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Wrong Wiring Colors in Control Cabinet Lead to Rejection on Acceptance?Complete Guide to National Standard Color Codes f

Wrong Wiring Colors in Control Cabinet Lead to Rejection on Acceptance?Complete Guide to National Standard Color Codes f

2026-06-12

Wiring colors for control cabinets are not chosen arbitrarily. Clear regulations are specified in national standards GB/T 6988 and GB 7947. Improper color selection will result in circuit rejection during acceptance at the very least. In severe cases, misjudgment of circuits during maintenance may lead to short circuit accidents.

latest company news about Wrong Wiring Colors in Control Cabinet Lead to Rejection on Acceptance?Complete Guide to National Standard Color Codes f 0

Color Codes for AC Circuits
Circuit Type Standard Color
AC Phase A (L1) Yellow
AC Phase B (L2) Green
AC Phase C (L3) Red
Neutral Line (N) Light Blue
Protective Earth (PE) Green-Yellow Bicolor
Color Codes for DC Circuits
Circuit Type Standard Color
DC Positive (+) Brown
DC Negative (−) Blue
Midpoint Earth (M) Light Blue
Color Codes for Control Circuits
  • AC control circuits: Red
  • DC control circuits: Blue
  • Circuits directly connected to external equipment: Orange
  • Interlock control circuits: Yellow
Three Common Pitfalls to Avoid

The PE wire must adopt green-yellow bicolor. Pure yellow or pure green cannot be used as alternatives.

White is not allowed for the neutral line (N). White is not defined in national standards and will easily cause confusion.

Isolation sections must be reserved between strong-current and weak-current terminal blocks inside the control cabinet, and the color marking shall be consistent all the way.

Wiring color compliance is the fundamental requirement of engineering specifications and a mandatory inspection item for clients during acceptance. Standard wiring reflects professionalism, while non-compliance will only cause time-consuming rework.