The grounding system is the most overlooked part of electrical engineering, yet it causes the most severe accidents when it fails. Many cabinets are "grounded" but fail acceptance tests—problems are hidden in the details.

Grounding electrodes are divided into natural (building steel, metal pipes) and artificial (vertical angle steel, horizontal flat steel).

• Artificial vertical angle steel specification: L50*50*5mm, length ≥2.5m
• Installation depth: Top ≥0.6m below ground level, spacing ≥5m when multiple are connected in parallel
• Measured grounding resistance after construction: ≤4Ω for TN/TT systems, ≤10Ω for repeated grounding

Relationship between PE line cross-section and phase line cross-section (GB 16895):

• Phase line ≤16mm² → PE line = phase line cross-section
• Phase line 16~35mm² → PE line ≥16mm²
• Phase line >35mm² → PE line ≥ 1/2 of phase line cross-section

Using thinner wires to save material is a serious mistake—insufficient cross-section will definitely result in rejection during acceptance.

A dedicated PE busbar must be installed inside the cabinet, and all equipment enclosures, cabinet bodies, and door panels must be individually grounded.

Cabinet door grounding uses yellow-green flexible copper wire ≥4mm² with grounding spring clips—hinge conduction alone is not acceptable.

Fixing bolts between the PE busbar and cabinet body must be rust-proofed, with contact resistance ≤0.1Ω.

All metal pipes, cable trays, and structural steel within the building must be connected to the Main Equipotential Bonding (MEB).

Special locations such as bathrooms and swimming pools must have Local Equipotential Bonding (LEB).

Equipotential bonding conductor cross-section: Copper wire ≥6mm², identified with yellow-green color.

A solid grounding system is the true foundation of electrical safety.