formerly Table 310.15(B)(2)(a)
Ambient Temperature Correction Factors Based on 30°C (86°F)
For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities specified in the ampacity tables by the appropriate correction factor shown below.
| Ambient Temperature (°C) |
Temperature Rating of Conductor | Ambient Temperature (°F) |
||
|---|---|---|---|---|
| 60°C | 75°C | 90°C | ||
| 10 or less | 1.29 | 1.20 | 1.15 | 50 or less |
| 11-15 | 1.22 | 1.15 | 1.12 | 51-59 |
| 16-20 | 1.15 | 1.11 | 1.08 | 60-68 |
| 21-25 | 1.08 | 1.05 | 1.04 | 69-77 |
| 26-30 | 1.00 | 1.00 | 1.00 | 78-86 |
| 31-35 | 0.91 | 0.94 | 0.96 | 87-95 |
| 36-40 | 0.82 | 0.88 | 0.91 | 96-104 |
| 41-45 | 0.71 | 0.82 | 0.87 | 105-113 |
| 46-50 | 0.58 | 0.75 | 0.82 | 114-122 |
| 51-55 | 0.41 | 0.67 | 0.76 | 123-131 |
| 56-60 | — | 0.58 | 0.71 | 132-140 |
| 61-65 | — | 0.47 | 0.65 | 141-149 |
| 66-70 | — | 0.33 | 0.58 | 150-158 |
| 71-75 | — | — | 0.50 | 159-167 |
| 76-80 | — | — | 0.41 | 168-176 |
| 81-85 | — | — | 0.29 | 177-185 |
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DISCLAIMER: All tables on this site are based on the 2020 National Electric Code. The law under your local jurisdiction may be different than what is presented here. Check your local jurisdiction's laws before attempting to do electrical work.
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