What is the maximum length of a single-phase, 120-volt branch circuit supplying a 10-ampere load with 14 AWG conductors without exceeding a voltage drop of 3.6 volts?

To determine the maximum length of a single-phase, 120-volt branch circuit that can supply a 10-ampere load using 14 AWG conductors, it's important to understand the concept of voltage drop. Voltage drop occurs when the voltage supplied to the load decreases as it travels through the conductor due to resistance.

The acceptable voltage drop is often set at a percentage of the system voltage; in this case, you want to ensure it does not exceed 3.6 volts. For a 120-volt circuit, this is approximately a 3% voltage drop, which is a commonly accepted limit.

To calculate the voltage drop per foot for 14 AWG copper wire with a current of 10 amperes, you can use the formula:

[

Voltage , Drop (V) = I \times R \times L

]

Where:

• ( I ) is the current in amperes,

• ( R ) is the resistance of the conductor (ohms per foot),

• ( L ) is the length of the conductor (in feet), and since it’s a single-phase circuit, we typically use the round trip (out and back).

For 14 AWG copper wire, the resistance is approximately