The primary distribution box refers to the main distribution box, typically located in the distribution room. Secondary distribution grid: This. The electricity supply chain consists of three primary segments: generation, where electricity is produced; transmission, which moves power over long distances via high-voltage power lines; and distribution, which moves power over shorter distances to end users (homes, businesses, industrial sites. Understanding the fundamental distinction between Primary and Secondary distribution in electrical systems is pivotal for designing efficient and reliable electrical distribution systems tailored to specific needs across various domains.