1. Grounding Resistance
The grounding system of the box transformer shall exhibit a resistance not exceeding 4 Ω. If a horizontal grounding electrode alone cannot achieve this value, additional vertical electrodes must be installed to ensure adequate grounding performance.
2. Burial Depth
All grounding conductors and electrodes must be buried at a depth of no less than 1 m to maintain safe touch and step voltage levels around the substation.
3. Equipment Enclosure Bonding
Every metal enclosure and base frame of the high‑voltage switchgear, transformer tank, and low‑voltage distribution panels must be solidly bonded to the grounding network to guarantee personnel safety and equipment protection.
4. Transformer and Base‐Frame Grounding
Both the transformer’s support base and the steel base of the box enclosure shall each be connected to the grounding network at a minimum of two distinct points—ideally one at each end of the base—to provide redundant paths and lower overall resistance.
5. Corrosion Protection
All grounding electrodes, conductors, and connectors must receive a hot‑dip galvanizing treatment (or equivalent anti‑corrosion coating) to prevent oxidation and extend service life.
6. Welding and Jointing
Every mechanical joint or lap splice in the grounding system must be welded using a qualified procedure. Lap lengths shall be no less than twice the width of flat conductors (or six times the diameter for round rods) to ensure a reliable, low‑impedance connection.
7. Pedestrian Passageway Treatment
In areas where the grounding network intersects footpaths or service aisles, the surface above electrodes should be finished with crushed stone, concrete, or asphalt paving to prevent accidental contact and to maintain a stable walking surface.
By following these measures—controlling resistance, ensuring adequate burial depth, bonding all metallic parts, protecting against corrosion, and providing solid joints—you will achieve a safe, reliable, and durable grounding installation for your outdoor box‑type substation.