Chapter 4
NEC & NEMA Standards
1
This section lists excerpts from industry, national, and international standards. The excerpts are for illustration and
educational purposes. There are often several related tables and information for other configurations and applications.
In addition, the standards have added detail and information that applies to all these excerpts. Therefore, any
application should refer to the standard, rather than the excerpts.
Standard
National Electrical Code (NEC)
NFPA 70-2005
National Electrical Safety Code
(NESC) IEEE C2-2002
Motors and Generators (MG1)
NEMA MG1-2003
Organization
National Fire Protection Association,
Batterymarch Park, Quincy, MA
Institute of Electrical & Electronics
Engineers, New York, NewYork
National Electrical Manufacturers
Association
Application
Electrical installations in occupancies
Electrical supply stations, overhead,
and underground lines.
Performance
of
motors
and
generators
2
Electric Power Systems
NEC 240.6(A)
15
125
600
20
150
700
Durham
Standard Ampere Ratings for Fuses & Circuit Breakers
25
175
800
30
200
1000
35
225
1200
40
250
1600
Amperes
45
50
300
350
2000 2500
60
400
3000
70
450
4000
80
500
5000
90
6000
100
-
110
-
Chapter 4
NEC & NEMA Standards
3
Table 310.16 Allowable Ampacities of Insulated Conductors Rated 0 Through 2000 Volts, 60°C
Through 90°C (140°F Through 194°F), Not More Than Three Current-Carrying Conductors in
Raceway, Cable, or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F)
Temperature Rating of Conductor (See Table 310.13.)
60°C
75°C
90°C
60°C
75°C
90°C
(140°F)
(167°F)
(194°F)
(140°F)
(167°F)
(194°F)
Size AWG Types Types RHW, Types TBS, SA, SIS, Types Types RHW, Types TBS, SA,
Size
or kcmil TW, UF THHW, THW, FEP, FEPB, MI, RHH, TW, UF
THHW,
SIS, THHN, THHW, AWG or
THWN,
RHW-2, THHN, THHW,
THW,
THW-2, THWN-2,
kcmil
XHHW, USE,
THW-2, THWN-2,
THWN,
RHH, RHW-2, USEZW
USE-2, XHH, XHHW,
XHHW, USE
2, XHH, XHHW,
XHHW-2, ZW-2
XHHW-2, ZW-2
COPPER
ALUMINUM OR COPPER-CLAD ALUM
18
—
—
14
—
—
—
—
16
—
—
18
—
—
—
—
14*
20
20
25
—
—
—
—
12*
25
25
30
20
20
25
12*
10*
30
35
40
25
30
35
10*
8
40
50
55
30
40
45
8
6
55
65
75
40
50
60
6
4
70
85
95
55
65
75
4
3
85
100
110
65
75
85
3
2
95
115
130
75
90
100
2
1
110
130
150
85
100
115
1
1/0
125
150
170
100
120
135
1/0
2/0
145
175
195
115
135
150
2/0
3/0
165
200
225
130
155
175
3/0
4/0
195
230
260
150
180
205
4/0
250
215
255
290
170
205
230
250
300
240
285
320
190
230
255
300
350
260
310
350
210
250
280
350
400
280
335
380
225
270
305
400
500
320
380
430
260
310
350
500
600
355
420
475
285
340
385
600
700
385
460
520
310
375
420
700
750
400
475
535
320
385
435
750
800
410
490
555
330
395
450
800
900
435
520
585
355
425
480
900
1000
455
545
615
375
445
500
1000
1250
495
590
665
405
485
545
1250
1500
520
625
705
435
520
585
1500
1750
545
650
735
455
545
615
1750
2000
560
665
750
470
560
630
2000
CORRECTION FACTORS
Ambient
For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities
Ambient
Temp.
shown above by the appropriate factor shown below.
Temp.
(°C)
(°F)
21–25
1.08
1.05
1.04
1.08
1.05
1.04
70–77
26–30
1.00
1.00
1.00
1.00
1.00
1.00
78–86
31–35
0.91
0.94
0.96
0.91
0.94
0.96
87–95
36–40
0.82
0.88
0.91
0.82
0.88
0.91
96–104
41–45
0.71
0.82
0.87
0.71
0.82
0.87
105–113
46–50
0.58
0.75
0.82
0.58
0.75
0.82
114–122
51–55
0.41
0.67
0.76
0.41
0.67
0.76
123–131
56–60
—
0.58
0.71
—
0.58
0.71
132–140
61–70
—
0.33
0.58
—
0.33
0.58
141–158
71–80
—
—
0.41
—
—
0.41
159–176
* See 240.4(D).
4
Electric Power Systems
Table 310.15(B)(2)(a) Adjustment
Factors for More Than Three CurrentCarrying Conductors in a Raceway or
Cable
Number of
CurrentCarrying
Conductors
4–6
7–9
10–20
21–30
31–40
41 and above
Percent of Values in Tables
310.16 through 310.19 as
Adjusted for Ambient
Temperature if Necessary
80
70
50
45
40
35
Durham
Table 310.15(B)(6) Conductor Types and Sizes
for 120/240-Volt, 3-Wire, Single-Phase Dwelling
Services and Feeders.
Conductor Types RHH, RHW, RHW-2, THHN,
THHW, THW, THW-2, THWN, THWN-2, XHHW,
XHHW-2, SE, USE, USE-2
Conductor (AWG or kcmil)
Copper
Aluminum or
Copper-Clad
Aluminum
4
2
3
1
2
1/0
1
2/0
1/0
3/0
2/0
4/0
3/0
250
4/0
300
250
350
350
500
400
600
Service or
Feeder Rating
(Amperes)
100
110
125
150
175
200
225
250
300
350
400
Chapter 4
NEC & NEMA Standards
Figure 430.1
Article 430 Contents
5
6
Electric Power Systems
Table 430.7(B)
Code
Letter
A
B
C
D
E
F
G
H
J
K
Locked-Rotor Indicating Code Letters
Kilovolt-Amperes
per Horsepower
with Locked Rotor
0–3.14
3.15–3.54
3.55–3.99
4.0–4.49
4.5–4.99
5.0–5.59
5.6–6.29
6.3–7.09
7.1–7.99
8.0–8.99
Code
Letter
L
M
N
P
R
S
T
U
V
Kilovolt-Amperes
per Horsepower
with Locked Rotor
9.0–9.99
10.0–11.19
11.2–12.49
12.5–13.99
14.0–15.99
16.0–17.99
18.0–19.99
20.0–22.39
22.4 and up
Table 430.52 Maximum Rating or Setting of Motor Branch-Circuit ShortCircuit and Ground-Fault Protective Devices
Percentage of Full-Load Current
Dual Element Instantaneous Inverse Time
(Time-Delay)
Trip Breaker
Breaker
Fuse
Single-phase motors
300
175
800
250
AC polyphase motors other than wound-rotor
Squirrel cage
300
175
800
250
other than Design B
energy-efficient
Design B
300
175
1100
250
energy-efficient
Synchronous
300
175
800
250
Wound rotor
150
150
800
150
Direct current
150
150
250
150
(constant voltage)
Type of Motor
Non-time
Delay Fuse
Durham
Chapter 4
Table 430.91
NEC & NEMA Standards
7
Motor Controller Enclosure Selection
Provides a Degree of
Protection Against the
Following
Environmental
Conditions
Incidental contact with the
enclosed equipment
Rain, snow, and sleet
Sleet2
Windblown dust
Hosedown
Corrosive agents
Temporary submersion
Prolonged submersion
3
For Outdoor Use
Enclosure Type Number1
3R
3S
3X 3RX 3SX
4
4X
6
6P
X
X
X
X
X
X
X
X
X
X
X
—
X
—
—
—
—
X
—
—
—
—
—
—
X
X
X
—
—
—
—
X
—
X
—
X
—
—
X
—
—
—
X
—
—
X
X
X
—
X
—
—
X
—
X
X
—
—
—
X
—
X
X
X
—
—
X
—
X
X
—
X
—
X
—
X
X
X
X
X
For Indoor Use
Enclosure Type Number1
2
4
4X
5
6
6P
12
Provides a Degree of
1
12K 13
Protection Against the
Following
Environmental
Conditions
Incidental contact with the
X
X
X
X
X
X
X
X
X
X
enclosed equipment
Falling dirt
X
X
X
X
X
X
X
X
X
X
Falling liquids and light
—
X
X
X
X
X
X
X
X
X
splashing
Circulating dust, lint,
—
—
X
X
—
X
X
X
X
X
fibers, and flyings
Settling airborne dust, lint, —
—
X
X
X
X
X
X
X
X
fibers, and flyings
Hosedown and splashing
—
—
X
X
—
X
X
—
—
—
water
Oil and coolant seepage
—
—
—
—
—
—
—
X
X
X
Oil or coolant spraying
—
—
—
—
—
—
—
—
—
X
and splashing
Corrosive agents
—
—
—
X
—
—
X
—
—
—
Temporary submersion
—
—
—
—
—
X
X
—
—
—
Prolonged submersion
—
—
—
—
—
—
X
—
—
—
1Enclosure type number shall be marked on the motor controller enclosure.
