BY: NIGEL CALDER
Conductors are the arteries of our electrical systems. If undersized, they create resistance to electron flow, causing power losses and heat; in a worst case, sufficient heat to set a boat on fire.
Given stranded copper conductors, which are what we always use in boats, two factors determine the size of the conductors in any given circuit: conductor ampacity and voltage drop.
Ampacity
Whenever a current (amps) is passed through a conductor, some heat is generated. The higher the current in relation to the size (cross-sectional area) of the conductor’s copper core, the more the heat is generated. At some point, the conductor will get hot enough to melt its insulation.
The ampacity of a conductor defines the maximum current in amperes that the conductor can carry on a continuous basis without the insulation approaching its melt down temperature.
For a given cross-sectional area of copper, the ampacity is determined by three factors: the temperature rating of the conductor insulation, the ambient temperature, and whether or not the conductor is in a bundle with other conductors.
