Power grid

The French distribution network is often examined and compared with other European networks in terms of the balance between overhead and underground networks. This examination arises from environmental analyses, but also after meteorological phenomena such as the storms Lothar and Martin at the end of 1999, which argue against overhead systems. And questions quickly arise:

• why are there so many aerials?

• why don't we just do underground?

• why don't we speed up the burial of overhead networks?

The economic criterion is regularly put forward, but what does underground really cost compared to overhead?

In this dossier, we will attempt to answer some of these questions, mainly through a technical approach, in order to make the debate as objective and dispassionate as possible, while seeking to present a global vision of the air/ground problem.

Our experience is nonetheless French, having been forged in contact with distribution networks under concession to EDF (Électricité de France).

How does the network look today? How is it evolving, and under what political impetus; how do overhead and underground systems behave in the face of external aggression and bad weather?

The differences in design and operation between overhead and underground networks, how to switch from one to the other, and the economic elements of comparison are the subject of this dossier.

Obviously, the problem concerns rural and peri-urban areas, since most urban areas have long been underground for both medium-voltage (MV) and low-voltage (LV). But a few incursions into urban areas will allow us to mention the behavior of underground systems in this environment.