Table
Resistance Temperature Correction Factors
Resistance Temperature Correction Factors lookup table with assumptions and boundary notes.
Scope
Resistance adjustment only. This table does not replace conductor ampacity correction or product temperature ratings.
Lookup table
Apply temperature correction factors to copper and aluminum conductor resistance estimates.
Scroll sideways to keep row labels aligned with hidden columns.
| 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 |
Notes
- Check table values for preliminary lookup and arithmetic checks only.
- Confirm equipment ratings, product markings, installation conditions, utility requirements, and the local authority requirements before design or field use.