The term electrical breakdown or electric breakdown has several similar but distinctly different meanings. For example, the term can apply to the failure of an electric circuit

Electrical network

An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources and switches. An electrical circuit is a special type of network, one that has a closed loop giving a return path for the current...

.
Alternatively, it may refer to a rapid reduction in the resistance of an electrical insulator

Insulator

Insulator may refer to:* Insulator , a substance that resists the flow of electric current* Insulator , an element in the genetic code* Thermal insulation, a material used to resist the flow of heat...

 that can lead to a spark

Electric spark

An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air...

 jumping around or through the insulator. This may be a momentary event (as in an electrostatic discharge

Electrostatic discharge

Electrostatic discharge is a serious issue in solid state electronics, such as integrated circuits. Integrated circuits are made from semiconductor materials such as silicon and insulating materials such as silicon dioxide...

), or may lead to a continuous arc

Electric arc

An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. A synonym is arc discharge. An arc discharge is characterized by a lower voltage than a glow discharge, and relies on...

 discharge if protective devices fail to interrupt the current in a high power circuit.
The most common meaning is related to automobile

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

s and is the failure of an electric circuit or associated device resulting in a loss of vehicle function (a breakdown).