Transformer explosion cuts power to 120,000 homes in Brittany amid heatwave
A transformer explosion at an RTE substation near Quimper left up to 120,000 households without electricity on Tuesday evening, as a heatwave pushed temperatures toward 40°C. Restoration is expected by midnight Wednesday.
Explosion and immediate blackout
A transformer at the RTE substation in Ergué-Gabéric, near Quimper (Finistère), exploded on Tuesday 23 June 2026 at around 21:00. Witnesses described a huge plume of smoke and debris thrown tens of metres into the air.
The blast, which the Finistère prefecture said was accidental and linked to the intense heat, triggered a massive power cut. At its peak, 119,000 to 120,000 households in southern Finistère lost electricity.There are pieces of aluminium flying everywhere. It rises to incredible heights. It's impressive.
Restoration timeline
RTE and Enedis crews worked through the night and the following day. By 16:00 on Wednesday, 38,500 homes were still without power; by 19:00 the number had fallen to about 15,000.
The operator expects the transformer to be recommissioned around 22:00, with progressive reconnection and full restoration around midnight. Orange reported 12,000 fixed lines and 3,000 mobile subscribers affected. Hospitals in Quimper and Pont-l'Abbé switched to backup generators.No, we don't have events like this regularly.
- Explosion at Ergué-Gabéric transformer; 120,000 homes lose power
- 38,500 homes still without electricity
- 15,000 homes remain cut off
- Full restoration expected around midnight
Heatwave strains grid across France
The Finistère incident was the most severe, but other regions also suffered heat-related outages. In Vaucluse, 5,000 customers were without power on Wednesday (9,000 at the Tuesday peak). Dijon saw 1,000 homes cut off for several hours, Cergy 2,500, and Toulouse and Balma 10,000 homes on Monday. Enedis explained that prolonged heat raises ground temperatures, especially under asphalt, preventing underground cables from cooling. Older paper-oil insulated cables, totalling 15,000 km of the 350,000 km medium-voltage network, are particularly vulnerable.
- Toulouse / Balma
- 10000 homes affected
- Vaucluse
- 5000 homes affected
- Cergy
- 2500 homes affected
- Dijon
- 1000 homes affected
Government and operator response
Despite the incidents, the government said the electricity system faces no supply tension.
EDF confirmed that heat-related constraints had forced it to stop one nuclear reactor and reduce output at two others, but the loss represented only 3.5% of installed nuclear capacity. RTE stated that no particular vigilance was required and that the French grid is robust. The operator plans €94 billion in investments by 2040 to adapt infrastructure to a 4°C warming scenario.We are not anticipating major tensions, nor tension on the supply-demand balance. We are still net exporters.
Health and safety measures
The power cut prompted swimming bans on several beaches in Combrit, Île-Tudy, Loctudy, Plobannalec-Lesconil, Treffiagat, Le Guilvinec, Penmarc'h, Plomeur and Douarnenez, due to the risk of degraded water quality from non-functioning sewage pumps. The prefecture warned of possible gastro-intestinal illnesses. Firefighters in Finistère recorded a 300% surge in activity, with 927 calls and 223 interventions by Wednesday evening.
