AWG or kcmil) Wires per Terminal* 1 2 mm in. mm in. 10 and smaller Not specified - - 8—6 38 11/2 - - 4—3 50 2 - - 2 65 21/2 - - 1 75 3 - - 1/0 125 5 125 5 2/0 150 6 150 6 3/0—4/0 175 7 175 7 250 200 8 200 8 300 250 10 250 10 350—500 300 12 300 12 600—700 350 14 400 16 750—900 450 18 475 19 *Where provision for three or more wires per terminal exists, the minimum wire-bending space shall be in accordance with the requirements of 312.6(B). [430.10(B)](https://2023.antflix.net#430.10(B)) | https://2023.antflix.net#430.10(B) |
Chapter 4 Equipment for General Use | 430.11 | Suitable guards or enclosures shall be provided to protect exposed current-carrying parts of motors and the insulation of motor leads where installed directly under equipment, or in other locations where dripping or spraying oil, water, or other liquid is capable of occurring, unless the motor is designed for the existing conditions. [430.11](https://2023.antflix.net#430.11) | https://2023.antflix.net#430.11 |
Chapter 4 Equipment for General Use | 430.12(A) | Where motors are provided with terminal housings, the housings shall be of metal and of substantial construction. Exception: In other than hazardous (classified) locations, substantial, nonmetallic, noncombustible housings shall be permitted, provided an internal grounding means between the motor frame and the equipment grounding connection is incorporated within the housing. [430.12(A)](https://2023.antflix.net#430.12(A)) | https://2023.antflix.net#430.12(A) |
Chapter 4 Equipment for General Use | 430.12(B) | Where these terminal housings enclose wire-to-wire connections, they shall have minimum dimensions and usable volumes in accordance with Table 430.12(B).
Table 430.12(B) Terminal Housings — Wire-to-Wire Connections
Motors 275 mm (11 in.) in Diameter or Less
Horsepower
Cover Opening Minimum Dimension
Usable Volume Minimum
mm
in.
cm3
in.3
1 and smallera
41
15/8
170
10.5
11/2, 2, and 3b
45
13/4
275
16.8
5 and 71/2
50
2
365
22.4
10 and 15
65
21/2
595
36.4
Motors Over 275 mm (11 in.) in Diameter - Alternating-Current Motors
Maximum Full Load Current for 3-Phase Motors with Maximum of 12 Leads (Amperes)
Terminal Box Cover Opening Minimum Dimension
Usable Volume Minimum
Typical Maximum Horsepower 3-Phase
mm
in.
cm3
in.3
230 Volt
460 Volt
45
65
2.5
595
36.4
15
30
70
84
3.3
1,265
77
25
50
110
100
4.0
2,295
140
40
75
160
125
5.0
4,135
252
60
125
250
150
6.0
7,380
450
100
200
400
175
7.0
13,775
840
150
300
600
200
8.0
25,255
1540
250
500
Direct-Current Motors
Maximum Full-Load Current for Motors with Maximum of 6 Leads (Amperes)
Terminal Box Minimum Dimensions
Usable Volume Minimum
mm
in.
cm3
in.3
68
65
2.5
425
26
105
84
3.3
900
55
165
100
4.0
1,640
100
240
125
5.0
2,950
180
375
150
6.0
5,410
330
600
175
7.0
9,840
600
900
200
8.0
18,040
1,100
Note: Auxiliary leads for such items as brakes, thermostats, space heaters, and exciting fields shall be permitted to be neglected if their current-carrying area does not exceed 25 percent of the current-carrying area of the machine power leads.
aFor motors rated 1 hp and smaller, and with the terminal housing partially or wholly integral with the frame or end shield, the volume of the terminal housing shall not be less than 18.0 cm3 (1.1 in.3) per wire-to-wire connection. The minimum cover opening dimension is not specified.
bFor motors rated 11/2, 2, and 3 hp, and with the terminal housing partially or wholly integral with the frame or end shield, the volume of the terminal housing shall not be less than 23.0 cm3 (1.4 in.3) per wire-to-wire connection. The minimum cover opening dimension is not specified. [430.12(B)](https://2023.antflix.net#430.12(B)) | https://2023.antflix.net#430.12(B) |
Chapter 4 Equipment for General Use | 430.12(C) | Where these terminal housings enclose rigidly mounted motor terminals, the terminal housing shall be of sufficient size to provide minimum terminal spacings and usable volumes in accordance with Table 430.12(C)(1) and Table 430.12(C)(2).Table 430.12(C)(1) Terminal Spacings - Fixed Terminals
Nominal Volts
Minimum Spacing
Between Line Terminals
Between Line Terminals and Other Uninsulated Metal Parts
mm
in.
mm
in.
