Ampacity of Insulated Copper Wire
An example, to show you how to read this table: When operating an environment where the air temperature is 30C (86F), a piece of 6AWG insulated copper wire will be 60C (140F) when you run 55 amps through it.
In other words, it will be painfully hot to the touch and contact for more than a couple of seconds will result in severe burns. Most people can't stand to touch something for more than a few seconds if it is hotter than 40C (104F) when the weather is cold or 49C (120F) when the weather is hot.
We don't recommend that you touch any wire (insulated or otherwise) while it is drawing 55A, that's just an example to help you understand how hot 60C is.
| Conductor Size AWG or kcmil |
Allowable Ampacities At 60C |
|---|---|
| 8 | 40 amps |
| 6 | 55 |
| 4 | 70 |
| 2 | 95 |
| 1 | 110 |
| 1/0 | 125 |
| 2/0 | 145 |
The above information is applicable To conductors:
- Rated 0 through 2000 volts
- 60°C (140°F)
- Not more than three current-carrying conductors in raceway, cable, or earth (directly buried)
- Operating in an ambient temperature of 30°C (86°F)
Based on 2005 NEC, Table 310.16.
For different ambient temperatures than the one shown above, consult the NEC tables.
Temperature Limitations: The temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination, conductor, or device. Conductors with temperature ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment, correction, or both.