Distribution box terminals are represented by standardized symbols indicating connection type, polarity, and function according to IEC 60617 and other electrical standards.

Common Terminal Symbols

• Terminal / Terminal Block: Represented as a small rectangle or circle with screw or connection marks, indicating where wires connect to a device or component (IEC 60617) .
• T-Connection / Junction: A T-shaped symbol showing a wire branching to another conductor, used for signal or power distribution .
• Double Junction: Two conductors joined at a single point, often used for multiple signal connections .
• Plug and Socket: Male and female contacts are shown as circles or rectangles with lines indicating connection type; multipole connectors may be represented with multiple lines .
• Connecting Link: Symbols for closed or open links, sometimes shown as U-shaped lines, indicate temporary or permanent bridging between terminals .
• Cable Sealing End / Gland: Represented for multi-core or single-core cables entering a distribution box, ensuring proper insulation and protection .
• Junction Box / Connection Box: A square or rectangle symbol representing the enclosure where multiple terminals are housed .

Signal and Power Indicators

• Positive / Negative Polarity: Symbols like “+” and “−” indicate DC connections .
• Neutral / Protective Conductor: Neutral is often marked with “N” and protective earth with “PE” or a specific grounding symbol .
• 3-Phase Connections: Represented with three lines, sometimes with neutral and protective conductors indicated separately .
• Wiring Direction: Arrows on lines indicate whether wiring goes upward or downward in the schematic .

Additional Notes

• Signal Terminals: May include designations for analog or digital signals, often annotated with letters or numbers to indicate input/output type .
• Protective Devices: Symbols for fuses, circuit breakers, or surge protection may be integrated near terminals to indicate safety measures .
• Legend and Documentation: Always refer to the schematic legend or manufacturer documentation, as symbols can vary slightly depending on the drawing standard or software used . Understanding these symbols ensures correct wiring, safe operation, and compliance with electrical standards when working with distribution boxes.