250 or less
6
1/4
6
1/4
Over 250 — 1000
10
3/8
10
3/8
Table 430.12(C)(2) Usable Volumes - Fixed Terminals
Power-Supply Conductor Size (AWG)
Minimum Usable Volume per Power-Supply Conductor
cm3
in.3
14
16
1
12 and 10
20
11/4
8 and 6
37
21/4
[430.12(C)](https://2023.antflix.net#430.12(C)) | https://2023.antflix.net#430.12(C) |
Chapter 4 Equipment for General Use | 430.12(D) | For motors with larger ratings, greater number of leads, or larger wire sizes, or where motors are installed as a part of factory-wired equipment, without additional connection being required at the motor terminal housing during equipment installation, the terminal housing shall be of ample size to make connections, but the foregoing provisions for the volumes of terminal housings shall not be considered applicable. [430.12(D)](https://2023.antflix.net#430.12(D)) | https://2023.antflix.net#430.12(D) |
Chapter 4 Equipment for General Use | 430.12(E) | A means for attachment of an equipment grounding conductor termination in accordance with 250.8 shall be provided at motor terminal housings for wire-to-wire connections or fixed terminal connections. The means for such connections shall be permitted to be located either inside or outside the motor terminal housing. Exception: Where a motor is installed as a part of factory-wired equipment that is required to be grounded and without additional connection being required at the motor terminal housing during equipment installation, a separate means for motor grounding at the motor terminal housing shall not be required. [430.12(E)](https://2023.antflix.net#430.12(E)) | https://2023.antflix.net#430.12(E) |
Chapter 4 Equipment for General Use | 430.13 | Where wires pass through an opening in an enclosure, conduit box, or barrier, a bushing shall be used to protect the conductors from the edges of openings having sharp edges. The bushing shall have smooth, well-rounded surfaces where it may be in contact with the conductors. If used where oils, greases, or other contaminants may be present, the bushing shall be made of material not deleteriously affected.
Informational Note: See 310.10(F) for conductors exposed to deteriorating agents. [430.13](https://2023.antflix.net#430.13) | https://2023.antflix.net#430.13 |
Chapter 4 Equipment for General Use | 430.14(A) | Motors shall be located so that adequate ventilation is provided and so that maintenance, such as lubrication of bearings and replacing of brushes, can be readily accomplished. Exception: Ventilation shall not be required for submersible types of motors. [430.14(A)](https://2023.antflix.net#430.14(A)) | https://2023.antflix.net#430.14(A) |
Chapter 4 Equipment for General Use | 430.14(B) | Open motors that have commutators or collector rings shall be located or protected so that sparks cannot reach adjacent combustible material. Exception: Installation of these motors on wooden floors or supports shall be permitted. [430.14(B)](https://2023.antflix.net#430.14(B)) | https://2023.antflix.net#430.14(B) |
Chapter 4 Equipment for General Use | 430.16 | In locations where dust or flying material collects on or in motors in such quantities as to seriously interfere with the ventilation or cooling of motors and thereby cause dangerous temperatures, suitable types of enclosed motors that do not overheat under the prevailing conditions shall be used. Informational Note: Especially severe conditions may require the use of enclosed pipe-ventilated motors, or enclosure in separate dusttight rooms, properly ventilated from a source of clean air. [430.16](https://2023.antflix.net#430.16) | https://2023.antflix.net#430.16 |
Chapter 4 Equipment for General Use | 430.17 | In determining compliance with 430.24, 430.53(B), and 430.53(C), the highest rated or smallest rated motor shall be based on the rated full-load current as selected from Table 430.247, Table 430.248, Table 430.249, and Table 430.250. [430.17](https://2023.antflix.net#430.17) | https://2023.antflix.net#430.17 |
Chapter 4 Equipment for General Use | 430.18 | The nominal value of the ac voltage being rectified shall be used to determine the voltage of a rectifier derived system. Exception: The nominal dc voltage of the rectifier shall be used if it exceeds the peak value of the ac voltage being rectified. [430.18](https://2023.antflix.net#430.18) | https://2023.antflix.net#430.18 |
Chapter 4 Equipment for General Use | 430.21 | Part II specifies ampacities of conductors that are capable of carrying the motor current without overheating under the conditions specified.
