Distribution Box Labeling Standards

The labeling standards for electrical distribution boxes constitute a rigorous system, primarily based on multiple national industry standards. Its core logic is to ensure the safe operation and efficient maintenance of the power system through standardized text, symbols, and colors. The main requirements are as follows:

I. External Labeling of Electrical Distribution Boxes

1. Warning Sign
Content: A standard yellow triangular "Caution: Electric Shock" warning sign must be affixed. The background is yellow, and the lightning bolt symbol is black.

Location: Affixed to the upper center of the front of the distribution box door or in an easily visible location.

Size: Selected according to the size of the box, generally not less than 10cm × 10cm.

2. Distribution Box Number/Name
The purpose or area to which it belongs must be indicated, such as "Lighting Distribution Box No. 1" or "Elevator Dedicated Distribution Box."

The lettering should be clear and resistant to fading; red or black font is recommended.

3. Responsibility Sign/Contact Information
Indicates the person in charge of management and their contact number.

Commonly found in industrial or public places, facilitating contact in emergencies.

4. Voltage level marking: This can be omitted for 400V/230V low-voltage boxes; for high-voltage boxes, "High Voltage Danger" must be marked in a prominent position.

II. Internal Labeling of Distribution Box

1. Circuit Labeling
Each circuit breaker, fuse, or circuit should be labeled with a unique circuit number, corresponding to the system diagram.

The controlled equipment or area must be clearly indicated, such as "Lighting Circuit L1" or "Water Pump Standby".

Ambiguous labels such as "Unknown" or "To be checked" are strictly prohibited. It is recommended to use a waterproof and heat-resistant label printer.

2. System Circuit Diagram
The system wiring diagram of this distribution box, or a scaled-down version, must be affixed to the inside of the box door.

The diagram should indicate: main switch capacity, circuit numbers, wire diameter, load name, and leakage protection parameters.

Any changes to the diagram must be updated within one week.

3. Neutral (N) and Protective Earth (PE) Labeling
Affix an "N" symbol (light blue) near the N terminal block.

Affix a "PE" symbol or grounding symbol (yellow-green) near the PE terminal block.

III. Switch Status and Operation Indications

1. Switch Status Indication
Larger knife switches or disconnect switches must be clearly marked "Close"/"Open" or "ON"/"OFF" next to the operating handle, and the direction of operation must be clearly stated.

2. Do Not Close Sign
During maintenance, a "Do Not Close, People Working" sign with red background and white lettering should be hung on the main switch or the corresponding circuit switch.

Note: This is a temporary sign, not a permanent affixation.

3. Standby Circuit Sign
Switches that are not connected or not in use must be labeled "Standby" to avoid misinterpreting them as faulty.