| Temperature difference (ΔT) based on comparisons between similar components under similar loading. | Temperature difference (ΔT) based upon comparisons between component and ambient air temperatures. | Recommended Action |
|---|---|---|
| 1°C - 3°C | 1°C - 10°C | Possible deficiency; warrants investigation |
| 4°C - 15°C | 11°C - 20°C | Indicates probable deficiency; repair as time permits |
| ----- | 21°C - 40°C | Monitor until corrective measures can be accomplished |
| >15°C | >40°C | Major discrepancy; repair immediately |
Temperature specifications vary depending on the exact type of equipment. Even in the same class of equipment (i.e., cables) there are various temperature ratings. Heating is generally related to the square of the current; therefore, the load current will have a major impact on ΔT.
References: ANSI/NETA-ATS 2013, Table 100.18.
