Are AC wire sizes determined by ampacity or voltage drop according to ABYC?

AC wire sizes are primarily determined by ampacity, which refers to the maximum amount of electrical current a conductor or wire can carry before sustaining immediate or future damage. The American Boat and Yacht Council (ABYC) emphasizes that using the correct wire size according to ampacity is critical for ensuring safety, preventing overheating, and mitigating the risk of potential fire hazards.

While voltage drop can also be a consideration in electrical system design, it generally comes into play after ensuring that the wire size is adequate for the expected current load based on ampacity. If the wire size is too small, it may not adequately handle the current, leading to excessive heat and potential hazards. Therefore, since ampacity deals directly with the wire's ability to safely conduct electrical current, it is the central factor in determining wire size.

Voltage drop calculations are taken into account mainly for long runs to ensure that sufficient voltage reaches the end device, but they do not replace the necessity of following ampacity guidelines when selecting wire sizes.