"Ten fire engines are at the scene of a fire at a @NationalGrid site in #Ashford. Progress is being made & crews have worked to stop fire spread", the service tweeted.
The crews are expected to stay at the scene for some time, even though the blaze has been stopped.
The interconnection France-Angleterre power station is a vital part of the national grid of the UK. The electrical interconnector conducts electricity coming from France through a 70 km (43.5 miles) cable, partly lying under the sea.