Wire Gauge Ampacity

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  • How much Electrical Current a wire, and to an extent a circuit, can carry
  • Important to calculate so that you don't have Electrical Fires due to Overheating
  • Copper resistivity - 100 compared to aluminum 160. [1]
  • Aluminum has about 60% the conductivity of copper, but 30% the weight for a given diameter. All together, aluminum cable is half the weight of copper for the same ampacity. [2]

Tables - Copper

  1. Engineering Toolbox - [3]
  2. Powerstream - [4]

Copper Clad Aluminum (CCA)

Free Air

  • "Directly from 4-004(1)(a), you must maintain a cable spacing not less then 100% of the larger cable diameter" - [6]

22 Ga for D3D

  • At 24V we need 5A for the main power supply, so 22 ga should be good. 80C rating of [7]. Engineering Toolbox says 1 strand is good for 5A.


  • What are the limits to motor startup current, and common house wire? See discussion at Wire Ampacity: