- 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. The following is a detailed introduction to it: - **Familiarize with Drawings**: Carefully study relevant drawing materials such as electrical schematic. secondary unit substation is a close-coupled assembly consisting of enclosed primary high voltage equipment, three-phase power transformers, and enclosed secondary low-voltage equipment. The exposed laying can take the sheath line, or through the pipe and trunking. The concealed laying is mostly through the pipe and. This document shows the methods and requirements for installing PG&E-owned underground service conductors in commercial buildings and three-phase multi-residential buildings. Given their ubiquity, let's delve into the installation and wiring of indoor distribution boxes today.
