What is a one-line diagram used for?

• A. It lists all device model numbers.
• B. It provides detailed wiring color codes.
• C. It shows the electrical distribution system and connections in a simplified form for planning and installation.
• D. It demonstrates the exact physical routing of each wire.

Answer: (C)

A one-line diagram communicates the electrical distribution system and connections in a simplified form for planning and installation. It uses a single line to represent conductors and shows how power flows from the source through feeders and distribution panels to loads, along with the protective devices that control each path. This helps you quickly understand the system’s topology, plan changes or expansions, and ensure correct interconnections during construction. It’s not intended to show exact wire routes or every device model or wiring color detail—that level of detail belongs to more detailed drawings or specifications—so the diagram stays focused on how the system is connected and how power moves through it.