A dotted line between components on a three-phase schematic usually indicates?

• A. Ground path between devices
• B. Shielding around conductors
• C. Mechanical interconnection between devices
• D. Independent electrical isolation

Answer: (D)

Dotted lines on a schematic indicate a mechanical interconnection between components rather than an electrical path. They show that two parts move together or are actuated by the same mechanism—like a relay coil and its contacts—so the line communicates a physical linkage, not a voltage or current connection. This is different from a ground path, which uses earth symbols or specific conductor connections; shielding around conductors is typically shown with lines around the cable or a shield symbol; and electrical isolation is represented by keeping components separate or showing an isolation boundary rather than linking them with a dotted line.