Distribution line completion inspection in Korea covers the testing, pre-use inspection, charging and energization, and completion inspection needed to close out a distribution project. Distribution lines run close to roads and buildings, so conductor height and sag, clearances to structures and trees, and circuit checks on underground switches are at the center of inspection. This guide covers four stages.
Contents
- Common Pre-Work Review
- 1. Testing and Measurement
- 2. Pre-Use Inspection
- Pre-Use Inspection Items and Evidence (Distribution)
- 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 distribution 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 conductor height, sag and distance between supports against the sag and height 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.
A pre-use inspection request needs the application, a copy of the construction plan approval, a copy of the safety manager appointment and the supervisor deployment confirmation.
Pre-Use Inspection Items and Evidence (Distribution)
| Item | Evidence |
|---|---|
| Conductor height, sag, support spacing | Sag and height records |
| Clearances to conductors, structures, trees | Sag and height records; checklist |
| Insulator strings and clearances | Insulation clearance records |
| Security works | General specification; line checklist |
| Buried earth conductors and resistance | Earth resistance records |
| Dielectric, breakers, charging and load tests | KEPCO / KESCO criteria; test records |
3. Charging and Energization
- After passing the pre-use inspection, establish communication with the distribution 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
Does the completion inspection come before or after the pre-use inspection?
Either, depending on the schedule. It is carried out by the non-resident supervisor with KEPCO present.
Which pre-use items get the most attention on distribution lines?
Conductor height and sag, clearances to structures and trees, insulator clearances, earth resistance, dielectric strength and charging and load tests.
What happens if defects appear after completion?
Based on the defect liability bond submitted at completion, repair measures are prepared where the client considers them necessary.
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 Distribution Line Completion Inspection (배전공사 준공검사, 1901070235_22v3; NCS is Korea’s National Competency Standards) — ncs.go.kr
Summary
The most common mistakes in distribution completion are producing sag, height and clearance records only just before the pre-use inspection, and skipping the switch circuit re-check before energizing underground sections. Build records by trade, agree energization with the distribution center, and prepare the defect liability bond and handover documents together. For pre-construction preparation, see Distribution Line Construction Planning. A Korean version of this guide is available here.
This article restructures the Korean NCS competency unit ‘Distribution Line Completion Inspection’ (배전공사 준공검사, code 1901070235_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