2Mechanism shall be operable when ice covered.
FPN: The term raintight is typically used in conjunction with Enclosure Types 3, 3S, 3SX,
3X, 4, 4X, 6, 6P. The term rainproof is typically used in conjunction with Enclosure Type 3R,
3RX. The term watertight is typically used in conjunction with Enclosure Types 4, 4X, 6, 6P.
The term driptight is typically used in conjunction with Enclosure Types 2, 5, 12, 12K, 13.
The term dusttight is typically used in conjunction with Enclosure Types 3, 3S, 3SX, 3X, 5,
12, 12K, 13.
8
Electric Power Systems
Table 430.248 Full-Load
Currents in Amperes, SinglePhase Alternating-Current
Motors
Horsepower
¼
½
¾
1
1½
2
3
5
7½
10
115
Volts
4.4
5.8
7.2
9.8
13.8
16
20
24
34
56
80
100
Table 430.250
200
Volts
2.5
3.3
4.1
5.6
7.9
9.2
11.5
13.8
19.6
32.2
46.0
57.5
208
Volts
2.4
3.2
4.0
5.4
7.6
8.8
11.0
13.2
18.7
30.8
44.0
55.0
230
Volts
2.2
2.9
3.6
4.9
6.9
8.0
10
12
17
28
40
50
Full-Load Current, Three-Phase Alternating-Current Motors
Induction-Type Squirrel Cage and Wound Rotor
Synchronous-Type
(Amperes)
Unity Power Factor* (Amperes)
Horse- 115
200
208
230
460 575 Volts 2300
230
460
575
2300
power Volts Volts Volts Volts Volts
Volts
Volts Volts Volts Volts
½
4.4
2.5
2.4
2.2
1.1
0.9
—
—
—
—
—
¾
6.4
3.7
3.5
3.2
1.6
1.3
—
—
—
—
—
1
8.4
4.8
4.6
4.2
2.1
1.7
—
—
—
—
—
1½
12.0
6.9
6.6
6.0
3.0
2.4
—
—
—
—
—
2
13.6
7.8
7.5
6.8
3.4
2.7
—
—
—
—
—
3
—
11.0
10.6
9.6
4.8
3.9
—
—
—
—
—
5
—
17.5
16.7
15.2
7.6
6.1
—
—
—
—
—
7½
—
25.3
24.2
22
11
9
—
—
—
—
—
10
—
32.2
30.8
28
14
11
—
—
—
—
—
15
—
48.3
46.2
42
21
17
—
—
—
—
—
20
—
62.1
59.4
54
27
22
—
—
—
—
—
25
—
78.2
74.8
68
34
27
—
53
26
21
—
30
—
92
88
80
40
32
—
63
32
26
—
40
—
120
114
104
52
41
—
83
41
33
—
50
—
150
143
130
65
52
—
104
52
42
—
60
—
177
169
154
77
62
16
123
61
49
12
75
—
221
211
192
96
77
20
155
78
62
15
100
—
285
273
248
124
99
26
202
101
81
20
125
—
359
343
312
156
125
31
253
126
101
25
150
—
414
396
360
180
144
37
302
151
121
30
200
552
528
480
240
192
49
400
201
161
40
250
—
—
—
—
302
242
60
—
—
—
—
300
—
—
—
—
361
289
72
—
—
—
—
350
—
—
—
—
414
336
83
—
—
—
—
400
—
—
—
—
477
382
95
—
—
—
—
450
—
—
—
—
515
412
103
—
—
—
—
500
—
—
—
—
590
472
118
—
—
—
—
*For 90 and 80 percent power factor, the figures shall be multiplied by 1.1 and 1.25, respectively.
Durham
Chapter 4
NEC & NEMA Standards
Table 430.251(A) Conversion Table of Single-Phase
Locked- Rotor Currents for Selection of
Disconnecting Means and Controllers as Determined
from Horsepower and Voltage Rating
Rated
Horsepower
½
¾
1
1½
2
3
5
7½
10
Maximum Locked-Rotor Current in Amperes,
Single Phase
115 Volts
208 Volts
230 Volts
58.8
32.5
29.4
82.8
45.8
41.4
96
53
48
120
66
60
144
80
72
204
113
102
336
186
168
480
265
240
600
332
300
Table 430.251(B) Conversion Table of Polyphase Design B, C, and D Maximum Locked-Rotor
Currents for Selection of Disconnecting Means and Controllers as Determined from
Horsepower and Voltage Rating and Design Letter
Rated
Horsepower
Maximum Motor Locked-Rotor Current in Amperes, Two- and Three-Phase, Design B, C, and D*
115 Volts
200 Volts
208 Volts
230 Volts
460 Volts
575 Volts
B, C, D
B, C, D
B, C, D
B, C, D
B, C, D
B, C, D
½
40
23
22.1
20
10
8
¾
50
28.8
27.6
25
12.5
10
1
60
34.5
33
30
15
12
1½
80
46
44
40
20
16
2
100
57.5
55
50
25
20
3
—
73.6
71
64
32
25.6
5
—
105.8
102
92
46
36.8
7½
—
146
140
127
63.5
50.8
10
—
186.3
179
162
81
64.8
15
—
267
257
232
116
93
20
—
334
321
290
145
116
25
—
420
404
365
183
146
30
—
500
481
435
218
174
40
—
667
641
580
290
232
50
—
834
802
725
363
290
60
—
1001
962
870
435
348
75
—
1248
1200
1085
543
434
100
—
1668
1603
1450
725
580
125
—
2087
2007
1815
908
726
150
—
2496
2400
2170
1085
868
200
—
3335
3207
2900
1450
1160
250
—
—
—
—
1825
1460
300
—
—
—
—
2200
1760
350
—
—
—
—
2550
2040
400
—
—
—
—
2900
2320
450
—
—
—
—
3250
2600
500
—
—
—
—
3625
2900
*Design A motors are not limited to a maximum starting current or locked rotor current.
These tables for use only with 430.110, 440.12, 440.41 and 455.8(C).
