Determine conduit size:
conduit size
The rigid metal conduit sizing is determined by using table C.8 NEC 2008 on page 70-739. Do these steps
1. (Find cable size)
2. Apply following table Conductor
size
(AWG/
Kcmil) | MD
(TD)
16
(1/2) | MD
(TD)
21
(3/4) | MD
(TD)
27
(1) | MD
(TD)
35
(11/4) | MD
(TD)
41
(11/2) | MD
(TD)
53
(2) | MD
(TD)
63
(21/2) | MD
(TD)
78
(3) | MD
(TD)
91
(31/2) | MD
(TD)
103
(4) | MD
(TD)
129
(5) | MD
(TD)
155
(6) | 14
12
10
8
6
| 4
3
3
1
1
| 7
6
5
2
1
| 12
10
8
4
3
| 21
17
14
7
6
| 28
23
19
10
8
| 46
38
31
16
13
| 66
55
44
23
18
| 102
85
68
36
29
| 136
113
91
48
38
| 176
146
118
61
49
| 276
229
185
87
77
| 398
330
267
139
112
| 4
3
2
1
| 1
1
1
0
| 1
1
1
1
| 2
2
1
1
| 4
4
3
1
| 6
5
4
3
| 10
9
7
5
| 14
12
11
7
| 22
19
17
11
| 30
26
23
15
| 38
34
29
19
| 60
53
46
30
| 87
76
66
44
| 1/0
2/0
3/0
4/0
| 0
0
0
0
| 1
1
0
0
| 1
1
1
1
| 1
1
1
1
| 2
2
1
1
| 4
4
3
3
| 6
5
4
4
| 10
8
7
6
| 13
11
10
8
| 17
14
12
11
| 26
23
20
17
| 38
33
28
24
| 250
300
350
400
500 | 0
0
0
0
0 | 0
0
0
0
0 | 0
0
0
0
0 | 1
1
1
1
1 | 1
1
1
1
1 | 1
1
1
1
1 | 3
2
2
1
1 | 4
4
4
3
3 | 6
5
5
4
4 | 8
7
6
6
5 | 13
11
10
9
8 | 18
16
15
13
11 |
NOTE
This table is just a portion of table C.8
Apply only for RHH,RHW,RHW-2
MD stands for Metric Designator
TS stands for Trade Size
Metric
Designator | Trade
Size |
12
16
21
27
35
41
53
63
78
91
103
129
155 | 3/8
1/2
3/4
1
1 _ 1/4
1_ 1/2
2
2_ 1/2
3
3_ 1/2
4
5
6 |
The metric designators and Trade sizes are for identification purposes only and are not actual dimensions
Apply the table C.8:
If cable type is RHH, or RHW, or RHW-2
Cable size is 14 AWG, then:
Maximum 4 cables can be combined in a ½ inch rigid metal conduit size.
Electrical wire color code chart
Design Tools
Reference
National Electrical Code 2008
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