Conductor Ampacity
Pick the gauge (AWG/mm²), material and insulation and I compute the ampacity corrected for ambient temperature and conductor grouping, per NEC 310.16, and whether it carries your current.
Calculation breakdown
| Item | Value | Detail |
|---|
How it is computed · NEC 310.16
1. Base ampacity from the gauge and the
insulation column (60/75/90 °C) of NEC table 310.16, copper.
Aluminum is estimated as ≈ 78 % of copper.
2. Ambient temperature factor (base 30 °C):
21–25=1.05 · 26–30=1.00 · 31–35=0.94 · 36–40=0.88 · 41–45=0.82 · 46–50=0.75.
3. Grouping factor for current-carrying conductors
[NEC 310.15(B)]: 1–3=1.00 · 4–6=0.80 · 7–9=0.70 · 10–20=0.50.
4. Corrected ampacity = base × f_temp × f_group.
If you enter the load current, it is compared against this value.
! Reference values under a simplified model of 310.16. A real design may also require the terminal limit (60/75 °C), adjustments for more than 20 conductors, correction for sun exposure or burial, and local rules. Always verify against the current code and with a professional.
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