9
10
Table 8
Electric Power Systems
Durham
Conductor Properties
Conductors
Direct-Current Resistance at 75°C (167°F)
Size
Stranding
Overall
Copper
Aluminum
(AWG
Area
Quantity Diameter
Diameter
Area
Uncoated
Coated
or
mm2 Circular
mm in.
mm
in. mm2 in.2
ohm/
ohm/
ohm/
ohm/
ohm/ ohm/
kcmil)
mils
km
kFT
km
kFT
km
kFT
18
0.823 1620
1
—
—
1.02 0.040 0.823 0.001 25.5
7.77
26.5
8.08
42.0
12.8
18
0.823 1620
7
0.39 0.015 1.16 0.046 1.06 0.002 26.1
7.95
27.7
8.45
42.8
13.1
16
1.31
2580
1
—
—
1.29 0.051 1.31 0.002 16.0
4.89
16.7
5.08
26.4
8.05
16
1.31
2580
7
0.49 0.019 1.46 0.058 1.68 0.003 16.4
4.99
17.3
5.29
26.9
8.21
14
2.08
4110
1
—
—
1.63 0.064 2.08 0.003 10.1
3.07
10.4
3.19
16.6
5.06
14
2.08
4110
7
0.62 0.024 1.85 0.073 2.68 0.004 10.3
3.14
10.7
3.26
16.9
5.17
12
3.31
6530
1
—
—
2.05 0.081 3.31 0.005 6.34
1.93
6.57
2.01
10.45
3.18
12
3.31
6530
7
0.78 0.030 2.32 0.092 4.25 0.006 6.50
1.98
6.73
2.05
10.69
3.25
10
5.261 10380
1
—
— 2.588 0.102 5.26 0.008 3.984
1.21
4.148
1.26
6.561
2.00
10
5.261 10380
7
0.98 0.038 2.95 0.116 6.76 0.011 4.070
1.24
4.226
1.29
6.679
2.04
8
8.367 16510
1
—
— 3.264 0.128 8.37 0.013 2.506
0.764
2.579
0.786
4.125
1.26
8
8.367 16510
7
1.23 0.049 3.71 0.146 10.76 0.017 2.551
0.778
2.653
0.809
4.204
1.28
6
13.30 26240
7
1.56 0.061 4.67 0.184 17.09 0.027 1.608
0.491
1.671
0.510
2.652 0.808
4
21.15 41740
7
1.96 0.077 5.89 0.232 27.19 0.042 1.010
0.308
1.053
0.321
1.666 0.508
3
26.67 52620
7
2.20 0.087 6.60 0.260 34.28 0.053 0.802
0.245
0.833
0.254
1.320 0.403
2
33.62 66360
7
2.47 0.097 7.42 0.292 43.23 0.067 0.634
0.194
0.661
0.201
1.045 0.319
1
42.41 83690
19
1.69 0.066 8.43 0.332 55.80 0.087 0.505
0.154
0.524
0.160
0.829 0.253
1/0 53.49 105600
19
1.89 0.074 9.45 0.372 70.41 0.109 0.399
0.122
0.415
0.127
0.660 0.201
2/0 67.43 133100
19
2.13 0.084 10.62 0.418 88.74 0.137 0.3170 0.0967 0.329
0.101
0.523 0.159
3/0 85.01 167800
19
2.39 0.094 11.94 0.470 111.9 0.173 0.2512 0.0766 0.2610 0.0797 0.413 0.126
4/0 107.2 211600
19
2.68 0.106 13.41 0.528 141.1 0.219 0.1996 0.0608 0.2050 0.0626 0.328 0.100
250
127
—
37
2.09 0.082 14.61 0.575 168 0.260 0.1687 0.0515 0.1753 0.0535 0.2778 0.0847
300
152
—
37
2.29 0.090 16.00 0.630 201 0.312 0.1409 0.0429 0.1463 0.0446 0.2318 0.0707
350
177
—
37
2.47 0.097 17.30 0.681 235 0.364 0.1205 0.0367 0.1252 0.0382 0.1984 0.0605
400
203
—
37
2.64 0.104 18.49 0.728 268 0.416 0.1053 0.0321 0.1084 0.0331 0.1737 0.0529
500
253
—
37
2.95 0.116 20.65 0.813 336 0.519 0.0845 0.0258 0.0869 0.0265 0.1391 0.0424
600
304
—
61
2.52 0.099 22.68 0.893 404 0.626 0.0704 0.0214 0.0732 0.0223 0.1159 0.0353
700
355
—
61
2.72 0.107 24.49 0.964 471 0.730 0.0603 0.0184 0.0622 0.0189 0.0994 0.0303
750
380
—
61
2.82 0.111 25.35 0.998 505 0.782 0.0563 0.0171 0.0579 0.0176 0.0927 0.0282
800
405
—
61
2.91 0.114 26.16 1.030 538 0.834 0.0528 0.0161 0.0544 0.0166 0.0868 0.0265
900
456
—
61
3.09 0.122 27.79 1.094 606 0.940 0.0470 0.0143 0.0481 0.0147 0.0770 0.0235
1000 507
—
61
3.25 0.128 29.26 1.152 673 1.042 0.0423 0.0129 0.0434 0.0132 0.0695 0.0212
1250 633
—
91
2.98 0.117 32.74 1.289 842 1.305 0.0338 0.0103 0.0347 0.0106 0.0554 0.0169
1500 760
—
91
3.26 0.128 35.86 1.412 1011 1.566 0.02814 0.00858 0.02814 0.00883 0.0464 0.0141
1750 887
—
127
2.98 0.117 38.76 1.526 1180 1.829 0.02410 0.00735 0.02410 0.00756 0.0397 0.0121
2000 1013
—
127
3.19 0.126 41.45 1.632 1349 2.092 0.02109 0.00643 0.02109 0.00662 0.0348 0.0106
Notes:
1. These resistance values are valid only for the parameters as given. Using conductors having coated strands, different stranding
type, and, especially, other temperatures changes the resistance.
2. Formula for temperature change: R2 = R1 [1 + α (T 2 - 75)] where α cu = 0.00323, α AL = 0.00330 at 75°C.
3. Conductors with compact and compressed stranding have about 9 percent and 3 percent, respectively, smaller bare conductor
diameters than those shown. See Table 5A for actual compact cable dimensions.
4. The IACS conductivities used: bare copper = 100%, aluminum = 61%.
5. Class B stranding is listed as well as solid for some sizes. Its overall diameter and area is that of its circumscribing circle.
