Table
Resistance Temperature Correction Factors
Resistance Temperature Correction Factors reference with assumptions and boundary notes.
Reference boundary
Resistance adjustment only. This table does not replace conductor ampacity correction or product temperature ratings.
Reference table
Apply temperature correction factors to copper and aluminum conductor resistance estimates.
| Conductor temperature (C) | Copper resistance factor | Aluminum resistance factor | Use |
|---|---|---|---|
| -10 | 0.882 | 0.879 | Multiply 20 C resistance by this factor |
| 0 | 0.921 | 0.919 | Multiply 20 C resistance by this factor |
| 20 | 1 | 1 | Base resistance temperature |
| 30 | 1.039 | 1.04 | Multiply 20 C resistance by this factor |
| 40 | 1.079 | 1.081 | Multiply 20 C resistance by this factor |
| 60 | 1.157 | 1.161 | Multiply 20 C resistance by this factor |
| 75 | 1.216 | 1.222 | Multiply 20 C resistance by this factor |
| 90 | 1.275 | 1.282 | Multiply 20 C resistance by this factor |
Use notes
- Use this table for preliminary reference and arithmetic checks only.
- Confirm equipment ratings, product markings, installation conditions, utility requirements, and the local authority requirements before design or field use.