Rapid Identification of Wires in Distribution Cabinets

The core principle for rapid identification of wires in distribution cabinets is as follows: conduct an initial judgment according to standard color codes + numbering rules first, then verify with tools, and finally confirm by combining drawings and terminal blocks, while ensuring proper safety protection and record archiving.

1. Prerequisites and Safety Protection (Mandatory Implementation)
2.  Power-off, voltage testing and tagging: Implement the five-step procedure of “power-off → voltage testing → grounding wire installation → warning sign hanging → barrier erection”. For voltage testing, prioritize dual verification using the voltage range of a multimeter plus a voltage tester. It is strictly prohibited to plug/unplug wire cores or forcibly strip insulation layers while the power is on.
3.  Essential tools: Multimeter (with buzzer function), clamp meter, cable identifier (high-frequency/pulse type, e.g., Fluke 2042), thermal imager (for auxiliary detection of overloaded wires), label printer, cable ties, drawing bag (including primary/secondary schematic diagrams, terminal block diagrams, and cable lists).
4.  Personnel qualification: Certified electricians must wear insulating gloves, insulating shoes and goggles. Working alone is strictly forbidden.
5. Core Identification Methods (Prioritized)Distribution Cabinetswires

(1) Rapid Initial Judgment Based on National Standard Color Codes (Basic, Tool-Free Operation)

(2) Precise Positioning Based on Numbering and Labeling Rules (Drawing-Site Corresponding)

1.  Numbering Format (Industry Universal)

Primary wires (main circuits): e.g., W1 (main incoming line), W11 (main circuit of No.1 motor), W22 (main circuit of No.2 motor); busbar labeling: A/B/C/N/PE.

Secondary wires (control circuits): Numbered by functional zones, e.g., Series 100 (control power supply), Series 200 (No.1 motor control), Series 300 (No.2 motor control), Series 400 (protection circuit); terminal block numbering: e.g., XT1:1 (No.1 terminal of Terminal Block 1), XT2:5 (No.5 terminal of Terminal Block 2).

Cable numbering: e.g., YJV-3×16+1×10-W11 (cable modelspecificationcircuit number).

2.  Identification Steps:

Locate the terminal block (on the right side/bottom inside the cabinet with numbered nameplates) and check the numbers against the terminal block diagram in the drawings.

Use a label printer to supplement missing labels; attach labels 10 cm away from the terminals to avoid covering wire cores.

For cross-cabinet cables, verify that the terminal numbers at both ends are consistent (e.g., XT1:10 corresponds to XT2:10).

(3) Tool Verification (Mandatory Step When Color Codes/Numbers Are Abnormal)

(4) Auxiliary Identification Combined with Cabinet Structure and Circuit Functions

1.  Cabinet Zone Identification:

Upper part: Main incoming switch (molded case circuit breaker, e.g., Schneider NSX100F) → busbars (Yellow/Green/Red/N/PE).

Middle part: Feeder switches (miniature circuit breakers, e.g., Chint NXB-63), contactors (e.g., LC1D32), relays (e.g., RXMH2P)—a dense area of secondary wires.

Lower part: Terminal blocks, earthing bars, cable inlet/outlet ports.

2.  Functional Circuit Identification:

Main circuits: Thick wire diameters (e.g., 16mm², 35mm²), connected to main contacts of circuit breakers and main terminals of contactors.

Control circuits: Thin wire diameters (e.g., 1.5mm², 2.5mm²), connected to contactor coils, buttons and relay contacts.

Protection circuits: Connected to thermal overload relays (e.g., LR-D32), fuses (e.g., RT18-32) and residual current circuit breakers (e.g., DZ47LE).

III. Rapid Identification Process (Direct On-Site Implementation)

1.  Safety Preparation: Power off, test voltage, hang warning signs, wear protective equipment, and prepare tools and drawings.
2.  Color Code Initial Screening: Distinguish three-phase lines, N lines and PE lines by yellow/green/red/light blue/yellow-green dual colors, and mark wires with abnormal colors.
3.  Number Verification: Check wire numbers against terminal block diagrams and cable lists, and supplement missing labels.
4.  Tool Verification: For wires with abnormal color codes/numbers, use a multimeter/cable identifier to confirm continuity and circuits.
5.  Function Confirmation: Confirm wire core applications (e.g., main circuit, control circuit, protection circuit) by combining cabinet zones and circuit functions.
6.  Record Archiving: Take photos of the cabinet, update the cable list, and label the identification results.
7. Common Abnormalities and Solutions

1. Advanced Tips (Improving Identification Efficiency)
2.  Establish a “wire numberfunctionterminal” correspondence table and paste it on the inner door panel of the cabinet for convenient future maintenance.
3.  For secondary circuits, group them by function (e.g., control power supply group, motor forward/reverse group, protection group) and bind them with cable ties of different colors.
4.  During new cabinet design, route wires in advance according to national standard color codes and numbering rules, and print labels simultaneously to avoid rework later.
5.  During the renovation of old cabinets, prioritize replacing wires with mixed color codes, supplement labels, and then carry out other renovation work.
6. Brand/Standard Supplement

– National Standard: GB/T 4026-2019 Basic Safety Principles for Signs and Identification of Operation Parts of Human-Machine Interfaces—Colors of Indicators and Operation Parts

– International Standards: IEC 60309, IEC 60204

– Mainstream cabinet manufacturers (Schneider, Chint, ABB) all follow national standard color codes. The numbering of secondary wires can be adjusted according to manufacturer drawings, but must be consistent with terminal block diagrams.