flashover

English

Etymology

Deverbal from flash over.

Noun

flashover (countable and uncountable, plural flashovers)

  1. The near simultaneous ignition of all combustible material in an enclosed area.
    • 2026 January 1, Chris Michael, Rory Carroll, “‘It happened in seconds’: sudden inferno brings horror to Swiss ski resort”, in The Guardian[1], →ISSN:
      The blaze turned into what Swiss officials called an embrasement généralisé, a term for a fire that releases combustible gases that can ignite violently, triggering what English-speaking firefighters call a flashover or backdraft.
  2. An unintended electric discharge or arc over or around an insulator.
    Synonym: sparkover
    • 1960 April, “Talking of Trains: Safety with 25kV a.c.”, in Trains Illustrated, page 203:
      The overhead line was energised at 25,000 volts and the height of the contact wire was reduced to 11 in. above the chimney, then to 5 and finally to 2 in.; at this last, short distance the flashover occurred, but all the men were perfectly safe because the current went direct to earth through the locomotive.

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