The lookup rather than the arithmetic: how many conductors of one size the National Electrical Code permits in each conduit. Every figure below is the 40 percent fill limit that applies to three or more conductors, with the Chapter 9 Note 7 rounding rule applied, which is what makes these tables agree with NEC Annex C rather than with a plain division.
THHN and THWN conductors
THHN is the building wire most of this applies to. Counts are for conductors all of one size; a mixed pull has to be worked out by area, which is what the calculator does.
EMT: maximum THHN conductors at 40 percent fill
AWG
1/2 in
3/4 in
1 in
1-1/4 in
1-1/2 in
2 in
2-1/2 in
3 in
3-1/2 in
4 in
14
12
22
35
61
84
138
241
364
476
608
12
9
16
26
45
61
101
176
266
347
443
10
5
10
16
28
38
63
111
167
219
279
8
3
6
9
16
22
36
64
96
126
161
6
2
4
7
12
16
26
46
69
91
116
4
1
2
4
7
10
16
28
43
56
71
3
1
1
3
6
8
13
24
36
47
60
2
1
1
3
5
7
11
20
30
40
51
1
1
1
1
4
5
8
15
22
29
37
1/0
–
1
1
3
4
7
12
19
25
32
2/0
–
1
1
2
3
6
10
16
20
26
3/0
–
1
1
1
3
5
8
13
17
22
4/0
–
–
1
1
2
4
7
11
14
18
IMC: maximum THHN conductors at 40 percent fill
AWG
1/2 in
3/4 in
1 in
1-1/4 in
1-1/2 in
2 in
2-1/2 in
3 in
3-1/2 in
4 in
14
14
24
39
68
91
149
211
326
436
562
12
10
17
29
49
67
109
154
238
318
410
10
6
11
18
31
42
69
97
150
200
258
8
3
6
10
18
24
39
56
86
115
149
6
2
4
7
13
17
28
40
62
83
107
4
1
3
4
8
11
17
25
38
51
66
3
1
2
4
6
9
15
21
32
43
56
2
1
1
3
5
7
12
17
27
36
47
1
1
1
2
4
5
9
13
20
27
35
1/0
–
1
1
3
4
8
11
17
23
29
2/0
–
1
1
3
4
6
9
14
19
24
3/0
–
1
1
2
3
5
7
12
16
20
4/0
–
–
1
1
2
4
6
9
13
17
RMC (rigid): maximum THHN conductors at 40 percent fill
AWG
1/2 in
3/4 in
1 in
1-1/4 in
1-1/2 in
2 in
2-1/2 in
3 in
3-1/2 in
4 in
14
13
22
36
63
85
140
200
309
412
531
12
9
16
26
46
62
102
146
225
301
387
10
6
10
17
29
39
64
92
142
189
244
8
3
6
9
16
22
37
53
82
109
140
6
2
4
7
12
16
27
38
59
79
101
4
1
2
4
7
10
16
23
36
48
62
3
1
1
3
6
8
14
20
31
41
53
2
1
1
3
5
7
11
17
26
34
44
1
1
1
1
4
5
8
12
19
25
33
1/0
–
1
1
3
4
7
10
16
21
27
2/0
–
1
1
2
3
6
8
13
18
23
3/0
–
1
1
1
3
5
7
11
15
19
4/0
–
–
1
1
2
4
6
9
12
16
PVC Sch 40: maximum THHN conductors at 40 percent fill
AWG
1/2 in
3/4 in
1 in
1-1/4 in
1-1/2 in
2 in
2-1/2 in
3 in
3-1/2 in
4 in
14
11
21
34
60
82
135
193
299
401
517
12
8
15
25
43
59
99
141
218
293
377
10
5
9
15
27
37
62
89
137
184
238
8
3
5
9
16
21
36
51
79
106
137
6
1
4
6
11
15
26
37
57
77
99
4
1
2
4
7
9
16
22
35
47
61
3
1
1
3
6
8
13
19
30
40
51
2
1
1
3
5
7
11
16
25
33
43
1
–
1
1
3
5
8
12
18
25
32
1/0
–
1
1
3
4
7
10
15
21
27
2/0
–
1
1
2
3
6
8
13
17
22
3/0
–
1
1
1
3
5
7
11
14
18
4/0
–
–
1
1
2
4
6
9
12
15
PVC Sch 80: maximum THHN conductors at 40 percent fill
AWG
1/2 in
3/4 in
1 in
1-1/4 in
1-1/2 in
2 in
2-1/2 in
3 in
3-1/2 in
4 in
14
9
17
28
51
70
118
170
265
358
464
12
6
12
20
37
51
86
124
193
261
338
10
4
7
13
23
32
54
78
122
164
213
8
2
4
7
13
18
31
45
70
95
123
6
1
3
5
9
13
22
32
51
68
89
4
1
1
3
6
8
14
20
31
42
54
3
1
1
3
5
7
12
17
26
35
46
2
–
1
2
4
6
10
14
22
30
39
1
–
1
1
3
4
7
10
16
22
29
1/0
–
1
1
2
3
6
9
14
18
24
2/0
–
–
1
1
3
5
7
11
15
20
3/0
–
–
1
1
2
4
6
9
13
17
4/0
–
–
1
1
1
3
5
8
10
14
XHHW conductors
XHHW insulation is thicker than THHN at the same conductor size, so fewer fit in the same conduit. The difference is largest at the small sizes, where insulation is most of the diameter.