Chapter 4
NEC & NEMA Standards
11
Table 9 Alternating-Current Resistance and Reactance for 600-Volt Cables, 3-Phase, 60 Hz, 75°C
(167°F) — Three Single Conductors in Conduit
Ohms to Neutral per Kilometer
Ohms to Neutral per 1000 Feet6
XL
Alternating-Current
Alternating-Current
Effective Z
Effective Z
(Reactance) for
Resistance for
Resistance for
at 0.85 PF for
at 0.85 PF for
Size
All Wires
Uncoated Copper Wires
Aluminum Wires
Uncoated Copper Wires
Aluminum Wires
Size
(AWG
PVC,
Steel
PVC Aluminum Steel
PVC Aluminum Steel
PVC Aluminum Steel
PVC Aluminum Steel (AWG
or Aluminum Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit Conduit or
kcmil) Conduits
kcmil)
14
0.190
0.240
10.2
10.2
10.2
—
—
—
8.9
8.9
8.9
—
—
—
14
0.058
0.073
3.1
3.1
3.1
—
—
—
2.7
2.7
2.7
—
—
—
12
0.177
0.223
6.6
6.6
6.6
10.5
10.5
10.5
5.6
5.6
5.6
9.2
9.2
9.2
12
0.054
0.068
2.0
2.0
2.0
3.2
3.2
3.2
1.7
1.7
1.7
2.8
2.8
2.8
10
0.164
0.207
3.9
3.9
3.9
6.6
6.6
6.6
3.6
3.6
3.6
5.9
5.9
5.9
10
0.050
0.063
1.2
1.2
1.2
2.0
2.0
2.0
1.1
1.1
1.1
1.8
1.8
1.8
8
0.171
0.213
2.56
2.56
2.56
4.3
4.3
4.3
2.26
2.26
2.30
3.6
3.6
3.6
8
0.052
0.065
0.78
0.78
0.78
1.3
1.3
1.3
0.69
0.69
0.70
1.1
1.1
1.1
6
0.167
0.210
1.61
1.61
1.61
2.66
2.66
2.66
1.44
1.48
1.48
2.33
2.36
2.36
6
0.051
0.064
0.49
0.49
0.49
0.81
0.81
0.81
0.44
0.45
0.45
0.71
0.72
0.72
4
0.157
0.197
1.02
1.02
1.02
1.67
1.67
1.67
0.95
0.95
0.98
1.51
1.51
1.51
4
0.048
0.060
0.31
0.31
0.31
0.51
0.51
0.51
0.29
0.29
0.30
0.46
0.46
0.46
3
0.154
0.194
0.82
0.82
0.82
1.31
1.35
1.31
0.75
0.79
0.79
1.21
1.21
1.21
3
0.047
0.059
0.25
0.25
0.25
0.40
0.41
0.40
0.23
0.24
0.24
0.37
0.37
0.37
2
0.148
0.187
0.62
0.66
0.66
1.05
1.05
1.05
0.62
0.62
0.66
0.98
0.98
0.98
2
0.045
0.057
0.19
0.20
0.20
0.32
0.32
0.32
0.19
0.19
0.20
0.30
0.30
0.30
1
0.151
0.187
0.49
0.52
0.52
0.82
0.85
0.82
0.52
0.52
0.52
0.79
0.79
0.82
1
0.046
0.057
0.15
0.16
0.16
0.25
0.26
0.25
0.16
0.16
0.16
0.24
0.24
0.25
1/0
0.144
0.180
0.39
0.43
0.39
0.66
0.69
0.66
0.43
0.43
0.43
0.62
0.66
0.66
1/0
0.044
0.055
0.12
0.13
0.12
0.20
0.21
0.20
0.13
0.13
0.13
0.19
0.20
0.20
2/0
0.141
0.177
0.33
0.33
0.33
0.52
0.52
0.52
0.36
0.36
0.36
0.52
0.52
0.52
2/0
0.043
0.054
0.10
0.10
0.10
0.16
0.16
0.16
0.11
0.11
0.11
0.16
0.16
0.16
3/0
0.138
0.171 0.253
0.269
0.259
0.43
0.43
0.43
0.289
0.302
0.308
0.43
0.43
0.46
3/0
0.042
0.052
0.077 0.082
0.079
0.13
0.13
0.13
0.088 0.092
0.094
0.13
0.13
0.14
4/0
0.135
0.167 0.203
0.220
0.207
0.33
0.36
0.33
0.243
0.256
0.262
0.36
0.36
0.36
4/0
0.041
0.051
0.062 0.067
0.063
0.10
0.11
0.10
0.074 0.078
0.080
0.11
0.11
0.11
250
0.135
0.171 0.171
0.187
0.177 0.279
0.295
0.282 0.217
0.230
0.240 0.308
0.322
0.33
250
0.041
0.052
0.052 0.057
0.054
0.085 0.090
0.086
0.066 0.070
0.073
0.094 0.098
0.10
300
0.135
0.167 0.144
0.161
0.148 0.233
0.249
0.236 0.194
0.207
0.213 0.269
0.282
0.289 300
0.041
0.051
0.044 0.049
0.045
0.071 0.076
0.072
0.059 0.063
0.065
0.082 0.086
0.088
350
0.131
0.164 0.125
0.141
0.128 0.200
0.217
0.207 0.174
0.190
0.197 0.240
0.253
0.262 350
0.040
0.050
0.038 0.043
0.039
0.061 0.066
0.063
0.053 0.058
0.060
0.073 0.077
0.080
400
0.131
0.161 0.108
0.125
0.115 0.177
0.194
0.180 0.161
0.174
0.184 0.217
0.233
0.240 400
0.040
0.049
0.033 0.038
0.035
0.054 0.059
0.055
0.049 0.053
0.056
0.066 0.071
0.073
500
0.128
0.157 0.089
0.105
0.095 0.141
0.157
0.148 0.141
0.157
0.164 0.187
0.200
0.210 500
0.039
0.048
0.027 0.032
0.029
0.043 0.048
0.045
0.043 0.048
0.050
0.057 0.061
0.064
600
0.128
0.157 0.075
0.092
0.082 0.118
0.135
0.125 0.131
0.144
0.154 0.167
0.180
0.190 600
0.039
0.048
0.023 0.028
0.025
0.036 0.041
0.038
0.040 0.044
0.047
0.051 0.055
0.058
750
0.125
0.157 0.062
0.079
0.069 0.095
0.112
0.102 0.118
0.131
0.141 0.148
0.161
0.171 750
0.038
0.048
0.019 0.024
0.021
0.029 0.034
0.031
0.036 0.040
0.043
0.045 0.049
0.052
1000
0.121
0.151 0.049
0.062
0.059 0.075
0.089
0.082 0.105
0.118
0.131 0.128
0.138
0.151 1000
0.037
0.046
0.015 0.019
0.018
0.023 0.027
0.025
0.032 0.036
0.040
0.039 0.042
0.046
Notes:
1. These values are based on the following constants: UL-Type RHH wires with Class B stranding, in cradled
configuration. Wire conductivities are 100 percent IACS copper and 61 percent IACS aluminum, and aluminum conduit is
45 percent IACS. Capacitive reactance is ignored, since it is negligible at these voltages. These resistance values are
valid only at 75°C (167°F) and for the parameters as given, but are representative for 600-volt wire types operating at 60
Hz.
2. Effective Z is defined as R cos(θ) + X sin(θ), where θ is the power factor angle of the circuit. Multiplying current by
effective impedance gives a good approximation for line-to-neutral voltage drop. Effective impedance values shown in
this table are valid only at 0.85 power factor. For another circuit power factor (PF), effective impedance (Ze) can be
calculated from R and XL values given in this table as follows: Ze = R × PF + XL sin[arccos(PF)].
