Three-phase connection for a commercial space or warehouse
Connecting a commercial space or an industrial warehouse to the three-phase power grid (400V) is a technical project with high installed power, where every kilowatt requested influences the connection solution. As a guideline, a three-phase overhead warehouse electrical connection (bransament) starts from 2,900 lei, the underground version from 3,500 lei, and the connection dossier and design from 900 lei. The final price, however, is set only through the ATR (Technical Connection Approval), issued by the distribution operator Retele Electrice Romania S.A. (formerly E-Distributie Muntenia). SUN WATT SRL, ANRE-certified for both execution and design, manages the entire process of commercial space connection in Bucharest, Ilfov and Giurgiu.
Why the requested power matters for a warehouse or commercial space
For residential buildings, the choice is simple: single-phase (~11 kW) or three-phase. For commercial spaces and warehouses, the maximum simultaneously absorbed power can range from a few tens to several hundred kW, depending on the installed equipment: production lines, compressors, motors, ventilation and air-conditioning systems, EV chargers, cold storage facilities, industrial lighting.
This power determines the connection solution:
- Small-to-medium power levels (up to ~100-120 kW) can usually be connected directly from the operator’s low-voltage grid (0.4 kV), via a classic three-phase connection.
- High power levels (above ~100-250 kVA) most often require a medium-voltage connection and the construction of a dedicated (consumer-owned) transformer station or a transformer station shared with the operator.
The exact threshold at which the transition from low voltage to medium voltage occurs is not fixed; it results from the solution study and from the availability of the grid in the respective area. This is why correctly sizing the power requested through the connection application is the most important step of the entire project.
Steps for connecting a commercial space to three-phase power
The B2B process follows the same regulated logic as any grid connection, but with additional technical documentation requirements:
1. Determining the power and the connection dossier
The power balance of the consumers is calculated and the connection dossier is drawn up together with the related design (from 900 lei). The documentation includes the urban planning certificate, the company’s documents, the site plan and the technical data of the installation.
2. The connection application and the ATR
The dossier is submitted to Retele Electrice Romania S.A. The operator issues the Technical Connection Approval (ATR), which specifies the technical solution, the connection point, the approved power and the final connection tariff. We recommend ATR assistance (from 350 lei), so that the approved power and solution are optimal from both a technical and a financial standpoint.
3. Designing the utilisation installation
After the ATR, the utilisation installation is designed: distribution boards, distribution, protections and, where applicable, the transformer station. This is also where the earthing system (from 900 lei) and the PRAM report (from 250 lei) come in, both mandatory for acceptance.
4. Executing the connection and the installation
SUN WATT executes the electrical connection (overhead or underground), the indoor electrical installation and, where applicable, the transformer station, in compliance with ANRE standards and the solution set out in the ATR.
5. Energisation and the supply contract
After inspections, the signing of the acceptance report and the issuing of the certificate of conformity, the meter is installed and the energy supply contract is signed.
Indicative price table for B2B connections
The prices below are indicative; the final value of the connection tariff results from the ATR and depends on power, distance and the approved technical solution.
| Service / works | Applicability | Indicative price (from) |
|---|---|---|
| Three-phase overhead connection (400V) | Commercial spaces, small workshops | 2,900 lei |
| Three-phase underground connection | Warehouses, logistics parks, urban areas | 3,500 lei |
| Temporary site connection | Warehouse construction phase | 2,200 lei |
| Connection dossier + design | Mandatory, any power level | 900 lei |
| ATR assistance | Solution and power optimisation | 350 lei |
| Power upgrade (spor de putere) | Extending existing consumption | 350 lei |
| Earthing system | Mandatory at acceptance | 900 lei |
| PRAM testing | Earthing system report | 250 lei |
| Transformer station | High power levels (MV) | price on request, via ATR |
For a personalised estimate based on the requested power, use the electrical connection cost calculator or consult the full prices page.
Direct connection or a dedicated transformer station?
The decision depends on the approved power and the configuration of the grid in the area.
Low-voltage connection (classic three-phase connection)
- Suitable for commercial spaces, shops, workshops and small warehouses with power up to ~100-120 kW.
- Lower investment cost, faster energisation.
- Minimal maintenance on the beneficiary’s part.
Medium-voltage connection with a transformer station
- Required for production warehouses, large cold storage facilities, factories and high-power consumers.
- Involves a transformer station (consumer-owned or shared), with a transformer sized in kVA.
- Higher initial investment, but more advantageous energy tariffs and a power reserve for expansions.
- Requires additional permits, a medium-voltage design and specific acceptance.
In many cases, a modern warehouse project provides for a medium-voltage connection with a dedicated transformer station from the outset, in order to avoid redesign should production later be expanded. The solution study in the ATR stage clarifies the optimal option.
DIU and aspects specific to industrial warehouses
For complex projects, SUN WATT also provides a Site Supervisor / DIU (Utilisation Installation Dossier / proof of internal installation) (from 1,200 lei), useful when the connection is part of a larger investment involving several contractors. For warehouses, attention focuses on:
- Protection selectivity and the correct sizing of power cables;
- Power factor correction (capacitor banks), to avoid penalties;
- The earthing system and the earthing of metal structures and equipment;
- Backup supply (generator set / UPS) where the process does not tolerate interruptions.
All these elements are correlated with the solution set out in the ATR and with the regulations in force.
Why choose SUN WATT for connecting your commercial space or warehouse
- ANRE-certified for the execution and design of electrical connections;
- Experience with B2B projects in Bucharest, Ilfov and Giurgiu;
- We fully manage the relationship with Retele Electrice Romania S.A.: dossier, ATR, execution, acceptance;
- Solutions for any power level, from a three-phase connection to a transformer station;
- DIU available nationwide.
For an assessment of the required power and a firm quote, contact us on 0733 097 440 or via the contact page. We help you choose the right commercial space connection solution as early as the design phase, so you avoid later costs and delays.