Part II shall not apply to motor circuits rated over 1000 volts, nominal.
Informational Note No. 1: See Part XI for motor circuits rated over 1000 volts, nominal.
Informational Note No. 2: See 110.14(C) and 430.9(B) for equipment device terminal requirements. [430.21](https://2023.antflix.net#430.21) | https://2023.antflix.net#430.21 |
Chapter 4 Equipment for General Use | 430.22 | Conductors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125 percent of the motor full-load current rating, as determined by 430.6(A)(1), or not less than specified in 430.22(A) through (G). [430.22](https://2023.antflix.net#430.22) | https://2023.antflix.net#430.22 |
Chapter 4 Equipment for General Use | 430.22(A) | For dc motors operating from a rectified power supply, the conductor ampacity on the input of the rectifier shall not be less than 125 percent of the rated input current to the rectifier. For dc motors operating from a rectified single-phase power supply, the conductors between the field wiring output terminals of the rectifier and the motor shall have an ampacity of not less than the following percentages of the motor full-load current rating: Where a rectifier bridge of the single-phase, half-wave type is used, 190 percent.Where a rectifier bridge of the single-phase, full-wave type is used, 150 percent. [430.22(A)](https://2023.antflix.net#430.22(A)) | https://2023.antflix.net#430.22(A) |
Chapter 4 Equipment for General Use | 430.22(B) | For a multispeed motor, the selection of branch-circuit conductors on the line side of the controller shall be based on the highest of the full-load current ratings shown on the motor nameplate. The ampacity of the branch-circuit conductors between the controller and the motor shall not be less than 125 percent of the current rating of the winding(s) that the conductors energize. [430.22(B)](https://2023.antflix.net#430.22(B)) | https://2023.antflix.net#430.22(B) |
Chapter 4 Equipment for General Use | 430.22(C) | For a wye-start, delta-run connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125 percent of the motor full-load current as determined by 430.6(A)(1). The ampacity of the conductors between the controller and the motor shall not be less than 72 percent of the motor full-load current rating as determined by 430.6(A)(1). Informational Note: The individual motor circuit conductors of a wye-start, delta-run connected motor carry 58 percent of the rated load current. The multiplier of 72 percent is obtained by multiplying 58 percent by 1.25. [430.22(C)](https://2023.antflix.net#430.22(C)) | https://2023.antflix.net#430.22(C) |
Chapter 4 Equipment for General Use | 430.22(D) | For a part-winding connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125 percent of the motor full-load current as determined by 430.6(A)(1). The ampacity of the conductors between the controller and the motor shall not be less than 62.5 percent of the motor full-load current rating as determined by 430.6(A)(1). Informational Note: The multiplier of 62.5 percent is obtained by multiplying 50 percent by 1.25. [430.22(D)](https://2023.antflix.net#430.22(D)) | https://2023.antflix.net#430.22(D) |
Chapter 4 Equipment for General Use | 430.22(E) | Conductors for a motor used in a short-time, intermittent, periodic, or varying duty application shall have an ampacity of not less than the percentage of the motor nameplate current rating shown in Table 430.22(E), unless the authority having jurisdiction grants special permission for conductors of lower ampacity. Table 430.22(E) Duty-Cycle Service Classification of Service Nameplate Current Rating Percentages 5-Minute Rated Motor 15-Minute Rated Motor 30- & 60-Minute Rated Motor Continuous Rated Motor Short-time duty operating valves, raising or lowering rolls, etc. 110 120 150 - Intermittent duty freight and passenger elevators, tool heads, pumps, drawbridges, turntables, etc. (for arc welders, see 630.11) 85 85 90 140 Periodic duty rolls, ore- and coal-handling machines, etc. 85 90 95 140 Varying duty 110 120 150 200 Note: Any motor application shall be considered as continuous duty unless the nature of the apparatus it drives is such that the motor will not operate continuously with load under any condition of use. [430.22(E)](https://2023.antflix.net#430.22(E)) | https://2023.antflix.net#430.22(E) |
