What does a medium-voltage electrical contractor do, and how is it different from a low-voltage contractor?
A medium-voltage (MV) electrical contractor designs, supplies, installs, tests and energizes installations above 1 kV and, under Turkish regulations, up to 36 kV: transformer substations, MV switchgear, MV cable lines and distribution centers. Compared with low-voltage work, it involves far higher fault energy, mandatory utility approval and acceptance, and specialist testing and operating competence.
Checklist for the contractor's scope:
1. Has the contractor delivered work at your voltage level and facility type (substation, factory, organized industrial zone, solar, wind)?
2. Which of design, panel manufacturing, installation and testing does it perform in-house?
3. Will it take responsibility through utility acceptance and energization?
4. Does it provide maintenance and fault support after commissioning?
On low-voltage work, a mistake usually ends with a tripped protective device. In an MV installation, a poor cable termination, a wrong protection setting or incomplete grounding can endanger lives and leave a facility without power for a long time.
MV installations also pass through the distribution company's or another authority's approval process from design to acceptance. Choosing an MV contractor is therefore less about hiring an installation crew and more about choosing a single point of contact able to manage engineering, manufacturing and site work together.
How do you verify a contractor's authorization documents, professional chamber registrations and ISO/TSE certificates?
Verify documents against the issuing body's records, not the contractor's copies. The full legal name and registration can be checked in the Turkish Trade Registry Gazette, chamber membership with the relevant chamber of commerce and industry, ISO certificates in the certification body's online register, and the TSE HYB certificate through the Turkish Standards Institution's certificate inquiry service.
Checklist for verifying documents:
1. Does the legal name on each certificate exactly match the entity you will sign with?
2. Are the ISO 9001, ISO 14001 and ISO 45001 certificates valid, and does their scope cover electrical contracting and installation?
3. Is the certification body accredited?
4. Are the engineers who will sign drawings registered with the Chamber of Electrical Engineers (EMO), and do they hold the relevant professional authorizations?
5. Does the TSE HYB (Service Competence Certificate) cover the service you are buying?
Where several firms trade under similar names, a brand name alone can mislead, so put the tax number, MERSİS (central registry) number and full legal name into the contract draft.
ISO 45001 deserves particular attention on MV work, where crews operate near energized equipment, because it shows that occupational health and safety is managed systematically. A certificate alone is not enough, though: see how it is applied during a site visit. If your project team works in English, also confirm that reports and correspondence can be delivered in English.
How should references and completed projects be evaluated, and which questions should you ask the contractor?
How closely past projects resemble yours matters more than the length of the reference list. Check the voltage level, facility type, scale, the scope the contractor actually delivered and whether the project was completed through acceptance. Where possible, speak directly with the reference client and visit an active site.
Questions to ask the contractor:
1. Were you the main contractor or a subcontractor on this project, and what was your scope?
2. What voltage level and transformer rating did it involve?
3. Was provisional acceptance granted, and how quickly were the deficiencies closed?
4. Will the site manager and technical team from that project work on ours?
5. Can we speak with the client's representative?
6. How many active sites do you run today, and which resources will be assigned to our project?
Cumulative figures such as total projects, installed transformer capacity or cable length show a contractor's scale, and it is fair to ask how they are calculated. Repeat work with the same client is as telling as the names on the list.
The number of active sites helps you judge capacity and the crew and equipment the contractor can actually commit to your project.
Why do an in-house site team, test equipment and panel manufacturing capacity matter?
A contractor with its own site crews, test equipment and panel workshop controls quality and schedule directly. When most of the work is subcontracted, responsibility fragments; when test equipment is rented or panels are bought in, the risk of delays and interface errors rises.
Checklist for in-house capacity:
1. Do the technicians who make MV cable terminations and joints hold manufacturer training certificates?
2. Does the contractor own its VLF and tan delta test sets, high-voltage insulation testers, earth resistance testers, protection relay test sets and thermal cameras, with current calibration certificates?
3. Are panels built in its own workshop and routine-verified under IEC 61439?
4. Can it document experience installing and commissioning MV switchgear?
A contractor that manufactures its own panels can apply design revisions in the workshop quickly and works from the same documentation as the site crew. Owning test equipment means tests can be run, and repeated when needed, without waiting on rental availability.
A permanent site team keeps the same people accountable from start to finish, and that continuity is what closes deficiencies quickly during acceptance.
How do you check a contractor's experience with project approval, DSO acceptance and energization?
