Ampacity Calculator
Illustrative Cu AWG table (60/75/90°C) with a simple conductor-count derate. Click any i for detail.
Conductor
Wire size (AWG)
i
AWG
Copper conductor size. |
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|---|---|
Temp rating column
i
Temp
Illustrative NEC-style 60/75/90°C copper values. |
|
Current-carrying conductors
i
CCC
Bundle derate sketch when more than 3. |
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Ambient (°F)
i
Ambient
Shown for context; ambient correction is a simplified note only. |
How to use this calculator
- Pick AWG and temperature column.
- Enter current-carrying conductor count.
- Read base and adjusted amps.
- Verify with the actual NEC edition and a licensed electrician.
Results explained
Ampacity tables list allowable current by size and insulation temperature rating. Bundling more than three current-carrying conductors typically requires derating. This page is an educational sketch table — not a code-compliance tool.
Quick reference: illustrative Cu amps
12 AWG ≈ 20/25/30 A at 60/75/90°C before derate.
| Item | Detail |
|---|---|
| 14 AWG | 15/20/25 |
| 10 AWG | 30/35/40 |
| 4–6 CCC | ×0.8 sketch |
| 7–9 CCC | ×0.7 sketch |
Not electrical advice — follow local code and a licensed electrician.
How the estimate is built
amps = table(AWG, temp) × derate(CCC).
Example scenario
12 AWG @ 75°C, 3 CCC → 25 A base (no bundle derate).
FAQ
Aluminum wire?
Different table — not included.
Terminator rating?
Often limited to 60°C or 75°C columns in practice.
Continuous loads?
Often size to 125% — apply separately.
See Ohm’s law?
For V/I/R relationships.