Chapter 4 Equipment for General Use | 430.22(F) | The conductors between a stationary motor rated 1 hp or less and the separate terminal enclosure permitted in 430.245(B) shall be permitted to be smaller than 14 AWG but not smaller than 18 AWG, provided they have an ampacity as specified in 430.22. [430.22(F)](https://2023.antflix.net#430.22(F)) | https://2023.antflix.net#430.22(F) |
Chapter 4 Equipment for General Use | 430.22(G) | Conductors for small motors shall not be smaller than 14 AWG unless otherwise permitted in 430.22(G)(1) or (G)(2). [430.22(G)](https://2023.antflix.net#430.22(G)) | https://2023.antflix.net#430.22(G) |
Chapter 4 Equipment for General Use | 430.22(G)(1) | 18 AWG individual copper conductors installed in a cabinet or enclosure, copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted, under either of the following sets of conditions: The circuit supplies a motor with a full load current rating, as determined by 430.6(A)(1), of greater than 3.5 amperes, and less than or equal to 5 amperes, and all the following conditions are met:The circuit is protected in accordance with 430.52.The circuit is provided with maximum Class 10 or Class 10A overload protection in accordance with 430.32.Overcurrent protection is provided in accordance with 240.4(D)(1)(2).The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of 3.5 amperes or less, and all the following conditions are met:The circuit is protected in accordance with 430.52.The circuit is provided with maximum Class 20 overload protection in accordance with 430.32.Overcurrent protection is provided in accordance with 240.4(D)(1)(2). [430.22(G)(1)](https://2023.antflix.net#430.22(G)(1)) | https://2023.antflix.net#430.22(G)(1) |
Chapter 4 Equipment for General Use | 430.22(G)(2) | 16 AWG individual copper conductors installed in a cabinet or enclosure, copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted under either of the following sets of conditions: The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of greater than 5.5 amperes, and less than or equal to 8 amperes, and all the following conditions are met:The circuit is protected in accordance with 430.52.The circuit is provided with maximum Class 10 or Class 10A overload protection in accordance with 430.32.Overcurrent protection is provided in accordance with 240.4(D)(2)(2).The circuit supplies a motor with a full-load current rating, as determined by 430.6(A)(1), of 5.5 amperes or less, and all the following conditions are met:The circuit is protected in accordance with 430.52.The circuit is provided with maximum Class 20 overload protection in accordance with 430.32.Overcurrent protection is provided in accordance with 240.4(D)(2)(2). [430.22(G)(2)](https://2023.antflix.net#430.22(G)(2)) | https://2023.antflix.net#430.22(G)(2) |
Chapter 4 Equipment for General Use | 430.23(A) | For continuous duty, the conductors connecting the secondary of a wound-rotor ac motor to its controller shall have an ampacity not less than 125 percent of the full-load secondary current of the motor. [430.23(A)](https://2023.antflix.net#430.23(A)) | https://2023.antflix.net#430.23(A) |
Chapter 4 Equipment for General Use | 430.23(B) | For other than continuous duty, these conductors shall have an ampacity, in percent of full-load secondary current, not less than that specified in Table 430.22(E). [430.23(B)](https://2023.antflix.net#430.23(B)) | https://2023.antflix.net#430.23(B) |
Chapter 4 Equipment for General Use | 430.23(C) | Where the secondary resistor is separate from the controller, the ampacity of the conductors between controller and resistor shall not be less than that shown in Table 430.23(C).
