Structural grounding on Korean substations covers bonding the building and its steel and reinforcement into the earthing system and measuring earth resistance so the substation can run safely. A substation building is itself a large mass of conductive material; if it is not firmly tied to the mesh grid, fault currents or surges create potential differences inside and outside the building. Much of this work is buried with the structure, so timing and joint quality matter. This guide covers three stages: planning, installation and earth resistance measurement.
Contents
- Common Pre-Work Review
- 1. Planning
- 2. Installation
- NCS Structural Grounding Points
- 3. Earth Resistance Measurement
- FAQ
- Reference Standards
- Summary
Common Pre-Work Review
Review the design (including architectural, mechanical and structural drawings), schedule, building services rules, KEC, standard electrical specifications and design criteria, KESCO inspection criteria and KOSHA guides on earth conductors and earthing design. Prepare an earth resistance tester, cable cutter and hydraulic compression tool, plus bare stranded copper, earth sleeves, lugs, exothermic welding kit, water barrier rods and earth terminal boxes. Store earthing materials so they are not crushed, deformed or corroded.
1. Planning
- Work out a structural earthing method that suits site conditions.
- Compare the structural earthing calculation and drawings against that method.
- Prepare the structural earthing plan following the method statement guidelines.
- Review earth terminal box and auxiliary electrode positions, and confirm links to the mesh grid and equipment earthing.
2. Installation
- Prepare to install the earthing system to suit the site.
- Connect conductors, rods, the mesh and steel structures fully, electrically and mechanically, per the design and standard procedure.
- Remove any coating or paint from contact surfaces before connecting.
- Allow for galvanic corrosion when joining dissimilar metals.
- Fit waterproof sleeves where conductors from the main grid enter buildings, and use water barrier rods to stop water tracking along conductors into the building.
- Bury conductors below the local frost depth.
- Label earth conductors and auxiliary electrodes.
- Visually inspect that the work follows the specified method.
NCS Structural Grounding Points
| Item | Criterion |
|---|---|
| Contact surfaces | Remove all coating and paint before connecting |
| Dissimilar metals | Allow for galvanic corrosion |
| Building entries | Waterproof sleeves |
| Water ingress | Water barrier rods |
| Burial depth | Below local frost depth |
| Labeling | Label earth conductors and auxiliary electrodes |
| Joint quality | Full electrical and mechanical connection, then visual check |
These values come from the considerations in the NCS competency unit. Target earth resistance follows the earthing calculation and client design standards.
3. Earth Resistance Measurement
- Measure earth resistance after installation and keep records.
- Analyze the results and check for problems.
- If needed, plan reinforcement or improvements to the earthing method.
FAQ
Why earth the building structure?
Bonding steel and rebar into the earthing system reduces potential differences inside and outside the building during faults or surges, protecting people and equipment.
What does a water barrier rod do?
It stops water outside the building from tracking along earth conductors into the building, used with waterproof sleeves at entries.
What should I watch when joining dissimilar metals?
Directly joining metals such as copper and steel can cause galvanic corrosion, so choose joint methods and materials to limit it.
Reference Standards
- Electricity Business Act (전기사업법) — law.go.kr
- Electrical Safety Management Act (전기안전관리법) — law.go.kr
- Electric Technology Management Act (전력기술관리법) — law.go.kr
- Electrical Construction Business Act (전기공사업법) — law.go.kr
- Occupational Safety and Health Act (산업안전보건법) — law.go.kr
- Korea Electro-technical Code (KEC, 한국전기설비규정) — law.go.kr
- Technical Standards for Electrical Equipment (전기설비기술기준) — law.go.kr
- KEPCO design standards and substation construction practice; Korean Industrial Standards (KS)
- NCS competency unit Substation Structural Grounding (구조체접지공사, 1901070325_22v2; NCS is Korea’s National Competency Standards) — ncs.go.kr
Summary
The most common mistakes are connecting without removing coatings and forgetting waterproofing and water barriers at building entries. Planning depends on a site-suited method and calculation review; installation on full joints, dissimilar metals, waterproofing and labeling; and measurement on records and reinforcement plans. Related guides: Substation Mesh Grounding, Substation Equipment Grounding, Substation Ancillary Facilities. A Korean version of this guide is available here.
This article restructures the Korean NCS competency unit ‘Substation Structural Grounding’ (구조체접지공사, code 1901070325_22v2) as a practical reference. Actual work must follow applicable standards and the judgment of qualified professionals; always confirm specific values, deadlines and criteria against the latest regulations and client standards.
Written/reviewed by VOLT · Last updated 2026-10-26