Linked from
The 14 pages that link to Electrical breakdown, each with the reason it gives.
Electrical insulatorRelated: Breakdown marks the limit of an insulator’s ability to block current.
Electrical insulationCompared with: It is the failure insulation is designed to prevent.
Electrical arcRelated: Breakdown initiates the conductive path across a gap where an arc can form.
Neon lightingRelated: A sufficiently strong electric field ionizes the gas and starts the discharge.