Wiring diagrams and symbols

When you’re interpreting wiring diagrams, recognizing symbols is key. See those two parallel lines? That’s a common representation of a contactor. Think of a contactor as a heavy-duty, electrically-operated switch—it's used to control high-voltage circuits. These are frequently found in HVAC systems, often working in conjunction with relays. Understanding this symbol is critical, especially when dealing with energized or de-energized circuits, and particularly important in fire life safety applications.