#100 AMP WIRE SIZE COPPER HOW TO#

Note: K = 12.9 for Copper conductors at 75☌ (167☏), and K = 21.2 for Aluminum conductors at 75☌ (167☏). K = Resistance in ohms of 1 circular mil foot of conductor. Voltage drop is calculated for single-phase circuits as follows:Ĭm = Cross Section Area of Condcutor (Circular Mils) The National Electrical Code states that the voltage drop of a feeder circuit must not exceed 5%, and the voltage drop of a branch circuit This formula can help you determine voltage drop across a circuit, as well as the size wire gauge you will need for your circuitīased on the maximum desired voltage drop. To calculate the voltage drop across a conductor. A simple formula was derived from Ohm's law The current flowing through the conductor multiplied by the total resistance of the conductor. This states that the voltage potential across the conductor is equal to Voltage drop is calculated using the most universal of all electrical laws: Ohm's Law.

#100 AMP WIRE SIZE COPPER HOW TO#

Source: NFPA 70, National Electrical Code, Chapter 9, Table 8 How to Calculate Voltage Drop Note: The results of this calculator are based on conductor temperatures of 75☌. Units for wire size are AWG or kcmil.ĭistance - Enter the one-way length of the wires in the circuit in feet. Wire Size - Choose the size wire in the circuit. To calculate ground wire size, use the Ground Wire Size Calculator. For three-phase circuits, four wires are required. Single-phase circuits, three wires are required. This is typically single-phase or three-phase. Phases - Select the number of phases in the circuit. Common conductors are copper and aluminum. To multiply the nameplate FLA by 1.25 for wire sizing.Ĭonductor - Choose the material used as a conductor in the wire. While three-phase voltages are typically 208V, 230V or 480V.Īmperes - Enter the maximum current in amps that will flow through the circuit. Single-phase voltages are usually 115V or 120V, Voltage - Enter the voltage at the source of the circuit.

100 amp wire size copper