430.12 Motor Terminal Housings

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.

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.

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

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.

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.