shortcircuiting

Short-circuiting refers to two concepts: an electrical fault in circuits and a programming or logic technique in which evaluation stops early. In electronics, a short circuit is an unintended connection providing a path of very low resistance that bypasses designed components, causing current to flow along an undesired route.

Electrical short circuits lead to excessive current, which can cause overheating, insulation damage, arcing, fires, and damage to equipment. When resistance approaches very low values, the current can exceed component ratings and protective devices. Common causes include damaged insulation, faulty wiring, moisture, loose connections, or components that bridge conductors. Protection devices such as fuses, circuit breakers, and residual-current devices interrupt the supply to prevent damage. Good practice relies on proper insulation, correct conductor sizing, adequate clearance, and appropriate protection. Detection methods include thermal sensing, current monitoring, and fault-current testing.

In computing and logic, short-circuiting describes evaluating a boolean expression lazily: the evaluation stops as soon as the overall value is determined. For example, in many languages, A and B is evaluated as A first; if A is false, B is not evaluated, and the result is false. Similarly, A or B evaluates B only if A is false. This can improve efficiency and prevent unnecessary computations or side effects, but code that relies on a full evaluation or on side effects in later expressions can behave differently across languages. Some languages guarantee short-circuit behavior, while others define or permit variations in evaluation order and side effects.

Both uses rely on early termination to avoid unnecessary work, whether preventing hazardous current or skipping irrelevant computations.