Electrical Distribution One-Line Diagram Study Guide

A one-line diagram compresses a power-distribution system into a simplified drawing. Learn to follow the represented system from source through transformation and distribution to downstream loads.

Use the drawing type to understand system relationships; a one-line does not show the same detail as a wiring or control schematic.

• Find the source before following downstream equipment.
• Notice where transformers change the represented voltage level.
• Follow feeders and major distribution equipment in sequence.
• Use protective-device position as a system-reading clue.