Why We Removed Working Electrical Wiring During a Commercial Renovation

Why remove electrical wiring that still works?

It is a reasonable question on any commercial renovation project. Reusing existing circuits appears cheaper, faster, and less wasteful than removing them and starting again.

But during the conversion of a former dental clinic into a studio in South Korea, we reached the opposite conclusion.

On the first floor alone, three electricians could have spent roughly a week tracing, sorting, modifying, and reorganizing the existing branch circuits. Instead, three of us removed the unnecessary wiring in one working day, from approximately 8:00 a.m. to 3:30 p.m., and estimated about four days to rebuild the first-floor electrical system around the new studio layout.

The Wiring Had Not Failed. The Building Had Changed. The real question was not whether the old wiring could still carry power. It was whether the existing electrical system still made technical, practical, and economic sense for the new use of the space.

The project covered two floors, approximately 40 pyeong each (about 132 m² / 1,420 sq ft per floor). The previous dental clinic had received its pre-use electrical inspection around March 2020, so this was not an extremely old installation.

Age was not the main problem. The electrical requirements of a dental clinic and those of the new studio were simply very different.

The former dental clinic after partial interior demolition, with the existing ceiling wiring and conduit system exposed.

1. What We Found After the Interior Demolition

By the time we arrived, the demolition crew had already removed portions of the ceiling and walls. The electrical wiring had mostly been left alone, which is common during interior demolition because unidentified electrical circuits can create both safety and liability problems if they are cut without first being checked.

Once the ceiling was opened, a large amount of existing wiring became visible. Much of the branch-circuit wiring consisted of 2.5 mm² HIV conductors installed in CD flexible plastic conduit.

Some of the existing circuits were still operational. We checked receptacles individually and operated the remaining lighting switches. Where a light fixture had already been removed, a non-contact voltage tester was used at the switch to confirm that voltage was still present.

Numerous existing branch circuits were exposed after the ceiling was partially removed.

Important: This Was Not a Fault-Finding Job We did not perform insulation-resistance testing on the branch circuits because they had already been selected for removal. The wiring was not removed because we had found insulation failure or another electrical fault.

2. Working Wiring Was Not the Same as Useful Wiring

A dental clinic can require many dedicated circuits for equipment such as dental chairs, X-ray systems, and other clinical loads.

The new studio will be much simpler electrically. It will require only a limited number of receptacles and general lighting circuits, although some distinctive studio lighting will be added later.

This meant that much of the existing branch wiring no longer matched the new floor plan or load requirements.

We could have tried to reuse selected circuits, but that would have required identifying each circuit at the distribution panel, tracing its route above the ceiling, determining whether it was still useful, removing the unnecessary circuits, and modifying the remaining wiring to suit the new outlet and lighting locations.

Some of the retained conductors would also have been too short for the new positions, requiring additional extensions and rework.

A non-contact voltage tester confirmed that power was still present at an existing lighting switch even though the fixture had already been removed.

3. Why CD Conduit Became an Issue Under Current Korean Electrical Rules

Another important factor was the extensive use of CD flexible plastic conduit in the concealed ceiling space.

Under current Korean Electrical Code requirements, synthetic-resin conduit cannot be installed within a double ceiling, including the concealed space above a suspended ceiling. The relevant restriction took effect on January 1, 2022.

The background is primarily fire safety. The Korea Electric Association explains that research into major fire causes found that synthetic-resin conduit installed in double-ceiling spaces could contribute to fire spread and the generation of toxic gases. The rule was strengthened to limit these fire-vulnerable wiring methods in concealed ceiling spaces.

Existing Installation vs. New Renovation Work The former dental clinic received its pre-use inspection around March 2020, before the current restriction took effect. Therefore, this article does not claim that the original 2020 installation was illegal. The issue for this project was how the newly renovated studio should be wired under requirements applicable to the new work.

Official KEC guidance also recognizes transitional treatment for installations that were already lawfully established or had received applicable approvals before the new rule took effect. New or expanded installations, however, are generally expected to follow the requirements applicable at the time of the new work.

For international readers, this is specifically a South Korean electrical requirement. Other countries may use different conduit classifications, fire-performance requirements, or permitted wiring methods, so local codes should always be checked.

4. Why Selective Reuse Would Have Taken Longer

This is where the field decision became especially clear.

For the first floor alone, I estimated that three electricians could spend approximately one week tracing, identifying, sorting, removing, and reorganizing the existing circuits if we tried to preserve selected branch wiring.

Even after that effort, circuits that no longer reached the new studio locations would still require modification.

By comparison, we estimated approximately four working days to rebuild the first-floor branch wiring around the new layout after demolition.

The actual removal of the unnecessary existing wiring was completed by three electricians in a single day, from approximately 8:00 a.m. to 3:30 p.m.

The existing dental-clinic branch circuits were removed rather than traced and reorganized for the much simpler electrical requirements of the new studio.

