In control cabinets, green-yellow is used for protective earth, light blue for neutral, and other colors like black, red, or blue are used for AC/DC power and control circuits depending on the standard.

Protective Earth and Neutral

• Protective Earth (PE): Always green-and-yellow, reserved exclusively for earth conductors, with a 70/30 stripe distribution over any 15mm length if insulated, or applied at accessible points if wiring is concealed (EN 60204-1, IEC 60445) .
• Neutral (N): Light blue throughout the conductor length, or marked with a 15–100mm stripe if in a concealed location .

AC and DC Power Conductors

• AC main power: Typically black for non-earthed conductors (IEC recommendations) .
• AC control circuits: Often red .
• DC control circuits: Usually blue or dark blue .
• Power chains not requiring separation: Orange may be used for live circuits that remain energized when the main switch is off .

UL 508A Specifics (North America)

• Non-earthed internal main circuit wires: black.
• Grounded AC-carrying conductors: white or gray, or marked with three white stripes if insulation is a different color.
• Protective conductors: green, with or without yellow stripes .
• Minimum wire size for control circuits: 18 AWG, with sizing based on overcurrent protection or power supply ratings .

Additional Notes

• Avoid using green or yellow alone to prevent confusion with protective earth .
• Alternative identification methods such as terminal numbering, wire markers, or functional labels are allowed under IEC 60445 if color coding is not feasible .
• Tri-rated cables (BS 6231) are commonly used in control panels for high-temperature and fire-retardant applications . By following these color conventions, control cabinet wiring remains safe, traceable, and compliant with international standards, while minimizing the risk of misidentification during installation or maintenance.