Table 430.23(C) Secondary Conductor
Resistor Duty Classification
Ampacity of Conductor in Percent of Full-Load Secondary Current
Light starting duty
35
Heavy starting duty
45
Extra-heavy starting duty
55
Light intermittent duty
65
Medium intermittent duty
75
Heavy intermittent duty
85
Continuous duty
110
[430.23(C)](https://2023.antflix.net#430.23(C)) | https://2023.antflix.net#430.23(C) |
Chapter 4 Equipment for General Use | 430.24 | Conductors supplying several motors, or a motor(s) and other load(s), shall have an ampacity not less than the sum of each of the following: 125 percent of the full-load current rating of the highest rated motor, as determined by 430.6(A)Sum of the full-load current ratings of all the other motors in the group, as determined by 430.6(A)100 percent of the noncontinuous non-motor load125 percent of the continuous non-motor load.Informational Note: See Informative Annex D, Example No. D8.Exception No. 1: Where one or more of the motors of the group are used for short-time, intermittent, periodic, or varying duty, the ampere rating of such motors to be used in the summation shall be determined in accordance with 430.22(E). For the highest rated motor, the greater of either the ampere rating from 430.22(E) or the largest continuous duty motor full-load current multiplied by 1.25 shall be used in the summation.Exception No. 2: The ampacity of conductors supplying motor-operated fixed electric space-heating equipment shall comply with 424.4(B).Exception No. 3: Where the circuitry is interlocked so as to prevent simultaneous operation of selected motors or other loads, the conductor ampacity shall be permitted to be based on the summation of the currents of the motors and other loads to be operated simultaneously that results in the highest total current. [430.24](https://2023.antflix.net#430.24) | https://2023.antflix.net#430.24 |
Chapter 4 Equipment for General Use | 430.25 | The ampacity of the conductors supplying multimotor and combination-load equipment shall not be less than the minimum circuit ampacity marked on the equipment in accordance with 430.7(D). Where the equipment is not factory-wired and the individual nameplates are visible in accordance with 430.7(D)(2), the conductor ampacity shall be determined in accordance with 430.24. [430.25](https://2023.antflix.net#430.25) | https://2023.antflix.net#430.25 |
Chapter 4 Equipment for General Use | 430.26 | Where reduced heating of the conductors results from motors operating on duty-cycle, intermittently, or from all motors not operating at one time, the authority having jurisdiction may grant permission for feeder conductors to have an ampacity less than specified in 430.24, provided the conductors have sufficient ampacity for the maximum load determined in accordance with the sizes and number of motors supplied and the character of their loads and duties. Informational Note: Demand factors determined in the design of new facilities can often be validated against actual historical experience from similar installations. [430.26](https://2023.antflix.net#430.26) | https://2023.antflix.net#430.26 |
Chapter 4 Equipment for General Use | 430.27 | Where capacitors are installed in motor circuits, conductors shall comply with 460.8 and 460.9. [430.27](https://2023.antflix.net#430.27) | https://2023.antflix.net#430.27 |
Chapter 4 Equipment for General Use | 430.28 | Feeder tap conductors shall have an ampacity not less than that required by Part II, shall terminate in a branch-circuit protective device, and, in addition, shall meet one of the following requirements: Be enclosed either by an enclosed controller or by a race-way, be not more than 3.0 m (10 ft) in length, and, for field installation, be protected by an overcurrent device on the line side of the tap conductor, the rating or setting of which shall not exceed 1000 percent of the tap conductor ampacityHave an ampacity of at least one-third that of the feeder conductors, be suitably protected from physical damage or enclosed in a raceway, and be not more than 7.5 m (25 ft) in lengthHave an ampacity not less than the feeder conductorsException: Feeder taps over 7.5 m (25 ft) long. In high-bay manufacturing buildings [over 11 m (35 ft) high at walls], where conditions of maintenance and supervision ensure that only qualified persons service the systems, conductors tapped to a feeder shall be permitted to be not over 7.5 m (25 ft) long horizontally and not over 30.0 m (100 ft) in total length where all of the following conditions are met:The ampacity of the tap conductors is not less than one-third that of the feeder conductors.The tap conductors terminate with a single circuit breaker or a single set of fuses complying with (1) Part IV, where the load-side conductors are a branch circuit, or (2) Part V, where the load-side conductors are a feeder.The tap conductors are suitably protected from physical damage and are installed in raceways.The tap conductors are continuous from end-to-end and contain no splices.The tap conductors shall be 6 AWG copper or 4 AWG aluminum or larger.The tap conductors shall not penetrate walls, floors, or ceilings.The tap shall not be made, less than 9.0 m (30 ft) from the floor. [430.28](https://2023.antflix.net#430.28) | https://2023.antflix.net#430.28 |