12
Electric Power Systems
Durham
Table C.4 Maximum Number of Conductors or Fixture Wires in Intermediate Metal Conduit
(IMC) (Based on Table 1, Chapter 9)
Type
RHH, RHW,
RHW-2
TW
RHH*, RHW*,
RHW-2*,
THHW, THW,
THW-2
Size
(AWG/
kcmil)
14
12
10
8
6
4
3
2
1
1/0
2/0
3/0
4/0
250
300
350
400
500
600
700
750
800
900
1000
1250
1500
1750
2000
14
12
10
8
14
12
10
8
6
4
3
2
1
1/0
2/0
3/0
4/0
250
300
350
400
500
600
700
750
16
(½)
4
4
3
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
10
7
5
3
6
5
4
2
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
21
(¾)
8
6
5
3
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
17
13
9
5
11
9
7
4
3
2
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
27
(1)
13
11
8
4
3
3
2
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
27
21
15
8
18
14
11
7
5
4
3
3
1
1
1
1
1
1
1
1
0
0
0
0
0
CONDUCTORS
Metric Designator (Trade Size)
35
41
53
63
(1¼)
(1½)
(2)
(2½)
22
30
49
70
18
25
41
58
15
20
33
47
8
10
17
24
6
8
14
19
5
6
11
15
4
6
9
13
3
5
8
11
2
3
5
7
1
3
4
6
1
2
4
6
1
1
3
5
1
1
3
4
1
1
1
3
1
1
1
3
1
1
1
2
1
1
1
2
1
1
1
1
0
1
1
1
0
1
1
1
0
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
0
1
0
0
0
1
0
0
0
1
47
64
104
147
36
49
80
113
27
36
59
84
15
20
33
47
31
42
69
98
25
34
56
79
19
26
43
61
12
16
26
37
9
12
20
28
6
9
15
21
6
8
13
18
5
6
11
15
3
4
7
11
3
4
6
9
2
3
5
8
1
3
4
6
1
2
4
5
1
1
3
4
1
1
2
4
1
1
2
3
1
1
1
3
1
1
1
2
1
1
1
1
0
1
1
1
0
1
1
1
78
(3)
108
89
72
38
30
23
21
18
12
10
9
7
6
5
4
4
3
3
2
2
1
1
1
1
1
1
1
1
228
175
130
72
151
122
95
57
43
32
28
23
16
14
12
10
8
7
6
5
4
4
3
3
2
91
(3½)
144
120
97
50
40
31
28
24
16
14
12
10
9
6
6
5
5
4
3
3
3
3
2
2
1
1
1
1
304
234
174
97
202
163
127
76
58
43
37
31
22
19
16
13
11
9
8
7
6
5
4
4
3
103
(4)
186
154
124
65
52
41
36
31
20
18
15
13
11
8
7
7
6
5
4
4
4
3
3
3
2
1
1
1
392
301
224
124
261
209
163
98
75
56
48
41
28
24
20
17
14
12
10
9
8
7
5
5
4
Chapter 4
THHN, THWN,
THWN-2
FEP, FEPB,
PFA, PFAH,
TFE
PFA, PFAH,
TFE
Z
XHH, XHHW,
XHHW-2, ZW
NEC & NEMA Standards
800
900
1000
1250
1500
1750
2000
14
12
10
8
6
4
3
2
1
1/0
2/0
3/0
4/0
250
300
350
400
500
600
700
750
800
900
1000
14
12
10
8
6
4
3
2
1
1/0
2/0
3/0
4/0
14
12
10
8
6
4
3
2
1
14
12
10
8
6
4
3
0
0
0
0
0
0
0
14
10
6
3
2
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
13
10
7
4
3
1
1
1
1
1
1
0
0
16
11
7
4
3
1
1
1
1
10
7
5
3
1
1
1
0
0
0
0
0
0
0
24
17
11
6
4
3
2
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
23
17
12
7
5
3
3
2
1
1
1
1
1
28
20
12
7
5
3
2
1
1
17
13
9
5
4
3
2
0
0
0
0
0
0
0
39
29
18
10
7
4
4
3
2
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
38
28
20
11
8
5
4
4
2
1
1
1
1
46
32
20
12
9
6
4
3
3
27
21
15
8
6
4
4
0
0
0
0
0
0
0
68
49
31
18
13
8
6
5
4
3
3
2
1
1
1
1
1
1
1
1
1
0
0
0
66
48
34
19
14
10
8
6
4
4
3
2
1
79
56
34
21
15
10
7
6
5
47
36
27
15
11
8
7
1
1
0
0
0
0
0
91
67
42
24
17
10
9
7
5
4
4
3
2
1
1
1
1
1
1
1
1
1
1
1
89
65
46
26
19
13
11
9
6
5
4
3
3
107
76
46
29
20
14
10
8
7
64
49
36
20
15
11
9
1
1
1
1
1
0
0
149
109
68
39
28
17
15
12
9
8
6
5
4
3
3
2
2
1
1
1
1
1
1
1
145
106
76
43
31
21
18
15
10
8
7
6
5
175
124
76
48
33
23
17
14
11
104
80
59
33
24
18
15
13
1
1
1
1
1
1
1
211
154
97
56
40
25
21
17
13
11
9
7
6
5
4
4
3
3
2
1
1
1
1
1
205
150
107
61
44
30
25
21
14
12
10
8
7
247
175
107
68
47
33
24
20
16
147
113
84
47
35
25
21
2
2
1
1
1
1
1
326
238
150
86
62
38
32
27
20
17
14
12
9
8
7
6
5
4
3
3
3
3
2
2
317
231
166
95
67
47
39
32
22
19
15
13
10
381
271
166
105
73
50
37
30
25
228
175
130
72
53
39
33
3
3
3
1
1
1
1
436
318
200
115
83
51
43
36
27
23
19
16
13
10
9
8
7
6
5
4
4
4
3
3
423
309
221
127
90
63
52
43
30
25
21
17
14
510
362
221
140
98
67
49
41
33
304
234
174
97
71
52
44
4
4
3
3
2
1
1
562
410
258
149
107
66
56
47
35
29
24
20
17
13
12
10
9
7
6
5
5
5
4
4
545
398
285
163
116
81
68
56
39
32
27
22
18
657
466
285
180
127
87
63
53
43
392
301
224
124
92
67
56
14
Electric Power Systems
2
1
1/0
2/0
3/0
4/0
250
300
350
400
500
600
700
750
800
900
1000
1250
1500
1750
2000
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
2
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
5
4
3
3
2
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
7
5
5
4
3
2
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
Durham
12
9
8
6
5
4
3
3
3
2
1
1
1
1
1
1
1
1
1
1
0
18
13
11
9
7
6
5
4
4
3
3
2
1
1
1
1
1
1
1
1
1
27
20
17
14
12
10
8
7
6
5
4
3
3
3
3
2
2
1
1
1
1
37
27
23
19
16
13
11
9
8
7
6
5
4
4
4
3
3
2
1
1
1
47
35
30
25
20
17
14
12
10
9
8
6
5
5
5
4
4
3
2
2
1
Chapter 4
NEC & NEMA Standards
15
NEMA Controller Size for Motors, Transformers, & Capacitors
Load Contin- Service
Voltage uous
Limit
Current Current
NEMA
Size
00
0
1
1P
2
3
4
5
6
7
8
9
V
Amp
Amp
115
200
230
380
460
575
115
200
230
380
460
575
115
200
230
380
460
575
115
230
115
200
230
380
460
575
115
200
230
380
460
575
115
200
230
380
460
575
115
200
230
380
460
575
115
200
230
380
460
575
230
460
575
230
460
575
230
460
575
9
11
18
21
27
32
36
42
45
52
90
104
135
