National Electrical Code |
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| Temperature
Correction Factors For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities shown in Table 310-16 or 310-17 by the appropriate factor shown below. |
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| Ambient
Temp. °C |
60°C | 75°C | 90°C |
| 30 | 1.00 | 1.00 | 1.00 |
| 40 | .82 | .88 | .91 |
| 50 | .58 | .75 | .82 |
| 60 | .... | .58 | .71 |
| 70 | .... | .33 | .58 |
| 80 | .... | .... | .41 |
| Adjustment
Factors for More than Three Current-Carrying Conductors in a Raceway or
Cable Where the number of current-carrying conductors in a raceway or cable exceeds three, the allowable ampacities shall be reduced as shown in the following table. |
|
| Number of Current Carrying Conductors* | Percent of Values in Tables as Adjusted for Ambient Temperature |
| 4 through 6 | 80 |
| 7 through 9 | 70 |
| 10 through 20 | 50 |
| 21 through 30 | 45 |
| 31 through 40 | 40 |
| 41 and above | 35 |
| * Does not include ground |
| Table 310-16 |
| Allowable Ampacities of Insulated Conductors |
| Table 310-17 |
| Allowable Ampacities of Single Insulated Conductors |
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