3 Conductor - Underground Ducts

3 conductor cable underground ducts

Three conductor cable
underground ducts

One cable per duct, all cables equally loaded and in outside ducts only.

Earth ambient temperature 20°C
Earth thermal resistivity RHO 90.
100% load factor

Depth of burial - 30” to top of duct bank with duct on 7 1/2 centers.

 

One circuit — one cable in duct bank

Three conductor
Copper - underground ducts
Three conductor
Aluminum - underground ducts

Conductor
Size
AWG-kcmil

Non-Shielded

Shielded

600-2000 Volts
Ampacity

2001-5000 Volts
Ampacity

5001-35000 Volts
Ampacity

90° C
(194°F)

90° C
(194°F)

105°C
(221°F)

90° C
(194°F)

105°C
(221°F)

8.........
.
6
.........
4
.........
2
.........
1
.........
1/0
.........
2/0
.........
3/0
.........
4/0
.........
250
.........
350
.........
500
.........
750
.........
1000
........\

59.........
78
.........
102
.........
133
.........
154
.........
177
.........
202
.........
231
.........
264
.........
292
.........
354
.........
429
.........
529
.........
599
.........

59...
78
...
100
...
135
...
155
...
175
...
200
...
230
...
265
...
290
...
355
...
430
...
530
...
600
...

64...
84
...
110
...
145
...
165
...
190
...
220
...
250
...
285
...
315
...
380
...
460
...
570
...
645
...

...
88
...
115
...
150
...
170
...
195
...
220
...
250
...
285
...
310
...
375
...
450
...
545
...
615
...

...
95
...
125
...
160
...
185
...
210
...
235
...
270
...
305
...
335
...
400
...
485
...
585
...
660
...

Non-Shielded

Shielded

600-2000 Volts
Ampacity

2001-5000 Volts
Ampacity

5001-35000 Volts
Ampacity

90° C
(194°F)

90° C
(194°F)

105°C
(221°F)

90° C
(194°F)

105°C
(221°F)

46.........
61
.........
80
.........
104
.........
120
.........
138
.........
158
.........
180
.........
206
.........
228
.........
278
.........
340
.........
426
.........
495
.........

46...
61
...
80
...
105
...
120
...
140
...
160
...
180
...
205
...
230
...
280
...
340
...
425
...
495
...

50...
66
...
86
...
110
...
130
...
150
...
170
...
195
...
220
...
245
...
310
...
365
...
460
...
535
...

...
69
...
89
...
115
...
135
...
150
...
170
...
195
...
220
...
245
...
295
...
355
...
440
...
510
...

...
74
...
96
...
125
...
145
...
165
...
185
...
210
...
240
...
265
...
315
...
385
...
475
...
545
...

 

Three circuits — three cables in duct bank

Three conductor
Copper - underground ducts
Three conductor
Aluminum - underground ducts

Conductor
Size
AWG-kcmil

Non-Shielded

Shielded

600-2000 Volts
Ampacity

2001-5000 Volts
Ampacity

5001-35000 Volts
Ampacity

90° C
(194°F)

90° C
(194°F)

105°C
(221°F)

90° C
(194°F)

105°C
(221°F)

8.........
.
6.........
4.........
2.........
1.........
1/0.........
2/0.........
3/0.........
4/0.........
250.........
350.........
500.........
750.........
1000.........

53.........
69
.........
89
.........
116
.........
133
.........
151
.........
172
.........
196
.........
223
.........
245
.........
294
.........
354
.........
430
.........
484
.........

53...
69
...
89
...
115
...
135
...
150
...
170
...
195
...
225
...
245
...
295
...
355
...
430
...
485
...

57...
74
...
96
...
125
...
145
...
165
...
185
...
210
...
240
...
265
...
315
...
380
...
465
...
520
...

...
75
...
97
...
125
...
140
...
160
...
185
...
205
...
230
...
255
...
305
...
360
...
430
...
485
...

...
81
...
105
...
135
...
155
...
175
...
195
...
220
...
250
...
270
...
325
...
385
...
465
...
515
...

Non-Shielded

Shielded

600-2000 Volts
Ampacity

2001-5000 Volts
Ampacity

5001-35000 Volts
Ampacity

90° C
(194°F)

90° C
(194°F)

105°C
(221°F)

90° C
(194°F)

105°C
(221°F)

41.........
54
.........
70
.........
90
.........
103
.........
118
.........
135
.........
153
.........
174
.........
191
.........
231
.........
280
.........
347
.........
399
.........

41...
54
...
70
...
90
...
105
...
120
...
135
...
155
...
175
...
190
...
230
...
280
...
345
...
400
...

44...
58
...
75
...
97
...
110
...
125
...
145
...
165
...
185
...
205
...
250
...
300
...
375
...
430
...

...
59
...
75
...
100
...
110
...
125
...
140
...
160
...
180
...
200
...
240
...
285
...
350
...
400
...

...
64
...
81
...
105
...
120
...
135
...
155
...
175
...
195
...
215
...
255
...
305
...
375
...
430
...

 

Six circuits — six cables in duct bank

Three conductor
Copper - underground ducts
Three conductor
Aluminum - underground ducts

Conductor
Size
AWG-kcmil

Non-Shielded

Shielded

600-2000 Volts
Ampacity

2001-5000 Volts
Ampacity

5001-35000 Volts
Ampacity

90° C
(194°F)

90° C
(194°F)

105°C
(221°F)

90° C
(194°F)

105°C
(221°F)

8.........
.
6.........
4.........
2.........
1.........
1/0.........
2/0.........
3/0.........
4/0.........
250.........
350.........
500.........
750.........
1000.........

46.........
70
.........
77
.........
98
.........
112
.........
127
.........
144
.........
163
.........
185
.........
202
.........
242
.........
289
.........
348
.........
390
.........

46...
60
...
77
...
98
...
110
...
125
...
145
...
165
...
185
...
200
...
240
...
290
...
350
...
390
...

50...
65
...
83
...
105
...
120
...
135
...
155
...
175
...
200
...
220
...
270
...
310
...
375
...
420
...

...
63
...
81
...
105
...
115
...
130
...
150
...
170
...
190
...
205
...
245
...
290
...
340
...
380
...

...
68
...
87
...
110
...
125
...
145
...
160
...
180
...
200
...
220
...
275
...
305
...
365
...
405
...

Non-Shielded

Shielded

600-2000 Volts
Ampacity

2001-5000 Volts
Ampacity

5001-35000 Volts
Ampacity

90° C
(194°F)

90° C
(194°F)

105°C
(221°F)

90° C
(194°F)

105°C
(221°F)

36.........
46
.........
60
.........
77
.........
87
.........
99
.........
112
.........
128
.........
144
.........
158
.........
190
.........
228
.........
281
.........
322
.........

36...
46
...
60
...
77
...
87
...
99
...
110
...
130
...
145
...
160
...
190
...
230
...
280
...
320
...

39...
50
...
65
...
83
...
94
...
105
...
120
...
140
...
155
...
170
...
205
...
245
...
305
...
345
...

...
49
...
63
...
80
...
90
...
105
...
115
...
130
...
150
...
160
...
190
...
230
...
275
...
315
...

...
53
...
68
...
86
...
98
...
110
...
125
...
140
...
160
...
170
...
205
...
245
...
295
...
335
...