156
270
311
540
621
810
932
1215
1400
2250
2590
Motor
Maximum
Motor
Maximum
Non-plugging and
Non-jogging Duty
Plugging and
Jogging Duty
HP
1φ
1/3
—
1
—
—
—
1
—
2
—
—
—
2
—
3
—
—
—
3
5
3
—
7-1/2
—
—
—
7-1/2
—
15
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
HP
3φ
—
1-1/2
1-1/2
1-1/2
2
2
—
3
3
5
5
5
—
7-1/2
7-1/2
10
10
10
—
—
—
10
15
25
25
25
—
25
30
50
50
50
—
40
50
75
100
100
—
75
100
150
200
200
—
150
200
300
400
400
300
600
600
450
900
900
800
1600
1600
HP
1φ
1/4
—
1/2
—
—
—
1/2
—
1
—
—
—
1
—
2
—
—
—
1-1/2
3
2
—
5
—
—
—
7-1/2
—
15
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
HP
3φ
—
1
1
1
1-1/2
1-1/2
—
1-1/2
1-1/2
1-1/2
2
2
—
3
3
5
5
5
—
—
—
7-1/2
10
15
15
15
—
15
20
30
30
30
—
25
30
50
60
60
—
60
75
125
150
150
—
125
150
250
300
300
—
—
—
—
—
—
—
—
—
Transformer
Transformer
Capacitor
Circuit
Primary
Primary
Switching
Closing
Switching
Switching
Maximum
Inrush Current
Inrush Current
Inrush Current
< = 20 times
= 20 to 40 times
Peak Including
Continuous Amp Continuous Amp
Offset
kVA
kVA
kVA
kVA
kVAR
Amp
1φ
3φ
1φ
3φ
3φ
3φ
—
—
—
—
—
87
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0.6
—
0.3
—
—
140
—
1.8
—
0.9
—
1.2
2.1
0.6
1
—
—
—
—
—
—
2.4
4.2
1.2
2.1
—
3
5.2
1.5
2.6
—
1.2
—
0.6
—
—
288
—
3.6
—
1.8
—
2.4
4.3
1.2
2.1
6
—
—
—
—
—
4.9
8.5
2.5
4.3
13.5
6.2
11
3.1
5.3
17
—
—
—
—
—
—
—
—
—
—
—
—
2.1
—
1
—
—
483
—
6.3
—
3.1
—
4.1
7.2
2.1
3.6
12
—
—
—
—
—
8.3
14
4.2
7.2
25
10
18
5.2
8.9
31
4.1
—
2
—
—
947
—
12
—
6.1
—
8.1
14
4.1
7.0
27
—
—
—
—
—
16
28
8.1
14
53
20
35
10
18
67
6.8
—
3.4
—
—
1581
—
20
—
10
—
14
23
6.8
12
40
—
—
—
—
—
27
47
14
23
80
34
59
17
29
100
14
—
6.8
—
—
3163
—
41
—
20
—
27
47
14
24
80
—
—
—
—
—
54
94
27
47
160
68
117
34
59
200
27
—
14
—
—
6326
—
81
—
41
—
54
94
27
47
160
—
—
—
—
—
108
188
54
94
320
135
234
68
117
400
—
—
—
—
240
9470
—
—
—
—
480
—
—
—
—
600
—
—
—
—
360
14205
—
—
—
—
720
—
—
—
—
900
—
—
—
—
665
25380
—
—
—
—
1325
—
—
—
—
1670
16
Electric Power Systems
Durham
Service-Limit Current Ratings - The service-limit current ratings shown represent the maximum rms current, in amperes, which the controller
shall be permitted to carry for protracted periods in normal service. At service-limit current ratings, temperature rises shall be permitted to exceed
those obtained by testing the controller at its continuous current rating. The current rating of overload relays or the trip current of other motor
protective devices used shall not exceed the service-limit current rating of the controller.
Plugging or Jogging Service - The listed horsepower ratings are recommended for those applications requiring repeated interruption of stalled
motor current encountered in rapid motor reversal in excess of five openings or closings per minute and shall not be more than ten in a ten minute
period.
Capacitor terminals - If maximum available current is greater than 3,000 amperes, consult NEMA ICS-2 Standard.
Chapter 4
NEC & NEMA Standards
17
NEMA Table 11 Typical Characteristics and Applications of Fixed Frequency Small and
Medium AC Squirrel-Cage Induction Motors
Design Letter
Locked
Rotor
Torque
Polyphase
Percent
Characteristics Rated
Load
Torque*
70-275
Design A
High locked rotor
torque
High locked rotor
current
70-275
Design B
Normal locked
rotor torque
Normal locked
rotor current
Design C
Pullup
Torque
Percent
Rated
Load
Torque
65-190
Breakdown
Torque
Percent
Rated
Load
Torque
175-300
Locked
Slip Typical Applications
Rotor
Current
Percent Percent
Rated
Sync
Load
Speed
Current
Not
0.5-5% Fans, blowers, centrifugal pumps
defined
and compressors, motor-generator
sets, etc., where starting torque
requirements are relatively low.
Relative
Efficiency
65-190 175-300 600-700 0.5-5% Fans, blowers, centrifugal pumps
and compressors, motor-generator
sets, etc., where starting torque
requirements are relatively low.
Medium or
high
200-285 140-195 190-225 600-700
1-5%
Conveyors, crushers, stirring motors, Medium
agitators, reciprocating pumps and
compressors, etc., where starting
under load is required
High peak loads with or without
flywheels such as punch presses,
shears, elevators, extractors,
winches, hoists, oil-well pumping
and wire-drawing motors
Centrifugal loads where starting
torque requirements are relatively
low.
Low
Fans, blowers, centrifugal pumps
and compressors, motor-generator
sets, etc., where starting torque
requirements are relatively low.
Fans, blowers, centrifugal pumps
and compressors, motor-generator
sets, etc., where starting torque
requirements are relatively low.
Medium or
low
High locked rotor
torque
Normal locked
rotor current
Design D
275
NA
275
600-700
5-8%
High locked rotor
torque
High slip
Design N
-
NA
-
-
-
Small motor
Design 0
-
NA
-
-
NA
Small motor
Design L
-
100%
-
-
NA
-
100%
-
-
NA
Medium motor
Design M
Medium or
high
Medium motor
*Higher values are for motors having lower horsepower ratings.
