Power upgrade and switching from single-phase to three-phase: when and how much it costs
If your electrical installation “trips” when you switch on several appliances at once, or if you want to install a heat pump, an EV charger or machinery, you need either a power upgrade (spor de putere) or a switch from single-phase to three-phase. This article explains the difference between the two, when they are needed, what steps they involve and how much they cost, with indicative prices from SUN WATT SRL, an ANRE-certified company for the design and execution of electrical connections (bransamente) in Bucuresti, Ilfov and Giurgiu.
What a power upgrade means and what switching to three-phase means
The two concepts are often confused, but they are not identical.
- Power upgrade (spor de putere) = increasing the approved power (kW) for your place of consumption, regardless of whether you stay on single-phase or move to three-phase. It is carried out when your current contracted power no longer covers your consumption.
- Switching from single-phase to three-phase = changing the type of supply, from a single phase (230 V) to three phases (400 V). It usually also brings a power upgrade, because three-phase allows higher power to be distributed evenly.
In short: you can request a power upgrade on single-phase (within certain limits), but above a certain threshold, the grid operator Retele Electrice Romania S.A. (formerly E-Distributie / Enel) will require you to switch to three-phase.
When you need a power upgrade
- The fuse board trips frequently when the water heater, hob, washing machine and air conditioning run simultaneously.
- You have installed, or want to install, a heat pump, photovoltaic panels with a larger inverter, or an extensive climate control system.
- The power approved in your contract (for example 5-6 kW single-phase) no longer covers your actual consumption.
When you need to switch to three-phase
- You want to install an EV charger (wallbox) of 11 kW or 22 kW, which requires three phases.
- You have machinery, motors or industrial equipment that only operate on 400 V.
- You need a higher installed power (above the usual single-phase threshold, generally around 8-11 kW, depending on the operator’s conditions).
- You are building a large house with many appliances, a workshop or a commercial space.
The steps for a power upgrade or switch to three-phase
The procedure is similar to a new connection and also goes through the distribution operator. Here are the main stages:
- Assessment and power requirements. You establish, ideally with the help of a specialist, the power you need (kW) and whether you stay on single-phase or move to three-phase.
- Preparing the grid connection (racordare) dossier. Application to Retele Electrice Romania, ownership documents, site plan, place-of-consumption data sheet. See the connection dossier service.
- Issuing the ATR (Technical Connection Approval). The operator reviews the application and issues the ATR, the document that establishes the technical solution and the final connection tariff.
- The connection contract signed with the operator, based on the ATR.
- Design and DIU. The technical documentation is prepared and, where applicable, the Utilisation Installation Dossier (DIU).
- Execution of works. Replacing the connection, fitting a new fuse board, a three-phase meter, and rewiring where needed.
- Energisation (PIF) and updating the supply contract with the new approved power.
For the dedicated steps, see the service pages for power upgrade increase and switching from single-phase to three-phase.
How much it costs: indicative prices
The total cost has two components: the connection tariff set by the operator through the ATR (variable, depending on power and distance) and the works/documentation carried out by the ANRE-certified company. Below are indicative SUN WATT SRL prices:
| Service | Indicative price (from) | Notes |
|---|---|---|
| Single-phase connection | 1,800 lei | Basic solution, lower power |
| Three-phase connection | 2,900 lei | Recommended for a large upgrade / 11-22 kW wallbox |
| Underground connection | 3,500 lei | When the grid or aesthetics require the buried option |
| Temporary site supply | 2,200 lei | Useful during construction, then made permanent |
| DIU (Utilisation Installation Dossier) | 1,200 lei | Documentation only, no labour |
| Connection dossier | 900 lei | Preparation and submission to the operator |
Important: these figures are indicative. The final price is set through the ATR, depending on the technical solution approved by Retele Electrice Romania S.A. For a quick estimate, use the connection cost calculator or check the prices page.
Practical cost examples
- Switching single-phase -> three-phase for an 11 kW wallbox: three-phase connection from 2,900 lei + connection dossier from 900 lei + DIU from 1,200 lei, plus the connection tariff from the ATR.
- Power upgrade on single-phase (without changing the phase): in many cases this only involves updating the dossier, a connection dossier from 900 lei and, possibly, minor replacements.
How long it takes
The timeframe depends on the complexity of the solution and on the operator. As a guide:
- Preparing and submitting the connection dossier: a few days.
- Issuing the ATR: generally between 30 and 90 days, in line with the regulated timeframes, depending on the power and type of connection.
- Execution and energisation after signing the contract: usually 1-3 weeks for the actual work.
With a complete and correctly prepared dossier from the start, you avoid returns and shorten the timeframes.
Single-phase vs. three-phase: which to choose
| Criterion | Single-phase (230 V) | Three-phase (400 V) |
|---|---|---|
| Usual power | up to ~8-11 kW | from ~11 kW upwards |
| 11/22 kW wallbox | no | yes |
| Large heat pump | limited | recommended |
| Consumption balancing | poorer | better |
| Initial cost | lower (from 1,800 lei) | higher (from 2,900 lei) |
If you have future plans (electric car, heat pump, workshop), switching directly to three-phase is usually more economical than two separate interventions.
Why SUN WATT SRL
- ANRE-certified for the design and execution of electrical connections.
- Coverage across Bucuresti, Ilfov and Giurgiu, plus DIU nationwide.
- We handle the entire process: connection dossier, dealings with Retele Electrice Romania S.A., design, DIU and execution.
Want to know exactly how much power you need and what it will cost you? Call 0733 097 440 or write to us through the contact page for an assessment and a personalised quote.