IBEW fistMrSandman.Net

MrSandman.Net — Practical electrical calculators for the modern IBEW wireman.
Field calculators and layout helpers for electrical work.

Wire · Ampacity

MrSandman.Net — The AI-powered guide for the modern IBEW journeyman wireman.
Find the work fast.

Quick-reference ampacity helper for common copper THHN/THWN-2 / XHHW-2 conductor sizes. This page is a planning and study tool. Verify all final selections against the current NEC and the actual installation conditions.

Material Copper
Insulation family THHN / THWN-2 / XHHW-2
Reference NEC 310.16 baseline
Use case Quick check / training
Selected conductor ampacity
—
Choose a conductor size and rating.
125% adjusted load: —
Comparison: —
Small conductor OCP note: —
Authority block
Code authority NEC Table 310.16 baseline conditions, plus related limits in 110.14(C), 240.4(D), and 310.15.
Technical foundation Conductor ampacity and load planning fundamentals.
Practical reference Common manufacturer ampacity charts tied back to the NEC baseline.
Tool limit This page does not yet apply ambient correction or conductor-count adjustment.
Common copper ampacity table used by this helper
Size 60°C 75°C 90°C

Small-conductor overcurrent protection limits still apply to 14, 12, and 10 AWG copper in typical cases. This helper shows conductor ampacity reference values, not every final OCPD outcome.

How to use this page
1. Pick the conductor size.
2. Pick the usable terminal/column rating you are allowed to use.
3. Enter the planned load.
4. Choose 125% for continuous load checks when applicable.
5. Use the result as a quick planning check, then verify the final answer against the actual NEC rules and installation conditions.