AREA OF CONDUCTOR TYPES
APPROXIMATE DIMENSIONS OF CONDUCTORS
Size of Conductor
Type of Conductor
(AWG or kcmil)
18
RFH-2, FFH-2
16
14
12
10
8
6
4
3
2
1
1/0
2/0
3/0
4/0
250
RHH, RHW, RHW-2
300
350
400
500
600
700
750
800
900
1000
1250
1500
1750
2000
18
SF-2, SFF-2
16
14
SF-1, SFF-1
18
RFH-1, XF, XFF
18
TF, TFF, XF, XFF
16
TW, XF, XFF, THHW, THW,
14
THW-2
AREA OF CONDUCTOR TYPES
Diameter (in.)
Area (in.2)
0.136
0.148
0.193
0.212
0.236
0.326
0.364
0.412
0.440
0.472
0.582
0.622
0.668
0.720
0.778
0.895
0.950
1.001
1.048
1.133
1.243
1.314
1.348
1.380
1.444
1.502
1.729
1.852
1.966
2.072
0.121
0.133
0.148
0.091
0.106
0.118
0.0145
0.0172
0.0293
0.0353
0.0437
0.0835
0.1041
0.1333
0.1521
0.1750
0.2660
0.3039
0.3505
0.4072
0.4754
0.6291
0.7088
0.7870
0.8626
1.0082
1.2135
1.3561
1.4272
1.4957
1.6377
1.7719
2.3479
2.6938
3.0357
3.3719
0.0115
0.0139
0.0172
0.0065
0.0080
0.0109
0.133
0.0139
AREA OF CONDUCTOR TYPES
AREA OF CONDUCTOR TYPES
APPROXIMATE DIMENSIONS OF CONDUCTORS
Size of Conductor
Type of Conductor
Diameter (in.)
Area (in.2)
(AWG or kcmil)
12
0.152
0.0181
TW, THHW, THW, THW-2
10
0.176
0.0243
8
0.236
0.0437
RHH, RHW, RHW-2
14
0.163
0.0209
RHH, RHW, RHW-2, XF, XFF
12
0.182
0.0260
RHH, RHW, RHW-2, XF, XFF
10
0.206
0.0333
RHH, RHW, RHW-2
8
0.266
0.0556
6
0.304
0.0726
4
0.352
0.0973
3
0.380
0.1134
2
0.412
0.1333
1
0.492
0.1901
1/0
0.532
0.2223
2/0
0.578
0.2624
3/0
0.630
0.3117
4/0
0.688
0.3718
250
0.765
0.4596
300
0.820
0.5281
TW, THW, THHW, THW-2,
350
0.871
0.5958
RHH, RHW, RHW-2
400
0.918
0.6619
500
1.003
0.7901
600
1.113
0.9729
700
1.184
1.1010
750
1.218
1.1652
800
1.250
1.2272
900
1.314
1.3561
1000
1.372
1.4784
1250
1.539
1.8602
1500
1.662
2.1695
1750
1.776
2.4773
2000
1.882
2.7818
18
0.084
0.0055
TFN, TFFN
16
0.096
0.0072
TFE, PFAH
1
0.422
0.1399
1/0
0.462
0.1676
2/0
0.508
0.2027
TFE, PFA, PFAH, Z
3/0
0.560
0.2463
4/0
0.618
0.3000
Note: Type RHH, RHW, and RHW-2 conductors referenced on this page are without outer an covering.
AREA OF CONDUCTOR TYPES
APPROXIMATE DIMENSIONS OF CONDUCTORS
Size of Conductor
(AWG or kcmil)
Diameter (in.)
Area (in.2)
14
12
10
8
6
4
3
2
1
0.111
0.130
0.164
0.236
0.254
0.324
0.352
0.384
0.446
0.0097
0.0133
0.0211
0.0366
0.0507
0.0824
0.0973
0.1158
0.1562
1/0
2/0
3/0
4/0
0.486
0.532
0.584
0.642
0.1855
0.2223
0.2679
0.3237
250
300
0.711
0.766
0.3970
0.4608
THHN, THWN, THWN-2
350
400
500
600
700
750
800
900
1000
0.817
0.864
0.949
1.051
1.122
1.156
1.188
1.252
1.310
0.5242
0.5863
0.7073
0.8676
0.9887
1.0496
1.1085
1.2311
1.3478
PF, PGFF, PGF, PFF, PTF, PAF,
PTFF, PAFF
18
16
0.086
0.098
0.0058
0.0075
PF, PGFF, PGF, PFF, PTF, PAF,
PTFF, PAFF, TFE, FEP, PFA,
FEPB, PFAH
14
0.113
0.0100
TFE, FEP, PFA, FEPB, PFAH
12
10
8
6
4
3
2
0.132
0.156
0.206
0.244
0.292
0.320
0.352
0.0137
0.0191
0.0333
0.0468
0.0670
0.0804
0.0973
ZF, ZFF
18
16
0.076
0.088
0.0045
0.0061
Type of Conductor
THHN, THWN, THWN-2
AREA OF CONDUCTOR TYPES
AREA OF CONDUCTOR TYPES
AREA OF CONDUCTOR TYPES
APPROXIMATE DIMENSIONS OF CONDUCTORS
Type of Conductor
Size of Conductor (AWG or kcmil)
Z, ZF, ZFF
14
12
10
8
6
Z
4
3
2
1
14
12
10
8
XHHW, ZW, XHHW-2, XHH
6
4
3
2
1
1/0
2/0
3/0
4/0
250
300
350
400
500
XHHW, XHHW-2, XHH
600
700
750
800
900
1000
1250
1500
1750
2000
18
16
KF-2, KFF-2
14
12
10
18
16
KF-1, KFF-1
14
12
10
Diameter (in.)
