Electrical Conductors - Honeywell AUTOMATIC CONTROL Engineering Manual

GENERAL ENGINEERING DATA

ELECTRICAL CONDUCTORS

Tables 20, 21, and 22 are provided as a convenience to the
reader for reference only. In all cases the National Electrical
Code and local codes take precedence.
Table 20. Ampacity of Selected Conductors.
Copper
Types
RHW 1 ,
Wire
THW 1 ,
Size Type
TW 1 TWHN 1
AWG
18 — —
16 — —
14 20 20
12 25 25
10 30 35
8 40 50
6 55 65
4 70 85
3 85 100
2 95 115
1 110 130
1/0 125 150
1 Unless specifically permitted in National Electrical Code
the overcurrent protection for conductors marked (1)
shall not exceed 15 Amperes for 14 AWG, 20 Amperes
for 12 AWG, and 30 Amperes for 10 AWG.
NOTE: Ampacity is the current in amperes a conductor
can carry continuously without exceeding its
temperature rating while operating under specified
conditions. The values shown are maximum for three
conductors in raceway in open air.
Types TF,
Cross -
section
of copper
Wire Approx-
Circular
Size imate
Mills
AWG Dia. in.
18 1620 0.106
16 2580 0.118
14 4110 0.131
12 6530 0.148
10 10,380 0.168
8 16,510 0.245
6 26,240 0.323
4 41,740 0.372
3 52,620 0.401
2 66,360 0.433
1 83,690 0.508
1/0 105,600 0.549
ENGINEERING MANUAL OF AUTOMATIC CONTROL
Fixture
Types wire types
RHH 1 ,
TF, TFF,
THHN 1
TFN, TFFN
14 6
18 8
25 17
30 23
40 28
55 —
75 —
95 —
110 —
130 —
150 —
170 —
Table 22. Physical Constants of Selected Conductors.
TW, THW Types RHW, RHH
Approx- Approx-
imate imate
Area in 2 Dia. in. 2
0.0088 0.146
0.0109 0.158
0.0135 0.204
0.0172 0.221
0.0222 0.242
0.0471 0.328
0.0819 0.397
0.1087 0.452
0.1263 0.481
0.1473 0.513
0.2027 0.588
0.2367 0.629
Table 21. Physical Constants of Electrical
Rigid Conduit or
Conduit Internal
Trade Diameter
Size in Inches
3/8 N/A
1/2 0.622
3/4 0.824
1 1.049
1-1/4 1.380
1-1/2 1.610
2 2.067
2-1/2 2.469
3 3.068
3-1/2 3.548
4 4.026
4-1/2 4.506
5 5.047
6 6.065
Types TFN,
THWN, THHN
Approx- Approx- Approx-
imate imate imate
Area n. 2 Area in 2
Dia. in.
0.0167 0.089 0.0062
0.0196 0.100 0.0079
0.0327 0.105 0.0087
0.0384 0.122 0.0117
0.0460 0.153 0.0184
0.0845 0.218 0.0373
0.1238 0.257 0.0519
0.1605 0.328 0.0845
0.1817 0.356 0.0995
0.2067 0.388 0.1182
0.2715 0.450 0.1590
0.3107 0.491 0.1893
484
Metallic Tubing.
Tubing Flexible Conduit
Internal Internal
Area in Diameter
Square in Inches
Inches (Nominal)
N/A 0.375
0.304 0.625
0.533 0.8125
0.864 1.00
1.496 1.250
2.036 1.500
3.356 2.00
4.788 2.500
7.393 3.00
9.887 3.500
12.730 4.000
15.946 N/A
20.005
28.890
Approximate dc Resistance
at 167F (75C)
Copper
Uncoated Coated
Ohm/Mft Ohm/Mft
7.95 8.45
4.89 5.29
3.14 3.26
1.98 2.05
1.24 1.29
0.778 0.809
0.491 0.510
0.308 0.321
0.245 0.254
0.194 0.201
0.154 0.160
0.122 0.127
Internal
Area in
Square
Inches
(Nominal)
0.110
0.307
0.518
0.785
1.227
1.767
3.142
4.909
7.069
9.621
12.566
N/A
Aluminum
Ohm/Mft
13.1
8.21
5.17
3.25
2.04
1.28
0.808
0.508
0.403
0.319
0.253
0.201