Transmission line completion inspection in Korea covers the testing, pre-use inspection, charging and energization, and completion inspection needed to close out a transmission project. Transmission lines center on towers and long spans, so visual items such as sag, ground clearance, span length and tower assembly and painting make up much of the inspection, and communication with the transmission control center is key at energization. This guide covers four stages.
Contents
- Common Pre-Work Review
- 1. Testing and Measurement
- 2. Pre-Use Inspection
- Key Pre-Use Inspection Items (Transmission)
- 3. Charging and Energization
- 4. Completion Inspection
- FAQ
- Reference Standards
- Summary
Common Pre-Work Review
First confirm KEPCO quality regulations, the approved quality test plan, the construction specifications and the KEC and Electrical Safety Management Act. Prepare a compression tester, dielectric strength tester and protective relay tester, plus a gas analyzer, earth resistance tester, insulation tester, multimeter, discharge device and phase meter, along with tension calculation software, camera, radios and a voltage detector. Workers wear hard hats, safety vests, safety shoes and harnesses and carry lanterns.
1. Testing and Measurement
- Carry out stage tests on the transmission line with the client present, following KEPCO quality regulations and the approved test plan.
- For foundations, carry out concrete, soil and material tests at mandatory hold points.
- For superstructure work, carry out quality tests by measurement for every trade.
- During each trade’s work, test visually or with instruments.
- Inspect spacers and conductor joints (sleeves) against the compression joint records.
2. Pre-Use Inspection
- Inspect ground clearance, sag and span length against the sag and ground clearance records.
- Inspect clearances between conductors and to structures and trees using the records and checklist.
- Inspect insulator string assembly, inclination and insulation clearance between protective devices and supports.
- Inspect security works against the general specification and line checklist.
- Inspect buried earth conductors and earth resistance against the earth resistance records.
- Apply test voltage to the line to inspect dielectric strength to KEPCO or Korea Electrical Safety Corporation criteria.
- Test power circuit breakers and protective relays using the substation line breaker.
- Carry out line charging and load tests to KEPCO or Korea Electrical Safety Corporation criteria.
- Confirm compliance with the KEC and the Electrical Safety Management Act.
- Inspect control, metering and protective devices against test records and protection criteria.
- Confirm alarms operate immediately when a fault is detected.
When the pre-use inspection is requested, the Korea Electrical Safety Corporation first carries out visual inspection — tower foundations, site restoration, tower assembly, stringing and sagging, fittings and attachments, painting, phase rotation and loop tests.
Key Pre-Use Inspection Items (Transmission)
| Area | Items | Evidence |
|---|---|---|
| Tower visuals | Foundations, site restoration, assembly, painting, attachments | Visual inspection checklist |
| Conductors | Sag, ground clearance, spans, clearances | Sag and ground clearance records |
| Insulation | String assembly, inclination, clearances | Insulation clearance records |
| Earthing | Buried earth conductors, earth resistance | Earth resistance records |
| Electrical tests | Dielectric, breakers and relays, charging and load, phase rotation and loop | Test records |
3. Charging and Energization
- After passing the pre-use inspection, establish communication with the transmission control center before energizing.
- After inspecting overhead and underground lines, carry out no-load and on-load charging, then energize.
- Re-check the line between switch terminals before energizing underground lines to prevent wrong-circuit errors.
- Confirm phases before closing the switch, then connect to other lines.
4. Completion Inspection
- Decide whether the completion inspection comes before or after the pre-use inspection, according to the schedule.
- Prepare the completion inspection documents and the defect liability bond.
- Identify failed items, rework them and request re-inspection.
- Prepare documents (O&M manual, long-term repair plan) so the supervisor can hand the facility over to the client.
- If the client disagrees on handover, propose and implement measures.
- After completion, prepare defect repair measures where the client considers them necessary.
The completion inspection is always carried out by the non-resident supervisor with KEPCO present. It checks construction against the design documents, resident supervisor records, waste disposal, use of client-furnished materials and handling of surplus, removal of temporary works and site restoration, and the supervisor’s review opinion.
FAQ
What does the visual inspection cover for transmission lines?
Tower foundations, site restoration, tower assembly and painting, stringing and sagging, fittings and attachments, together with phase rotation and loop tests.
Why do sag and ground clearance matter?
They set the safe distance between conductors and the ground, structures and trees, confirmed span by span from measurement records.
What is prepared before energizing a transmission line?
After passing the pre-use inspection, communication with the transmission control center, the charging sequence and the phase-check procedure.
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
- KEPCO design standards; field practice manuals for transmission and distribution work; Korean Industrial Standards (KS)
- NCS competency unit Transmission Line Completion Inspection (송전공사 준공검사, 1901070236_22v3; NCS is Korea’s National Competency Standards) — ncs.go.kr
Summary
The most common mistake in transmission completion is failing to organize sag, ground clearance and tower visual records by trade, forcing re-measurement during the pre-use inspection. Keep test records for every trade, agree energization steps with the transmission control center in advance, and prepare handover documents alongside the completion inspection. For pre-construction preparation, see Transmission Line Construction Planning. A Korean version of this guide is available here.
This article restructures the Korean NCS competency unit ‘Transmission Line Completion Inspection’ (송전공사 준공검사, code 1901070236_22v3) 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 2026-10-25