The maximum frequency show is for 100% skin depth (ie. The skin effect causes the effective resistance of the conductor to increase with the frequency of the current. That is, the electric current tends to flow at the "skin" of the conductor.
Skin Effect and Skin Depth: Skin effect is the tendency of an alternating electric current (AC) to distribute itself within a conductor so that the current density near the surface of the conductor is greater than that at its core. 10 AWG - maximum of 40 Amps in free air, maximum of 30 Amps as part of a 3 conductor cable.Ĭheck your local electrical code for the correct current capacity (ampacity) for mains and in wall wiring.12 AWG - maximum of 25 Amps in free air, maximum of 20 Amps as part of a 3 conductor cable.14 AWG - maximum of 20 Amps in free air, maximum of 15 Amps as part of a 3 conductor cable.The National Electrical Code (NEC) notes the following ampacity for copper wire at 30 Celsius: Aluminum wire has a conductivity of approximately 61% of copper.Ĭurrent (ampacity): The current ratings shown in the table have been determined using the rule of 1 amp per 700 circular mils, which is a very conservative rating.
For a given current, use the noted resistance and apply Ohms Law to calculate the voltage drop across the conductor. Resistance: The resistance noted above is for copper conductors. 8 AWG.) This quadruples the cross-sectional area and the ampacity.ĭiameter: A mil is a unit of length equal to 0.001 inch (a "milli-inch" or a "thousandth of one inch") ie. The general rule of thumb is when the diameter of a wire is doubled, the AWG will decrease by 6. In North America, the most wire is produced in the standard American Wire. AWG: American Wire Gauge (AWG) is a standardized wire gauge system used predominantly in the United States to note the diameter of electrically conducting wire. Definition: The system of notation for measuring the size of conductors or wires.
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