Ace Your Airwaves: 2026 Amateur Radio Operator Exam – Tune In and Rule the Waves!

To understand why the wire gauge that corresponds to a voltage drop limit of 0.05 V per meter at 22 amperes is correct, it is essential to consider both the resistance properties of the wire and the acceptable voltage drop for practical applications.

Copper wire resistance is measured in ohms per unit length. As the wire gauge number decreases, the diameter of the wire increases, which in turn lowers the resistance and, consequently, the voltage drop over a given distance. For a specific current, such as 22 amperes, a wire gauge that can maintain a voltage drop within the specified limit must have sufficiently low resistance.

In this case, Number 8 gauge wire is known for having a lower resistance compared to larger gauge numbers (for example, Number 10 or 12). This characteristic means that at a load of 22 amperes, Number 8 gauge will produce less voltage drop than a higher gauge number wire which has more resistance. Therefore, the calculated voltage drop of 0.05 V per meter remains within acceptable limits for Number 8 gauge wire when carrying 22 amps.

Using a higher gauge wire, such as Number 10 or Number 12, would result in a voltage drop that exceeds the limit of 0.