Chapter 4 Equipment for General Use | 430.29 | Conductors connecting the motor controller to separately mounted power accelerating and dynamic braking resistors in the armature circuit shall have an ampacity not less than the value calculated from Table 430.29 using motor full-load current. If an armature shunt resistor is used, the power accelerating resistor conductor ampacity shall be calculated using the total of motor full-load current and armature shunt resistor current. Armature shunt resistor conductors shall have an ampacity of not less than that calculated from Table 430.29 using rated shunt resistor current as full-load current. Table 430.29 Conductor Rating Factors for Power Resistors Time in Seconds Ampacity of Conductor in Percent of Full-Load Current On Off 5 75 35 10 70 45 15 75 55 15 45 65 15 30 75 15 15 85 Continuous Duty 110 [430.29](https://2023.antflix.net#430.29) | https://2023.antflix.net#430.29 |
Chapter 4 Equipment for General Use | 430.31 | Part III specifies overload devices intended to protect motors, motor-control apparatus, and motor branch-circuit conductors against excessive heating due to motor overloads and failure to start. Informational Note No. 1: See Informative Annex D, Example D8. Informational Note No. 2: See Article 100 for the definition of Overload. [430.31](https://2023.antflix.net#430.31) | https://2023.antflix.net#430.31 |
Chapter 4 Equipment for General Use | 430.31(A) | These provisions shall not require overload protection where a power loss would cause a hazard, such as in the case of fire pumps. Informational Note: See 695.7 for protection of fire pump supply conductors. [430.31(A)](https://2023.antflix.net#430.31(A)) | https://2023.antflix.net#430.31(A) |
Chapter 4 Equipment for General Use | 430.31(B) | Part III shall not apply to motor circuits rated over 1000 volts, nominal. Informational Note: See Part XI for over 1000 volts, nominal. [430.31(B)](https://2023.antflix.net#430.31(B)) | https://2023.antflix.net#430.31(B) |
Chapter 4 Equipment for General Use | 430.32(A) | Each motor used in a continuous duty application and rated more than 1 hp shall be protected against overload by one of the means in 430.32(A)(1) through (A)(4). [430.32(A)](https://2023.antflix.net#430.32(A)) | https://2023.antflix.net#430.32(A) |
Chapter 4 Equipment for General Use | 430.32(A)(1) | A separate overload device that is responsive to motor current. This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate full-load current rating: Motors with a marked service factor 1.15 or greater 125% Motors with a marked temperature rise 40°C or less 125% All other motors 115% Modification of this value shall be permitted as provided in 430.32(C). For a multispeed motor, each winding connection shall be considered separately. Where a separate motor overload device is connected so that it does not carry the total current designated on the motor nameplate, such as for wye-delta starting, the proper percentage of nameplate current applying to the selection or setting of the overload device shall be clearly designated on the equipment, or the manufacturer's selection table shall take this into account. Informational Note: See 460.9 for power factor correction capacitors that are installed on the load side of the motor overload device. [430.32(A)(1)](https://2023.antflix.net#430.32(A)(1)) | https://2023.antflix.net#430.32(A)(1) |
Chapter 4 Equipment for General Use | 430.32(A)(2) | A thermal protector integral with the motor shall be approved for use with the motor it protects on the basis that it will prevent dangerous overheating of the motor due to overload and failure to start. An electronically protected motor shall be approved for use on the basis that it will prevent dangerous overheating due to the failure of the electronic control, overload, or failure to start the motor. The ultimate trip current of a thermally or electronically protected motor shall not exceed the following percentage of motor full-load current given in Table 430.248, Table 430.249, and Table 430.250: Motor full-load current 9 amperes or less 170% Motor full-load current from 9.1 to, and including, 20 amperes 156% Motor full-load current greater than 20 amperes 140% If the motor current-interrupting device is separate from the motor and its control circuit is operated by a protective device integral with the motor, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor. [430.32(A)(2)](https://2023.antflix.net#430.32(A)(2)) | https://2023.antflix.net#430.32(A)(2) |