Low
Medium or
low
18
Electric Power Systems
Durham
NEMA MOTOR DIMENSIONS
Shaft – Key Dimensions
NEMA
Shaft (U)
3/8
1/2
5/8
7/8
1-1/8
1-3/8
1-5/8
1-7/8
2-1/8
2-3/8
2-1/2
2-7/8
3-3/8
3-7/8
Frame D
42
48
56
56H
143T
145T
182
184
182T
184T
213
215
213T
215T
254U
256U
254T
256T
284U
286U
284T
286T
284TS
286TS
324U
326U
324T
326T
324TS
326TS
364U
365U
364T
365T
364TS
365TS
404U
405U
404T
405T
404TS
405TS
444U
445U
444T
445T
447T
449T
444TS
445TS
447TS
449TS
E
2F
Key (R)
Frame Dimensions
21/64
29/64
33/64
49/64
63/64
1-13/64
1-13/32
1-19/32
1-27/32
2-1/64
2-3/16
2-29/64
2-7/8
3-5/16
Dimen
(S)
flat
flat
3/16
3/16
1/4
5/16
3/8
1/2
1/2
5/8
5/8
3/4
7/8
1
N*
O*
P*
U
V
AA
AK
BA
BB
BD*
TAP
1-1/2
1-7/8
2-7/16
2-1/8
2-1/2
5
5-7/8
6-7/8
4-11/16
5-11/16
6-5/8
3/8
1/2
5/8
1-1/8
1-1/2
1-7/8
3/8
1/2
1/2
4-1/32 1-5/16 3-3/4
4-3/8 1-11/16 3-3/4
5
2-1/16 5-7/8
3
3
4-1/2
2-1/16
2-1/2
2-3/4
1/8
1/8
1/8
4-5/8
5-5/8
6-1/2
1/4-20
1/4-20
3/8-16
6-7/8
6-5/8
7/8
2-1/4
3/4
5-1/4
2-1/4
1/8
6-1/2
3/8-16
3/4
5-7/8
1/8
1/8
1/4
1/4
6-1/2
6-1/2
9
9
3/8-16
3/8-16
1/2-13
1/2-13
3/4
7-3/8
1
9-5/8
1-1/2
13-1/8
2
14-1/8
H
2-5/8 1-3/4 1-11/16 9/32 slot
3
2-1/8 2-3/4 11/32 slot
3-1/2 2-7/16
3
11/32 slot
5
3-1/2 2-3/4
4
11/32
5
4-1/2
4-1/2 3-3/4 5-1/2
13/32
4-1/2
5-1/2
5-1/2
5-1/4 4-1/4
7
13/32
5-1/2
7
8-1/4
6-1/4
5
10
17/32
8-1/4
10
9-1/2
11
7
5-1/2 9-1/2
17/32
11
9-1/2
11
10-1/2
12
8
6-1/4 10-1/2 21/32
12
10-1/2
12
11-1/4
12-1/4
9
7
11-1/4 21/32
12-1/4
11-1/4
12-1/4
12-1/4
13-3/4
10
8
12-1/4 13/16
13-3/4
12-1/4
13-3/4
14-1/2
16-1/2
14-1/2
11
9
16-1/2 13/16
20
25
14-1/2
16-1/2
20
25
2-11/16
2-11/16
3-9/16
3-9/16
3-1/2
3-1/2
3-7/8
3-7/8
4-1/16
4-1/16
4-5/16
4-5/16
5-1/8
5-1/8
4-7/8
4-7/8
3-3/8
3-3/8
5-7/8
5-7/8
5-1/2
5-1/2
3-15/16
3-15/16
6-3/4
6-3/4
6-1/4
6-1/4
4
4
7-3/16
7-3/16
7-5/16
7-5/16
4-1/2
4-1/2
8-5/8
8-5/8
8-1/2
8-1/2
8-15/16
8-15/16
5-3/16
5-3/16
4-15/16
4-15/16
7/8
7/8
1-1/8
1-1/8
1-1/8
10-1/4 9-9/16 1-1/8
1-3/8
1-3/8
1-3/8
12-7/8 12-15/16 1-3/8
1-5/8
1-5/8
1-5/8
1-5/8
14-5/8 14-5/8 1-7/8
1-7/8
1-5/8
1-5/8
1-7/8
1-7/8
2-1/8
16-1/2 16-1/2 2-1/8
1-7/8
1-7/8
2-1/8
2-1/8
18-1/2 18-1/4 2-3/8
2-3/8
1-7/8
1-7/8
2-3/8
2-3/8
20-5/16 20-1/8 2-7/8
2-7/8
2-1/8
2-1/8
22-7/8 22-3/8 2-7/8
22-7/8 22-3/8 2-7/8
22-7/8 22-3/8 3-3/8
22-7/8 22-3/8 3-3/8
22-15/16 22-3/4 3-3/8
22-15/16 22-3/4 3-3/8
22-7/8 22-3/8 2-3/8
22-7/8 22-3/8 2-3/8
22-15/16 22-3/4 2-3/8
22-15/16 22-3/4 2-3/8
8-11/16
7-7/8
2-1/4
2-1/4
2-3/4
2-3/4
3
3
3-3/8
3-3/8
3-3/4
3-3/4
4
4
4-7/8
4-7/8
4-5/8
4-5/8
3-1/4
3-1/4
5-5/8
5-5/8
5-1/4
5-1/4
3-3/4
3-3/4
6-3/8
6-3/8
5-7/8
5-7/8
3-3/4
3-3/4
7-1/8
7-1/8
7-1/4
7-1/4
4-1/4
4-1/4
8-5/8
8-5/8
8-1/2
8-1/2
8-1/2
8-1/2
4-3/4
4-3/4
4-3/4
4-3/4
AB*
2-1/2 15-1/16
3
18
19-9/16
19-9/16
19-9/16
19-9/16
3 21-11/16
21-11/16
19-9/16
19-9/16
4NPT 21-11/16
4NPT 21-11/16
AH
AJ
2-1/8
5-7/8
4-1/2
2-1/8
2-1/8
2-5/8
2-5/8
2-3/4
2-3/4
3-1/8
3-1/8
3-1/2
3-1/2
3-3/4
3-3/4
4-5/8
4-5/8
4-3/8
4-3/8
3
3
5-3/8
5-3/8
5
5
3-1/2
3-1/2
6-1/8
6-1/8
5-5/8
5-5/8
3-1/2
3-1/2
6-7/8
6-7/8
7
7
4
4
8-3/8
8-3/8
8-1/4
8-1/4
8-1/4
8-1/4
4-1/2
4-1/2
4-1/2
4-1/2
5-7/8
5-7/8
7-1/4
7-1/4
4-1/2
4-1/2
8-1/2
8-1/2
7-1/4
8-1/2
3-1/2
1/4
9
1/2-13
7-1/4
8-1/2
4-1/4
1/4
10
1/2-13
9
10-1/2
4-3/4
1/4
11-1/4 1/2-13
11
12-1/2
5-1/4
1/4
13-3/8 5/8-11
11
12-1/2
5-7/8
1/4
13-3/8 5/8-11
11
12-1/2
6-5/8
1/4
13-7/8 5/8-11
14
16
7-1/2
1/4
16-3/4 5/8-11
2-3/4
Chapter 4
NEC & NEMA Standards
19
NEMA MOTOR DIMENSIONS – 2
Frame Size Information
Notes From Front:
Suffix letters after the NEMA frame size indicates that the frame differs in some way from the
standard frame. Below is a list of suffixes that may be found after the frame size and their
definition.
A
DC Motor or Generator
C
“C” flange mounting on drive end **
D
“D” flange mounting on drive end **
E
Shaft dimensions for elevator motors in frames larger than the 326U frame
H
Frame with an “F” dimension larger than a frame without (small framed motors)
J
Jet pump motors
JM
“C”-face mounted close coupling pump with mechanical seal
JP
“C”-face mounted close coupling pump -packed pump
K
Sump pump motor
LP & LPH “P” flange mounting vertical solid shaft pump
P & PH
“P” flange mounting vertical hollow shaft pump
S
Standard short shaft
T
Included as part of a frame number-standard dimension
U
Included as part of a frame number-standard dimension
V
Vertical mounting
Y
Special mounting dimensions -manufactured specified
Z
Special shaft dimensions -manufactured specified
** If the face mounting is on the end opposite the drive, the suffix will be as follows: “FC” or “FD”
-When a “C” flange has been added to a
NEMA motor the “BA” dimensions are:
Frame:
“BA”:
143-5TC
2-3/4
182-4TC
3-1/2
213-5TC
4-1/4
254-6TC
4-3 4
-Dimensions: C, N, O, P, & AB are specific to
each manufacturer. Please call for exact
dimensions.
