Current Carrying Capacity of Copper Conductors
Current carrying capacity is defined as
the amperage a conductor can safely carry before melting occurs in the conductor and/or the insulation.
Conductor Size: The larger the circular mil area, the greater the current capacity.
Insulation: The amount of heat generated should never exceed the maximum temperature rating of the insulation material.
Ambient temperature: The higher the ambient temperature, the less heat required to reach the maximum temperature rating of the insulation.
Conductor Number: Heat dissipation is lessened as the number of individually insulated conductors, bundled together, is increased.
Installation Conditions: Restricting the heat dissipation by installing the conductor in conduit, duct, trays or raceways lessens the current carrying capacity. This restriction can be alleviated somewhat by using proper ventilation methods, forced air cooling, etc.
Given all of the variables, no simple chart can be developed. This data is for reference only to be used when developing your basic requirements.
| Current Carrying Capacity of Copper Conductors |
| Single Conductor in Free Air - Ambient Temperature 30°C |
|
AWG / (mm)
|
Amperes per Conductor
|
|
Copper Temperature
|
|
80°C
|
90°C
|
105°C
|
125°C
|
200°C
|
|
30 / (.254)
|
2
|
3
|
3
|
3
|
4
|
|
28 / (.320)
|
3
|
4
|
4
|
5
|
6
|
|
26 / (.404)
|
4
|
5
|
5
|
6
|
7
|
|
24 / (.511)
|
6
|
7
|
7
|
8
|
10
|
|
22 / (.643)
|
8
|
9
|
10
|
11
|
13
|
|
20 / (.813)
|
10
|
12
|
13
|
14
|
17
|
|
18 / (1.024)
|
15
|
17
|
18
|
20
|
24
|
|
16 / (1.29)
|
19
|
22
|
24
|
26
|
32
|
|
14 / (1.63)
|
27
|
30
|
33
|
40
|
45
|
|
12 / (2.05)
|
36
|
40
|
45
|
50
|
55
|
|
10 / (2.59)
|
47
|
55
|
58
|
70
|
75
|
|
8 / (3.26)
|
65
|
70
|
75
|
90
|
100
|
|
6 / (4.12)
|
95
|
100
|
105
|
125
|
135
|
|
4 / (5.19)
|
125
|
135
|
145
|
170
|
180
|
|
2 / (6.59)
|
170
|
180
|
200
|
225
|
240
|
|
Correction Factors - Ambient Temperatures Over 30°C
|
|
°C
|
Conductor Temperature
|
|
80°C
|
90°C
|
105°C
|
125°C
|
200°C
|
|
40
|
.88
|
.90
|
.92
|
.95
|
-----
|
|
45
|
.82
|
.85
|
.87
|
.92
|
-----
|
|
50
|
.75
|
.80
|
.82
|
.89
|
-----
|
|
55
|
.67
|
.74
|
.78
|
.86
|
-----
|
|
60
|
.58
|
.67
|
.73
|
.83
|
.91
|
|
70
|
.35
|
.52
|
.61
|
.76
|
.87
|
|
80
|
-----
|
.30
|
.46
|
.69
|
.84
|
|
90
|
-----
|
-----
|
.30
|
.61
|
.80
|
|
100
|
-----
|
-----
|
-----
|
.51
|
.77
|
|
120
|
-----
|
-----
|
-----
|
-----
|
.69
|
|
140
|
-----
|
-----
|
-----
|
-----
|
.59
|
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