Chapter 4 Equipment for General Use | 430.32(A)(3) | A protective device integral with a motor that will protect the motor against damage due to failure to start shall be permitted if the motor is part of an approved assembly that does not normally subject the motor to overloads. [430.32(A)(3)](https://2023.antflix.net#430.32(A)(3)) | https://2023.antflix.net#430.32(A)(3) |
Chapter 4 Equipment for General Use | 430.32(A)(4) | For motors larger than 1500 hp, a protective device having embedded temperature detectors that cause current to the motor to be interrupted when the motor attains a temperature rise greater than marked on the nameplate in an ambient temperature of 40°C. [430.32(A)(4)](https://2023.antflix.net#430.32(A)(4)) | https://2023.antflix.net#430.32(A)(4) |
Chapter 4 Equipment for General Use | 430.32(B) | Any motor of 1 hp or less that is started automatically shall be protected against overload by one of the following means. [430.32(B)](https://2023.antflix.net#430.32(B)) | https://2023.antflix.net#430.32(B) |
Chapter 4 Equipment for General Use | 430.32(B)(1) | By a separate overload device following the requirements of 430.32(A)(1). For a multispeed motor, each winding connection shall be considered separately. Modification of this value shall be permitted as provided in 430.32(C). [430.32(B)(1)](https://2023.antflix.net#430.32(B)(1)) | https://2023.antflix.net#430.32(B)(1) |
Chapter 4 Equipment for General Use | 430.32(B)(2) | A thermal protector integral with the motor shall be approved for use with the motor that it protects on the basis that it will prevent dangerous overheating of the motor due to overload and failure to start. An electronically protected motor shall be approved for use on the basis that it will prevent dangerous overheating due to the failure of the electronic control, overload, or failure to start the motor. Where the motor current-interrupting device is separate from the motor and its control circuit is operated by a protective device integral with the motor, it shall be arranged so that the opening of the control circuit results in interruption of current to the motor. [430.32(B)(2)](https://2023.antflix.net#430.32(B)(2)) | https://2023.antflix.net#430.32(B)(2) |
Chapter 4 Equipment for General Use | 430.32(B)(3) | A protective device integral with a motor that protects the motor against damage due to failure to start shall be permitted (1) if the motor is part of an approved assembly that does not subject the motor to overloads, or (2) if the assembly is also equipped with other safety controls (such as the safety combustion controls on a domestic oil burner) that protect the motor against damage due to failure to start. Where the assembly has safety controls that protect the motor, it shall be so indicated on the nameplate of the assembly where it will be visible after installation. [430.32(B)(3)](https://2023.antflix.net#430.32(B)(3)) | https://2023.antflix.net#430.32(B)(3) |
Chapter 4 Equipment for General Use | 430.32(B)(4) | If the impedance of the motor windings is sufficient to prevent overheating due to failure to start, the motor shall be permitted to be protected as specified in 430.32(D)(2)a. for manually started motors if the motor is part of an approved assembly in which the motor will limit itself so that it will not be dangerously overheated. Informational Note: Many ac motors of less than 1/20 hp, such as clock motors, series motors, and so forth, and also some larger motors such as torque motors, come within this classification. It does not include split-phase motors having automatic switches that disconnect the starting windings. [430.32(B)(4)](https://2023.antflix.net#430.32(B)(4)) | https://2023.antflix.net#430.32(B)(4) |
Chapter 4 Equipment for General Use | 430.32(C) | Where the sensing element or setting or sizing of the overload device selected in accordance with 430.32(A)(1) and 430.32(B)(1) is not sufficient to start the motor or to carry the load, higher size sensing elements or incremental settings or sizing shall be permitted to be used, provided the trip current of the overload device does not exceed the following percentage of motor nameplate full-load current rating: Motors with marked service factor 1.15 or greater 140% Motors with a marked temperature rise 40°C or less 140% All other motors 130% If not shunted during the starting period of the motor as provided in 430.35, the overload device shall have sufficient time delay to permit the motor to start and accelerate its load. Informational Note: A Class 20 overload relay will provide a longer motor acceleration time than a Class 10 or Class 10A overload relay. A Class 30 overload relay will provide a longer motor acceleration time than a Class 20 overload relay. Use of a higher class overload relay may preclude the need for selection of a higher trip current. [430.32(C)](https://2023.antflix.net#430.32(C)) | https://2023.antflix.net#430.32(C) |
