The third-level distribution box is typically installed about 1.5 meters (approximately 4.9 feet) above the ground.

In a three-level distribution system, the general arrangement consists of a main distribution box, a secondary distribution box, and a switch or third-level distribution box placed below the secondary box for final circuit control and protection . The recommended height for the third-level box is generally around 1.5 meters from the floor, which ensures it is easily accessible for operation, inspection, and maintenance while remaining safe from accidental contact or environmental hazards .

Installation Considerations

• Accessibility: The height allows users to read labels, operate switches, and perform maintenance without bending or stretching excessively .
• Safety: Keeping the box elevated prevents exposure to water, dirt, or accidental impact, especially in residential or industrial settings .
• Compliance: Following standards such as IEC 60364-5-52 or NEC guidelines ensures proper clearance and safe operation. For example, NEC recommends a dedicated electrical space from the floor up to 1.8 meters for panelboards .
• Environment: Ensure the box is installed in a dry, ventilated area with sufficient clearance around it for airflow and future inspections . By installing the third-level distribution box at approximately 1.5 meters, you achieve a balance between ergonomic access, safety, and compliance with electrical standards, making it suitable for both residential and industrial applications.