Assembly Position F-1 VS. F-2
F-1
F-2
Pre-NEMA Dimensions
FRAME
203
204
224
225
254
284
324
324S
326
326S
364
364S
356
365S
U
3/4
3/4
1
1
1-1/8
1-1/4
1-5/8
1-5/8
1-5/8
1-5/8
1-7/8
1-7/8
1-7/8
1-5/8
V
2
2
2-3/4
2-3/4
3-1/8
3-3/4
4-5/8
3
4-5/8
3
5-3/8
3-1/2
5-3/8
3-1/2
D
5
5
5-1/2
5-1/2
6-1/4
7
8
8
8
8
9
9
9
9
2F
5-1/2
6-1/2
6-3/4
7-1/2
8-1/14
9-1/2
10-1/2
10-1/2
12
12
11-1/4
11-1/4
12-1/4
12-1/4
E
4
4
4-1/2
4-1/2
5
5-1/2
6-1/4
6-1/4
6-1/4
6-1/4
7
7
7
7
FRAME
404
404S
405
405S
444
444S
445
445S
504
504S
505
505S
584
584S
U
2-1/8
1-7/8
2-1/8
1-7/8
2-3/8
2-1/8
2-3/8
2-1/8
2-5/8
2-1/8
2-7/8
2-1/8
2-7/8
2-3/8
V
6-1/8
3-1/2
6-1/8
3-/2
6-7/8
4
6-7/8
4
7-5/8
4
8-3/8
4
11-5/8
4-3/4
D
10
10
10
10
11
11
11
11
12-1/2
12-1/2
12-1/2
12-1/2
14-1/2
14-1/2
2F
12-1/4
12-1/4
13-3/4
13-3/4
14-1/2
14-1/2
16-1/2
16-1/2
16
16
18
18
18
18
E
8
8
8
8
9
9
9
9
8
8
9
9
9
9
Standard NEMA Frames vs Horsepower
HP T-Frame
1964Present
1 182T
1.5 184T
2 213T
3 215T
5 254T
7.5 256T
10 284T
15 286T
20 324T
25 326T
30 364T
40 365T
50 404T
60 405T
75 444T
100 445T
125 .
150 .
200 .
250 .
900 RPM
U-Frame
1952Present
213
213
215
254U
256U
284U
286U
326U
364U
365U
404U
405U
444U
445U
.
.
.
.
.
.
1200 RPM
Original T-Frame U-Frame
NEMA 19641952Present Present
225
145T
184
254
182T
184
254
184T
213
284
213T
215
324
215T
254U
326
254T
256U
364
256T
284U
365
284T
324U
404
286T
326U
405
324T
364U
444
324T
365U
445
364T
404U
504
365T
405U
505
404T
444U
.
405T
445U
.
444T
.
.
445T
.
.
..
.
.
.
.
.
.
Original T-Frame
NEMA 1964Present
204
143T
224
145T
225
145T
254
182T
284
184T
324
213T
326
215T
364
254T
365
256T
404
284T
405
286T
444
324T
445
326T
504
364TS
505
365TS
.
404TS/405TS
.
405TS/444TS
.
444TS/445TS
.
455TS
.
.
1800 RPM
U-Frame
1952Present
182
184
184
213
215
254U
256U
284U
286U
324U
326U
364U
365US
404US/405US
405US/444US
444US/445US
445US
.
.
.
Original
NEMA
T-Frame
1964Present
203
.
204
143T
224
145T
225
145T/182T
254
182T/184T
284
184T/213T
324
213T/215T
326
215T/254T
364
254T/256T
364/365
256T/284TS
365/404
284TS/286TS
404/405
286TS/324TS
405S/444 324TS/326TS
444S/445S 326TS/364TS
445S/504S 364TS/365TS
504S/505S 365TS/405TS
505S
404TS/444TS
.
405TS/445TS
.
444TS
.
445TS
These charts are provided for reference use only. We are not responsible for any printing errors.
3600 RPM
U-Frame
1952Present
.
182
184
184
213
215
254U
256U
284U/286U
286U/324U
324S/326S
326S/364US
364US
365US/405US
404US/444US
405US/445US
444US
445US
.
.
Original
NEMA
.
203
204
224
225
254
284
324
326
364S/365S
364S/404S
365S/405S
404S/444S
405S/445S
444S/504S
445S/505S
504S
505S
.
.
20
Electric Power Systems
Durham
NEMA Motor Enclosure Type
Type
Open Drip Proof
Abbreviation
ODG
ODG-FV
ODG-SV
ODP
Totally Enclosed TEAO
TEBC
TECACA
TEDC-A/A
TEDC-A/W
TEFC
TENV
TETC
TEWAC
TEXP
Weather Protected WPI
WPII
Special
XE
XL
XP
XT
IEC
IP-22
IP-44
IP-54
IP-55
Description
Open Drip-Proof, Guarded
Open Drip-Proof, Force Ventilated
Open Drip-Proof, Separately Ventilated
Open Drip-Proof
Totally-Enclosed, Air-Over
Totally-Enclosed, Blower-Cooled
Totally-Enclosed, Closed Circuit,, Air to Air
Totally-Enclosed, Dual Cooled, Air to Air
Totally-Enclosed, Dual Cooled, Air to Water
Totally-Enclosed, Fan-Cooled
Totally-Enclosed Non-Ventilated
Totally-Enclosed, Tube Cooled
Totally-Enclosed, Water/Air Cooled
Totally-Enclosed, Explosion-Proof
Weather Protected, Type I
Weather Protected Type II
Premium Efficient
Extra Life
Explosion-Proof
Extra Tough
Dust ignition proof
Open Drip-Proof
Totally-Enclosed
Splash Proof
Washdown
Designed for use in
non-hazardous, relatively clean
areas, most common type,
extremely wet, dirty, or dusty areas
adverse outdoor conditions
improved efficiency
withstanding an explosion of a
specified dust, gas, or vapor
preventing the ignition of a dust,
gas, or vapor surrounding the motor
representative IEC designations
Chapter 4
NEC & NEMA Standards
21
Electrical Power System Design Example
Pump:
20 Hp, 300 RPM, 18” sheave
Pump:
Motor:
3Φ, 460 V
Motor:
Power:
3Φ, 7200 LN
Power:
Environment:
Environment: ambient 98F, outdoor
# Measure Parameter
1 Motor horsepower
Standard Table or
Reference
NEC 430.250
2 Full load Amps - FLA
NEC 430.250
-
27
3 Lock letter code & kVA/hp
NEC 430.7(B)
F 5.59
112
4 Lock rotor amp calculate
kVA*1000/1.732 V
112,000/1.732*460
141
-
145
1.25*27 + 0
34
5 Lock rotor amp for disconnect NEC 430.251(B)
6 Wire rating:1.25*largest+other NEC 430.24
Example
Factor
-
Example
Result
20
7 Insulation type
NEC 310-16
-
THHN
8 Insulation temperature
NEC 310-16
-
90C
9 AWG / kcmil
NEC 310-16
-
10 AWG
10 Temperature correction amp
NEC 310-16
0.91
36
11 Max breaker rating & type
NEC 430.52
800 instant
216
12 Actual breaker size
NEC 240.6(A)
-
200
13 Controller enclosure
NEC 430.91
-
3R
14 Controller size
NEMA Controller
-
2
15 Controller max closing amp
NEMA Controller
-
483
105
28.4
16 Overload setting % - Amp
-
17 Motor enclosure
NEMA Enclosure
18 Motor NEMA design
NEMA 11
19 Motor sync speed
120 * freq / poles
20 Motor slip - shaft speed
NEMA 11
21 Motor frame
TEFC
-
B
120*60/4
1800
2%
1764
NEMA Dimension 2
-
256T
22 Shaft diameter
NEMA Dimensions
U
1-5/8
23 Sheave diameter
P(n*dia) = M(n*dia)
300*18/1800
3”
-
3Φ + N
4
1/2
3/4
1.732*480*27/1000
22.5
-
3 – 7.5
24 # wires
25 Conduit type & size
NEC C4 et al
26 Total kVA
1.732 V * I / 1000
26 Transformer kVA size
NEMA
28 Secondary volt & Y-∆
-
277 / 480 Y
29 Primary volt & Y-∆
-
12470 ∆
30 Transformers taps
31 Transformer impedance PU
two 2-1/2 +
Problem
Factor
Problem
Result