Check a contractor's approval, acceptance and energization experience through evidence: designs it has taken through approval, acceptance files it has prepared and energizations it has led. On MV installations, design approval, provisional acceptance and energization drive the schedule as much as site work does, and a contractor that cannot manage them may finish the installation yet still leave the facility without power.
Checklist for approval, acceptance and energization:
1. Which authorities approved and accepted its work: regional distribution system operators (DSOs, known as EDAŞ in Türkiye), TEDAŞ (Turkish Electricity Distribution Corporation, the state-owned owner of distribution assets that takes part in acceptance), organized industrial zones or other bodies?
2. Is a sample acceptance file complete, with test reports, grounding measurements, as-built drawings and equipment documents?
3. How quickly were the deficiencies found by the acceptance committee closed?
4. Who coordinates with the DSO on energization day?
5. Who calculates and applies protection coordination and relay settings?
The most common causes of acceptance delays are missing or inconsistent test reports, site work that departs from the approved design, and grounding measurements that miss the limit values. When design and site teams work under one roof, the approved design and the installation stay aligned.
Who takes over operating responsibility after energization, including the requirement for an authorized operations engineer (işletme sorumlusu) for the installation, should also be settled at contract stage.
When comparing bids, how do you level the scope, and why is price alone risky?
Bids are only comparable when they are priced on the same bill of quantities, the same technical specification and the same inclusions and exclusions. Price alone is risky because the lowest bid often hides missing scope, lower-specification materials or items that return later as variation orders.
Checklist for comparing bids:
1. Are equipment brands and technical specifications stated in the bid?
2. Who carries civil works, excavation and kiosk foundations?
3. Are testing, acceptance fees and energization coordination included?
4. Does the bid include delivery of as-built drawings and documentation?
5. Are the program and payment schedule defined?
6. What is the warranty period, and is post-commissioning support included?
7. Which unit rates will price additional work?
The most practical way to level scope is to commission an independent site survey and quantity takeoff before tendering, or to ask every bidder for unit-rate pricing in the same format. Each bidder's inclusions then show up line by line, and negotiation moves from price to scope.
How does Miratek Elektrik meet these criteria?
Miratek Elektrik meets these criteria by running design, panel manufacturing, site installation, testing and commissioning under one roof, and delivers MV contracting across Türkiye from 1 to 35 kV.
Miratek Elektrik Sistemleri Sanayi ve Ticaret Ltd. Şti. (miratekelektrik.com) is led by Founder, Board Member & CEO Musa Ekici and is headquartered in Osmaniye.
Key figures: 15+ years of experience, 1300+ completed projects and 12 active sites.
Site and manufacturing scale: 120 MVA of total transformer capacity, 85 km of MV/LV cable, 48 MV switchgear cells installed, 50 MW of installed SPP and 340+ panels manufactured.
Certificates: ISO 9001:2015, ISO 14001:2015, ISO 45001:2018 and TSE HYB.
Our Transformer Substations, Medium Voltage and Power Distribution Panels services run with a single point of contact from site survey to acceptance.
Frequently Asked Questions
What should you check first when choosing an MV electrical contractor in Türkiye?+
Start with completed and accepted projects at your voltage level and facility type. Then verify certificates against the issuing bodies' records, and ask about the contractor's own site team, test equipment and panel manufacturing capacity.
How do you verify a Turkish contractor's ISO and TSE HYB certificates?+
Check ISO certificates in the online register of the certification body that issued them, and the TSE HYB certificate through the Turkish Standards Institution's certificate inquiry service. The legal name, scope and validity date must match the entity you are contracting with.
What voltage range counts as medium voltage in Türkiye?+
Turkish regulations define medium voltage as above 1 kV up to 36 kV, and 34.5 kV is the most common distribution voltage. MV work requires utility approval and acceptance, specialist test equipment and trained crews, which makes it a distinct competence from low-voltage contracting.
Is it safe to pick the lowest bid for MV contracting work?+
Not until the scope is leveled. The lowest bid may hide missing scope, lower-specification materials or items that return as variation orders. Compare bids on the same bill of quantities, specification and inclusion and exclusion list.
Which regions of Türkiye does Miratek Elektrik serve?+
Miratek Elektrik delivers MV contracting across Türkiye, working from 1 to 35 kV on transformer substations, MV cabling, panels and solar site electrical works, with 1300+ completed projects and 12 active sites. Its headquarters are in Osmaniye.