Existing Does Not Automatically Mean Economical Reusing existing wiring can save labor when the circuits are clearly identified and still suit the new layout. But when the new occupancy needs far fewer circuits, tracing and modifying a complicated old system can cost more labor than removing it and installing only what is actually needed.

5. We Did Not Remove Everything

The decision was not simply to remove every existing electrical component. We retained the parts that still made practical sense for the new studio.

Air-Conditioning Feeder

The existing air-conditioning feeder was installed with CV cable, and the outdoor-unit location was expected to remain usable. There was no practical reason to remove that feeder simply because other branch circuits were being replaced.

Exterior Sign Circuit

The sign circuit was also retained. Because it runs toward the exterior of the building, removing it unnecessarily could make reconnection more difficult later.

Distribution Panels

The existing distribution panels were also retained at this stage. Each floor has a 4-pole 40 A main breaker, and our initial visual inspection did not reveal obvious signs that required immediate replacement.

The panels have not yet undergone the final inspection for the new studio installation, so reuse remains subject to the checks performed as the project progresses.

Before and after removal of unnecessary branch-circuit wiring. The distribution panel itself was retained for further inspection and planned reuse.

6. How the New Studio Wiring Will Be Installed

The next stage will begin after coordination with the interior contractor. We first need the final positions of the lighting fixtures, switches, receptacles, and any specialized studio lighting.

The new branch wiring will then be installed using an appropriate metallic flexible-conduit method for the site conditions, with HFIX conductors. The exact conduit type and installation method will be selected to suit the location and applicable requirements.

KEC guidance permits metallic flexible-conduit wiring methods in applicable concealed spaces, but the permitted type can vary according to whether the location is accessible, concealed, wet, or otherwise subject to specific conditions.

Access panels will be planned strategically rather than scattered unnecessarily throughout the ceiling. One will generally be located near the distribution panel, with additional access near ceiling-mounted air-conditioning equipment where useful.

Because the ceiling void is relatively narrow and the new studio does not require a large number of circuits, a cable-tray system would add cost and installation difficulty without offering much practical benefit here.

New Design Principle Install only the circuits the new studio actually needs, use wiring methods appropriate for the current renovation, and keep important concealed areas reasonably accessible for future inspection and maintenance.

7. Reuse or Replace? Our Field Decision

Good renovation work is not about preserving as much old wiring as possible, nor is it about replacing everything automatically. Each part of the installation should be judged by whether it still makes sense for the new occupancy.

Existing Condition

Field Decision

Dental branch circuits in CD conduit

Remove. The circuit arrangement no longer matched the studio, and the new ceiling work would be designed around current requirements.

Unknown or unnecessary branch circuits

Remove. Circuit tracing and modification would consume more labor than the new studio layout justified.

Air-conditioning CV feeder

Retain. The feeder and outdoor-unit location remained practical for the new use.

Exterior sign circuit

Retain. Removing an existing route to the exterior would make later reconnection unnecessarily difficult.

Existing distribution panels

Retain for now. No obvious abnormal condition was found visually, but final reuse remains subject to further inspection.

New studio lighting and receptacles

Install for the new layout. Only the circuits actually required by the studio will be rebuilt.

8. “But It Still Works. Why Replace It?”

If the lights turn on and the outlets still work, it is natural to assume that keeping the existing wiring must be cheaper.

Sometimes that is true.

If existing circuits are clearly identified, installed in a suitable manner, located where the new loads need them, and in appropriate condition, selective reuse can be entirely reasonable.

This site was different. The system had been designed for a dental clinic with many more branch circuits than the new studio required. Much of the routing was no longer useful, circuit identification would require substantial labor, and the renovated concealed wiring needed to be planned according to current requirements.

For electrical work that can directly affect fire and personal safety, code compliance is not something we treat as a negotiable convenience. The responsibility attached to an electrical accident can be far greater than the small amount of material that might initially appear to be saved.

Working Wiring Is Not Necessarily Reusable Wiring. The correct question is not only whether the old circuit still works, but whether it remains suitable for the new use of the building.

9. Field Takeaway

This project shows why commercial electrical renovation cannot be reduced to a simple choice between “reuse everything” and “replace everything.”

We removed the branch circuits that no longer suited the new studio, retained the air-conditioning feeder and exterior sign circuit where reuse still made practical sense, and kept the existing distribution panels for further inspection.

The next installation will be built around the actual lighting, receptacle, and studio-equipment requirements rather than around the electrical layout of the former dental clinic.

That is the real objective of renovation electrical work: not to preserve the most wiring and not to replace the most wiring, but to build the electrical system that makes sense for what the space is becoming.

After the unnecessary branch circuits were removed, the site was ready for a new electrical layout designed specifically for the studio.

Electric Korea Korean Electrical Construction · Field Experience · Safety · Technical Education
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