When selecting electric cable size, which criteria is key?

The key criterion when selecting electric cable size is the current carrying capacity and allowable voltage drop.

Current carrying capacity refers to the maximum amount of electrical current a cable can handle safely without overheating. This is crucial for ensuring that the cable does not exceed its thermal limits under normal operating conditions. If a cable is undersized for the current it carries, it can lead to overheating, risk of fire, and eventual failure of the electrical system.

Allowable voltage drop is another significant consideration. As electric power is transmitted through a cable, some energy is lost as heat, leading to a reduction in voltage at the load end. Keeping this voltage drop within acceptable limits is essential for maintaining the performance and efficiency of electrical systems. Excessive voltage drop can result in poor performance of electrical devices, affecting everything from motors to lighting systems.

While applied voltage and insulation type are relevant factors, they do not have the same direct impact on the safety and efficiency of a cable in the same way that current carrying capacity and allowable voltage drop do. Temperature ratings also matter but more in the context of the cable material and installation environment rather than in the sizing process itself.