2023 NEC · free reference

The tables, in full.

Every figure AmpSizer calculates from, published openly with its source table cited. No paywall on any of it - a safety-relevant lookup belongs in the open. If you are not sure which of the three temperature columns your job is allowed to use, start with which ampacity column applies.

Conductor sizes, 14 AWG to 2000 kcmil

165

Ampacity values across both materials

Reference tables

432

Generated reference pages

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All tables

NEC 2023Every table listed here is transcribed from the 2023 NEC (NFPA 70, 2023). The code is republished on a three-year cycle and adoption varies by jurisdiction - confirm against your locally adopted edition and your authority having jurisdiction (AHJ) before you build.

Copper ampacityAllowable ampacity of copper conductors from 14 AWG to 2000 kcmil at 60°C, 75°C, and 90°C insulation ratings.Aluminum ampacityAllowable ampacity of aluminum and copper-clad aluminum conductors from 12 AWG to 2000 kcmil at 60°C, 75°C, and 90°C.Temperature correctionCorrection factors applied to conductor ampacity when the ambient temperature is above or below the 30°C table basis.Bundling adjustmentAdjustment factors applied when more than three current-carrying conductors share a raceway or cable.Breaker sizesThe standard ampere ratings for fuses and inverse-time circuit breakers, from 15 A to 6000 A.Grounding conductorsMinimum equipment grounding conductor size in copper and aluminum, by the rating of the overcurrent device ahead of the equipment.Conduit fillPermitted fill percentages, conduit internal areas for EMT, PVC Schedule 40, and RMC, and conductor cross-sectional areas by insulation type.Conductor propertiesCircular-mil area and DC resistance per 1000 feet for copper and aluminum conductors, the inputs to every voltage-drop estimate.

Per-conductor pages

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About this data

These are published numeric values transcribed from the 2023 NEC - table data, not code text. AmpSizer reproduces no code language, and it is not affiliated with, endorsed by, or a substitute for the code itself. If you need the actual requirements, including the exceptions and conditions the tables reference, you need the code document.

The whole dataset lives in one generated file with the edition labelled, so moving to a new edition is a single update rather than a hunt through the app. Every value is checked on build against known anchor figures and for internal consistency - ampacity has to rise with conductor size, copper has to beat aluminum at the same size, and columns have to order correctly.

Adoption is not uniform. Jurisdictions adopt editions years apart and amend them freely, so the edition cited here may not be the one enforced where you are. Confirm before you rely on any figure.

Every figure on this page comes from the 2023 NEC (NFPA 70, 2023). The code is republished on a three-year cycle and adoption varies by jurisdiction - confirm against your locally adopted edition and your authority having jurisdiction (AHJ) before you build.

Reference estimate - verify before you build. AmpSizer reports reference estimates transcribed from published tables in the 2023 NEC (NFPA 70, 2023), and from no other edition. It is not a substitute for the code adopted in your jurisdiction. The code is republished on a three-year cycle and adoption varies by jurisdiction - confirm against your locally adopted edition and your authority having jurisdiction (AHJ) before you build. Final conductor sizing, overcurrent protection, and installation must be determined by a licensed electrician and approved by your AHJ.

Jurisdictions adopt editions on their own schedule and frequently amend them, so the edition enforced where you work may not be the one cited here. Confirm which edition and which local amendments apply to your job before relying on any value on this page.