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(A) Material
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.
(B) Dimensions and Space — Wire-to-Wire Connections
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.
(C) Dimensions and Space — Fixed Terminal Connections
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
(D) Large Wire or Factory Connections
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.
(E) Equipment Grounding Connections
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.

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