Maximum Ampacity (Current Capacity) for Wire and Cable

Determine the maximum amount of electrical current (amps) that can safely flow through different wire gauges. 

Maximum Ampacties for Wire and Cable

This table provides you with the allowable ampacity (maximum current the cable can carry) that you can use with wires in conduit, raceway, cable or directly buried, assuming an ambient temperature of 86°F (30°C)

Wire Size (AWG)
Copper Conductor Temp. Rating
Aluminum Conductor Temp. Rating
14*
20A
25A
   
12*
25A
30A
20A
25A
10*
35A
40A
30A
35A
8
50A
55A
40A
45A
6
65A
75A
50A
60A
4
85A
95A
65A
75A
2
115A
130A
90A
100A
1
130A
150A
100A
115A
1/0
150A
170A
120A
135A
2/0
175A
195A
135A
150A
3/0
200A
225A
155A
175A
4/0
230A
260A
180A
205A

*National Electric Code specifies that the overcurrent protection devie (e.g. a fuse or breaker) must not exceed 30A for 10 AWG wire, 20A for 12 AWG wire and 15A for 14 AWG wire.

Ambient Temperature Above 86°F (30°C)?

If your ambient temperature is higher than 86°F (30°C) then multiply the ampacity you found in the table above by the correction factor listed under the cable insulation temperature rating below:

Temperature Range

75°F Rated Insulation
Correction Factor

90°F Rated Insulation
Correction Factor
87-89°F
31-35°C
.94
.96
96-104°F
36-40°C
0.88
0.91
105-113°F
41-45°C
0.82
0.87
114-122°F
46-50°C
0.75
0.82
123-131°F
51-55°C
0.67
0.76
132-140°F
56-60°C
0.58
0.71
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