0.103
0.122
0.156
0.196
0.234
0.282
0.330
0.362
0.402
0.133
0.152
0.176
0.236
0.274
0.322
0.350
0.382
0.442
0.482
0.528
0.580
0.638
0.705
0.760
0.811
0.858
0.943
1.053
1.124
1.158
1.190
1.254
1.312
1.479
1.602
1.716
1.822
0.063
0.075
0.090
0.109
0.133
0.057
0.069
0.084
0.103
0.127
Area (in.2)
0.0083
0.0117
0.0191
0.0302
0.0430
0.0625
0.0855
0.1029
0.1269
0.0139
0.0181
0.0243
0.0437
0.0590
0.0814
0.0962
0.1146
0.1534
0.1825
0.2190
0.2642
0.3197
0.3904
0.4536
0.5166
0.5782
0.6984
0.8709
0.9923
1.0532
1.1122
1.2351
1.3519
1.7180
2.0157
2.3127
2.6073
0.0031
0.0044
0.0064
0.0093
0.0139
0.0026
0.0037
0.0055
0.0083
0.0127
CONDUIT FILL EXAMPLES
Conduit fill is generally based on 40% of the cross-sectional area of the conduit.
Sections of conduit 24” or less in length may be filled to 60%.
APPROXIMATE DIMENSIONS OF COMPACT CONDUCTORS
BARE
THHW AND THW
Size of
CONDUCTORS
THHN CONDUCTORS
Conductor CONDUCTOR
App. Diameter
App. Diameter
(AWG or
(in.)
Area (in.2)
(in.)
Area (in.2)
kcmil)
Diameter (in.)
8
0.134
0.255
0.0510
—
—
6
0.169
0.290
0.0660
0.240
0.0452
4
0.213
0.335
0.0881
0.305
0.0730
2
0.268
0.390
0.1194
0.360
0.1017
1
0.299
0.465
0.1698
0.415
0.1352
1/0
0.336
0.500
0.1963
0.450
0.1590
2/0
0.376
0.545
0.2332
0.495
0.1924
3/0
0.423
0.590
0.2733
0.540
0.2290
4/0
0.475
0.645
0.3267
0.595
0.2780
250
0.520
0.725
0.4128
0.670
0.3525
300
0.570
0.775
0.4717
0.720
0.4071
350
0.616
0.820
0.5281
0.770
0.4656
400
0.659
0.865
0.5876
0.815
0.5216
500
0.736
0.940
0.6939
0.885
0.6151
600
0.813
1.050
0.8659
0.985
0.7620
700
0.877
1.110
0.9676
1.050
0.8659
750
0.908
1.150
1.0386
1.075
0.9076
XHHW CONDUCTORS
App. Diameter
(in.)
Area (in.2)
0.224
0.0394
0.260
0.0530
0.305
0.0730
0.360
0.1017
0.415
0.1352
0.450
0.1590
0.490
0.1885
0.540
0.2290
0.590
0.2733
0.660
0.3421
0.715
0.4015
0.760
0.4536
0.800
0.5026
0.880
0.6082
0.980
0.7542
1.050
0.8659
1.090
0.9331
To find the number of conductors allowed in a conduit:
1
2
ex.
1
2
ex.
Find the available area in square inches of the raceway.
Divide the available area of the conduit by the area of the conductors.
Chapter 9, Table 1 of the NEC provides us with the maximum percentage of fill allowed for raceways.
Chapter 9, Table 4 provides us with the area of raceways, and Chapter 9, Table 5 of the NEC
gives us the area of conductors.
A section of 1 in. EMT, 18” long would be allowed to contain how many 8 AWG XHHW conductors?
.519 (60% area of 1 in. EMT)
= 11.8 = 12, 8 AWG, XHHW conductors are allowed in this raceway
.0437 (area of 8 AWG XHHW)
Round up only where the fraction is .8 or larger and all of the conductors are the same size.
A 1-1/4 in. rigid metal conduit 30 ft. long contains 12, 10 AWG, THWN conductors; how many 12 AWG, THHN
conductors may be added?
1
.610 (40% area of 1-1/4 in. RMC) − (.0211 × 12) (area of 10 AWG, THWN) = .3568 (remaining area)
2
.3568 (remaining area)
= 26.8 = 26, 12 AWG, THHN conductors are allowed in this raceway
.0133 (area of 12 AWG, THHN)
Note: The provision that allows the next higher number of conductors to be installed in the raceway where the calculation
results in a decimal of .8 or larger may only be used where all of the conductors in the raceway are the same size.
Tables found in Annex C of the NEC can only be used where there are more than three conductors in the raceway,
all of the conductors are the same size and type, and the raceway is longer than 24”. (The following tables are
based on 40% conduit fill.)
CONDUIT FILL EXAMPLES
40% CONDUIT FILL (EMT)