Secondary wiring: used to control, measure, protect, and indicate signals for the primary wiring. of one cabinet (rack) supplied by the Rack Power Distrib nsfer swi ch right before the device that allows in s s doubled. A feeder usually begins with a feeder breaker at the distribution substation. Many feeders leave substation in a concrete ducts and are routed to a nearby pole. The following is a detailed introduction to it: - **Familiarize with Drawings**: Carefully study relevant drawing materials such as electrical schematic. The symbology (low voltage circuit breaker, low-voltage drawout circuit breaker, medium voltage switch, medium voltage breaker) reflects the most commonly-used equipment for each arrangement. The radial system is the simplest system. The main differences between the primary wiring and secondary wiring of the distribution cabinet are as follows: Function Primary wiring: used to realize the transmission, distribution and control of electric energy, directly connected to the power supply and power equipment, responsible for the. - Secondary circuit wiring should meet design requirements, and the insulation wire rating should not be lower than 450/750V except for electronic component circuits; copper core insulated wire or cable conductor cross-section for current circuits should be no less than 2. 5mm², and other circuits.