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A '''short circuit''' (sometimes abbreviated to short or s/c) in an [[electrical]] [[circuit]] is one that allows a [http://en.wikipedia.org/wiki/Electric_current current] to [[travel]] along a path along where essentially no (or a very low) [http://en.wikipedia.org/wiki/Electrical_impedance electrical impedance] is encountered. The electrical [[opposite]] of a short circuit is an "[http://en.wikipedia.org/wiki/Open_circuit open circuit]", which is an [[infinite]] [[resistance]] between two nodes. It is common to misuse "short circuit" to describe any [[electrical]] malfunction, regardless of the [[actual]] [[problem]].

A '''short circuit''' (sometimes abbreviated to short or s/c) in an [[electrical]] [[circuit]] is one that allows a [https://en.wikipedia.org/wiki/Electric_current current] to [[travel]] along a path along where essentially no (or a very low) [https://en.wikipedia.org/wiki/Electrical_impedance electrical impedance] is encountered. The electrical [[opposite]] of a short circuit is an "[https://en.wikipedia.org/wiki/Open_circuit open circuit]", which is an [[infinite]] [[resistance]] between two nodes. It is common to misuse "short circuit" to describe any [[electrical]] malfunction, regardless of the [[actual]] [[problem]].

==Definition==

==Definition==

A short circuit is an [[abnormal]] low-resistance [[connection]] between two nodes of an [[electrical]] [[circuit]] that are meant to be at [[different]] voltages. This results in an excessive electric current (overcurrent) limited only by the [http://en.wikipedia.org/wiki/Th%C3%A9venin%27s_theorem Thévenin equivalent resistance] of the rest of the [[network]] and [[potentially]] [[causes]] circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused [[intentionally]], for example, for the [[purpose]] of voltage-sensing [http://en.wikipedia.org/wiki/Crowbar_(circuit) crowbar circuit protectors].

A short circuit is an [[abnormal]] low-resistance [[connection]] between two nodes of an [[electrical]] [[circuit]] that are meant to be at [[different]] voltages. This results in an excessive electric current (overcurrent) limited only by the [https://en.wikipedia.org/wiki/Th%C3%A9venin%27s_theorem Thévenin equivalent resistance] of the rest of the [[network]] and [[potentially]] [[causes]] circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused [[intentionally]], for example, for the [[purpose]] of voltage-sensing [https://en.wikipedia.org/wiki/Crowbar_(circuit) crowbar circuit protectors].

In [[circuit]] [[analysis]], the term short circuit is used by [[analogy]] to designate a zero-impedance [[connection]] between two nodes. This [[forces]] the two nodes to be at the same voltage. In an [[ideal]] short circuit, this means there is no resistance and no voltage drop across the short. In simple circuit analysis, wires are considered to be shorts. In real circuits, the result is a [[connection]] of nearly zero [http://en.wikipedia.org/wiki/Electrical_impedance impedance], and almost no resistance. In such a case, the current drawn is [[limited]] by the rest of the circuit.

In [[circuit]] [[analysis]], the term short circuit is used by [[analogy]] to designate a zero-impedance [[connection]] between two nodes. This [[forces]] the two nodes to be at the same voltage. In an [[ideal]] short circuit, this means there is no resistance and no voltage drop across the short. In simple circuit analysis, wires are considered to be shorts. In real circuits, the result is a [[connection]] of nearly zero [https://en.wikipedia.org/wiki/Electrical_impedance impedance], and almost no resistance. In such a case, the current drawn is [[limited]] by the rest of the circuit.

==Examples==

==Examples==

A common type of short circuit occurs when the positive and negative terminals of a [http://en.wikipedia.org/wiki/Battery_(electricity) battery] are [[connected]] together with a low-resistance [http://en.wikipedia.org/wiki/Electrical_conductor conductor], like a [http://en.wikipedia.org/wiki/Wire wire]. With low resistance in the connection, a high current exists, causing the cell to deliver a large amount of [[energy]] in a short time.

A common type of short circuit occurs when the positive and negative terminals of a [https://en.wikipedia.org/wiki/Battery_(electricity) battery] are [[connected]] together with a low-resistance [https://en.wikipedia.org/wiki/Electrical_conductor conductor], like a [https://en.wikipedia.org/wiki/Wire wire]. With low resistance in the connection, a high current exists, causing the cell to deliver a large amount of [[energy]] in a short time.

