When a short circuit occurs, electrical current experiences little to no resistance because its path has been diverted from its normal direction of flow. This in turn produces excess heat and can damage or destroy an electrical appliance. It can also create a fire hazard and an electrical shock hazard if left unattended.

A short circuit happens when part of a wire carrying electricity touches another part of the circuit or other conductive material, thus giving electricity a pathway that offers less resistance than the circuit is designed to handle. For example, if a wire becomes exposed and touches the metal frame of a device, current can flow along the outside causing the potential for injury and death if someone touches the charged device. A short circuit, as suggested by the name, provides electricity with a shorter path to ground or to equalize electrical potential across two terminals. Less distance means less resistance, thus producing more heat which can cause fire or burns. To protect against short circuits, all materials and conductors in electrical equipment should be maintained and checked regularly; wires should never be bent tightly or crimped because the cord can easily fray. Also, no circuit should be overloaded.