Chapter 4 Equipment for General Use | 430.32(D)(1) | Overload protection shall be in accordance with 430.32(B). [430.32(D)(1)](https://2023.antflix.net#430.32(D)(1)) | https://2023.antflix.net#430.32(D)(1) |
Chapter 4 Equipment for General Use | 430.32(D)(2) | Within Sight from Controller. Overload protection shall be permitted to be furnished by the branch-circuit short-circuit and ground-fault protective device; such device, however, shall not be larger than that specified in Part IV of Article 430.Exception: Any such motor shall be permitted on a nominal 120-volt branch circuit protected at not over 20 amperes.Not Within Sight from Controller. Overload protection shall be in accordance with 430.32(B). [430.32(D)(2)](https://2023.antflix.net#430.32(D)(2)) | https://2023.antflix.net#430.32(D)(2) |
Chapter 4 Equipment for General Use | 430.32(E) | The secondary circuits of wound-rotor ac motors, including conductors, controllers, resistors, and so forth, shall be permitted to be protected against overload by the motor-overload device. [430.32(E)](https://2023.antflix.net#430.32(E)) | https://2023.antflix.net#430.32(E) |
Chapter 4 Equipment for General Use | 430.33 | A motor used for a condition of service that is inherently short-time, intermittent, periodic, or varying duty, as illustrated by Table 430.22(E), shall be permitted to be protected against overload by the branch-circuit short-circuit and ground-fault protective device, provided the protective device rating or setting does not exceed that specified in Table 430.52(C)(1). Any motor application shall be considered to be for continuous duty unless the nature of the apparatus it drives is such that the motor cannot operate continuously with load under any condition of use. [430.33](https://2023.antflix.net#430.33) | https://2023.antflix.net#430.33 |
Chapter 4 Equipment for General Use | 430.35(A) | For a nonautomatically started motor, the overload protection shall be permitted to be shunted or cut out of the circuit during the starting period of the motor if the device by which the overload protection is shunted or cut out cannot be left in the starting position and if fuses or inverse time circuit breakers rated or set at not over 400 percent of the full-load current of the motor are located in the circuit so as to be operative during the starting period of the motor. [430.35(A)](https://2023.antflix.net#430.35(A)) | https://2023.antflix.net#430.35(A) |
Chapter 4 Equipment for General Use | 430.35(B) | The motor overload protection shall not be shunted or cut out during the starting period if the motor is automatically started. Exception: The motor overload protection shall be permitted to be shunted or cut out during the starting period on an automatically started motor where the following apply: (1) The motor starting period exceeds the time delay of available motor overload protective devices, and (2) Listed means are provided to perform the following: a. Sense motor rotation and automatically prevent the shunting or cutout in the event that the motor fails to start, and b. Limit the time of overload protection shunting or cutout to less than the locked rotor time rating of the protected motor, and c. Provide for shutdown and manual restart if motor running condition is not reached. [430.35(B)](https://2023.antflix.net#430.35(B)) | https://2023.antflix.net#430.35(B) |
Chapter 4 Equipment for General Use | 430.36 | Where fuses are used for motor overload protection, a fuse shall be inserted in each ungrounded conductor and also in the grounded conductor if the supply system is 3-wire, 3-phase ac with one conductor grounded. [430.36](https://2023.antflix.net#430.36) | https://2023.antflix.net#430.36 |
Chapter 4 Equipment for General Use | 430.37 | Where devices other than fuses are used for motor overload protection, Table 430.37 shall govern the minimum allowable number and location of overload units such as trip coils or relays. Table 430.37 Overload Units Kind of Motor Supply System Number and Location of Overload Units, Such as Trip Coils or Relays 1-phase ac or dc 2-wire, 1-phase ac or dc ungrounded 1 in either conductor 1-phase ac or dc 2-wire, 1-phase ac or dc, one conductor grounded 1 in ungrounded conductor 1-phase ac or dc 3-wire, 1-phase ac or dc, grounded neutral conductor 1 in either ungrounded conductor 1-phase ac Any 3-phase 1 in ungrounded conductor 2-phase ac 3-wire, 2-phase ac, ungrounded 2, one in each phase 2-phase ac 3-wire, 2-phase ac, one conductor grounded 2 in ungrounded conductors 2-phase ac 4-wire, 2-phase ac, grounded or ungrounded 2, one for each phase in ungrounded conductors 2-phase ac Grounded neutral or 5-wire, 2-phase ac, ungrounded 2, one for each phase in any ungrounded phase wire 3-phase ac Any 3-phase 3, one in each phase* *Exception: An overload unit in each phase shall not be required where overload protection is provided by other approved means. [430.37](https://2023.antflix.net#430.37) | https://2023.antflix.net#430.37 |
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