A large current through a battery can cause the rapid buildup of heat, potentially resulting in an explosion or the release of [http://en.wikipedia.org/wiki/Hydrogen hydrogen] gas and [http://en.wikipedia.org/wiki/Electrolyte electrolyte], which can burn tissue, cause blindness or even [[death]], and may be either an [http://en.wikipedia.org/wiki/Acid acid] or a [http://en.wikipedia.org/wiki/Base_(chemistry) base]. Overloaded wires can also overheat, sometimes causing damage to the wire's [[insulation]], or a fire. High current conditions may also occur with [http://en.wikipedia.org/wiki/Electric_motor electric motor] loads under stalled conditions, such as when the impeller of an electrically driven pump is jammed by debris; this is not a short, though it may have some similar effects.

A large current through a battery can cause the rapid buildup of heat, potentially resulting in an explosion or the release of [https://en.wikipedia.org/wiki/Hydrogen hydrogen] gas and [https://en.wikipedia.org/wiki/Electrolyte electrolyte], which can burn tissue, cause blindness or even [[death]], and may be either an [https://en.wikipedia.org/wiki/Acid acid] or a [https://en.wikipedia.org/wiki/Base_(chemistry) base]. Overloaded wires can also overheat, sometimes causing damage to the wire's [[insulation]], or a fire. High current conditions may also occur with [https://en.wikipedia.org/wiki/Electric_motor electric motor] loads under stalled conditions, such as when the impeller of an electrically driven pump is jammed by debris; this is not a short, though it may have some similar effects.

In [[electrical]] devices, unintentional short circuits are usually caused when a wire's [[insulation]] breaks down, or when another conducting [[material]] is introduced, allowing charge to [[flow]] along a [[different]] path than the one [[intended]].

In [[electrical]] devices, unintentional short circuits are usually caused when a wire's [[insulation]] breaks down, or when another conducting [[material]] is introduced, allowing charge to [[flow]] along a [[different]] path than the one [[intended]].

In [http://en.wikipedia.org/wiki/Mains_electricity mains] circuits, short circuits may not occur between two phases, between a phase and [http://en.wikipedia.org/wiki/Ground_and_neutral neutral] or between a phase and [http://en.wikipedia.org/wiki/Ground_and_neutral earth] (ground). Such short circuits are likely to result in a very high current and therefore quickly trigger an overcurrent protection device. However, it is possible for short circuits to arise between neutral and earth conductors, and between two conductors of the same phase. Such short circuits can be [[dangerous]], particularly as they may not [[immediately]] result in a large current and are therefore less likely to be detected. Possible [[effects]] include unexpected energisation of a [[circuit]] presumed to be isolated. To help reduce the [[negative]] [[effects]] of short circuits, power [[distribution]] transformers are deliberately designed to have a certain amount of [http://en.wikipedia.org/wiki/Leakage_inductance leakage reactance]. The leakage reactance (usually about 5 to 10% of the full load impedance) helps limit both the [[magnitude]] and rate of rise of the fault current.

In [https://en.wikipedia.org/wiki/Mains_electricity mains] circuits, short circuits may not occur between two phases, between a phase and [https://en.wikipedia.org/wiki/Ground_and_neutral neutral] or between a phase and [https://en.wikipedia.org/wiki/Ground_and_neutral earth] (ground). Such short circuits are likely to result in a very high current and therefore quickly trigger an overcurrent protection device. However, it is possible for short circuits to arise between neutral and earth conductors, and between two conductors of the same phase. Such short circuits can be [[dangerous]], particularly as they may not [[immediately]] result in a large current and are therefore less likely to be detected. Possible [[effects]] include unexpected energisation of a [[circuit]] presumed to be isolated. To help reduce the [[negative]] [[effects]] of short circuits, power [[distribution]] transformers are deliberately designed to have a certain amount of [https://en.wikipedia.org/wiki/Leakage_inductance leakage reactance]. The leakage reactance (usually about 5 to 10% of the full load impedance) helps limit both the [[magnitude]] and rate of rise of the fault current.

A short circuit may lead to formation of an [http://en.wikipedia.org/wiki/Electric_arc arc]. The arc, a channel of hot ionized [http://en.wikipedia.org/wiki/Plasma_(physics) plasma], is highly conductive and can persist even after significant amount of [[original]] [[material]] of the conductors was evaporated. Surface erosion is a typical sign of electric arc damage. Even short arcs can remove significant amount of [[materials]] from the electrodes.

A short circuit may lead to formation of an [https://en.wikipedia.org/wiki/Electric_arc arc]. The arc, a channel of hot ionized [https://en.wikipedia.org/wiki/Plasma_(physics) plasma], is highly conductive and can persist even after significant amount of [[original]] [[material]] of the conductors was evaporated. Surface erosion is a typical sign of electric arc damage. Even short arcs can remove significant amount of [[materials]] from the electrodes.

[[Category: Physics]]

[[Category: Physics]]