NEC 2011: Table 310.15(B)(2)(a)
| Ambient Temperature Correction Factors | ||||
| For ambient temps of other than 30C (86F), multiply allowable ampacities shown in ampacity tables by the appropriate factor shown below | ||||
| Ambient Temp (C) | Temperature Rating of Conductor | Ambient Temp (F) | ||
| 60ºC | 75ºC | 90ºC | ||
| 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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