EMT: maximum XHHW conductors at 40 percent fill
AWG
1/2 in
3/4 in
1 in
1-1/4 in
1-1/2 in
2 in
2-1/2 in
3 in
3-1/2 in
4 in
14
8
15
25
43
58
96
168
254
332
424
12
6
11
19
33
45
74
129
195
255
326
10
5
8
14
24
33
55
96
145
190
243
8
2
5
8
13
18
30
53
81
105
135
6
1
3
6
10
14
22
39
60
78
100
4
1
2
4
7
10
16
28
43
56
72
3
1
1
3
6
8
14
24
36
48
61
2
1
1
3
5
7
11
20
31
40
51
1
1
1
1
4
5
8
15
23
30
38
1/0
–
1
1
3
4
7
13
19
25
32
2/0
–
1
1
2
3
6
10
16
21
27
3/0
–
1
1
1
3
5
9
13
17
22
4/0
–
–
1
1
2
4
7
11
14
18
The rules behind the numbers
One conductor may fill 53 percent of the conduit, exactly two may fill 31 percent, and three or more may fill 40 percent. The two-conductor case is the strictest because two round conductors leave the most unusable space between them.
Chapter 9 Note 7 says that when the calculation comes out to 0.8 of a conductor or more, you round up. Without it these tables disagree with Annex C in about a third of cells, always by one conductor.
Equipment grounding conductors count toward fill even though they carry no current in normal operation.
Nipples no longer than 24 inches are permitted 60 percent fill under Chapter 9 Note 4.
Fill is a mechanical and thermal limit, not an ampacity limit. More than three current-carrying conductors in a raceway also triggers the 310.15 adjustment factors, which is a separate reduction.
Printable conduit fill chart
The THHN tables on one page, for the van or the job box.
Conduit fill chart, THHN (PDF): EMT, IMC, RMC, PVC 40 and PVC 80 against 14 AWG through 4/0. Reproduces NEC Annex C. CC BY 4.0.
Common questions
How many 12 AWG THHN wires fit in 3/4 inch EMT?
Sixteen, at the 40 percent fill limit that applies to three or more conductors. That is the figure in NEC Annex C Table C.1, and it includes any equipment grounding conductor in the same raceway.
How many 12 AWG THHN wires fit in 1/2 inch EMT?
Nine at 40 percent fill. Half-inch EMT is the most common size to run out of room first, which is why the jump to 3/4 inch nearly doubles what you can pull.
Does the ground wire count toward conduit fill?
Yes. Every conductor in the raceway counts toward the cross-sectional area, including equipment grounding conductors, even though they carry no current under normal conditions.
Why does two conductors allow less fill than three?
Because two round conductors in a round conduit leave more unusable space between them than three or more do, and a two-conductor pull is harder on the insulation. The Code sets 31 percent for exactly two against 40 percent for three or more.
What is Note 7 and why does it matter?
Chapter 9 Note 7 permits rounding up when the calculated number of conductors comes out to 0.8 or more of the next conductor. It is the difference between these tables and a plain division, and without it a chart under-reports by one conductor in roughly a third of cells.