According to French trade outlet DCmag, citing press reports, Anthropic and OpenAI are now exploring 20 to 30 MW capacity alongside their multi-hundred-megawatt campuses. In France, that size is not just a real estate choice: it can change which grid operator you deal with, and therefore your timeline.
THE RULE FEW PEOPLE LOOK AT
In France, a consumer site can in principle connect to the medium-voltage distribution grid, run mainly by Enedis, up to a power limit equal to the lower of two figures: 40 MW, or 100 MW divided by the distance in kilometres to the nearest transformation substation. Above that, the connection falls under RTE's transmission grid.
In other words, a 20 to 30 MW data center a few kilometres from a primary substation can stay outside the transmission procedure. The closer it is, the more power it can take.
| Distance to the primary substation | Maximum power on the distribution grid | A 20 MW site | A 30 MW site |
|---|---|---|---|
| 2.5 km or less | 40 MW | Eligible | Eligible |
| 3 km | about 33 MW | Eligible | Eligible |
| 4 km | 25 MW | Eligible | Above: transmission grid |
| 5 km | 20 MW | At the limit | Above: transmission grid |
| 8 km | 12.5 MW | Above: transmission grid | Above: transmission grid |
GridReadiness calculation based on the power limit set in Enedis connection terms: the lower of 40 MW and 100/d MW, where d is the distance in km to the nearest HV/MV transformation point. Indicative values; actual feasibility depends on primary substation capacity.
WHAT IT CHANGES FOR A PROJECT
A different counterparty and procedure. The project follows Enedis's connection procedure rather than RTE's, outside the transmission queue that large projects are crowding.
A potentially shorter timeline, especially on a site close to a primary substation with spare capacity. That is the logic of urban, right-sized data centers such as those PHOCEA DC is developing in Marseille.
Far more candidate sites. There are many more locations near a primary substation than sites able to host several hundred megawatts, including in regional cities and urban brownfields.
THE PITFALLS
The substation may be full. Proximity does not guarantee capacity. If the substation transformer needs reinforcing, the timeline depends again on heavy works and transformer lead times. Recent framework agreements between Enedis and manufacturers, such as the one signed with Hitachi Energy, secure part of that equipment.
Reserved capacity is no longer permanent. Since August 2025, a readjustment mechanism can bring a medium- or high-voltage consumer's connection capacity down to its maximum observed demand over five years plus 25%. For a data center filling up in phases, that needs to be planned.
Permits still apply. A 20 to 30 MW site remains subject to planning, environmental and, depending on its generators, classified-installation rules. In a city, proximity to residents makes community acceptance even more sensitive. See our crisis management method.
Smaller does not mean simpler. AI racks need liquid cooling and dense power distribution. An existing building is not necessarily adaptable without replacing much of its equipment.
QUESTIONS TO ASK ON A 20–30 MW SITE
Does the substation have capacity, or is reinforcement needed?
What is the ramp-up plan, given the readjustment of reserved capacity?
Can the building take liquid cooling and high power density?
Which permits are needed, and what is the local context?
Our guide to reviewing an RTE or Enedis connection offer covers the process.
FREQUENTLY ASKED QUESTIONS
Can a 30 MW data center connect to the Enedis distribution grid in France?
Yes, if it stays under the regulatory limit for the distribution grid: the lower of 40 MW and 100 MW divided by the distance in km to the nearest transformation substation. A 30 MW site therefore needs to be within about 3.3 km of the substation, subject to available capacity.
What is the maximum connection capacity on the French medium-voltage grid?
Under Enedis connection terms, the limit is the lower of 40 MW and 100/d MW, where d is the distance in kilometres to the nearest HV/MV transformation point. Above that, the connection falls under the transmission grid.
Why are AI companies interested in 20 to 30 MW data centers?
Because they can be energised faster than giant campuses, especially for inference, and in France they can often connect to the distribution grid rather than the transmission grid.