Because of economic factors, primary distribution is carried out by 3-phase, 3-wire system. The primary distribution circuit delivers power to various substations referred to as distribution. The simplest primary distribution system consists of independent feeders with each customer connected to a single feeder. Since there are no feeder interconnections, a fault will interrupt all downstream customers until it is repaired. 3-phase 4-wire (3PH-4W): Phases A, B, C, and neutral as current-carrying conductors. The common configuration typically involves three key points: the live, neutral, and ground. Make sure these are clearly labeled for ease of installation.