What is the minimum size copper wire required for a 120-volt, single-phase circuit supplying a 30-ampere load over a distance of 205 feet?

To determine the minimum size copper wire required for a 120-volt, single-phase circuit supplying a 30-ampere load over a distance of 205 feet, we must consider the concepts of voltage drop and wire gauge.

For a 120-volt circuit, the acceptable voltage drop is typically a percentage of the total voltage. A common standard is to allow for a maximum voltage drop of 3% for feeders, which would equate to approximately 3.6 volts for a 120-volt system. Considering that the circuit is delivering a 30-ampere load, a longer distance contributes to a more significant voltage drop, necessitating the use of a larger wire to minimize this drop.

Using American Wire Gauge (AWG) standards, we can calculate the appropriate wire size considering both the current capacity (ampacity) and the voltage drop. For a 30-ampere load at a distance of 205 feet, referencing tables for the ampacity of copper wiring and calculating the voltage drop, determines that a 3 AWG copper wire is suitable. This gauge can effectively handle the load without exceeding the acceptable voltage drop.

Thus, for the specified distance and load, 3 AWG is the wire size that meets both