What Causes an Electrical Short Circuit?

Definition of a Short Circuit

By nature, electricity seeks to return to ground, and in a properly functioning circuit, this means that the current flows through the established wiring circuit back to the service panel, and onward back through the utility wires. However, if the connections within the wiring loosen or break, electrical current may "leak." In this instance, the electrical current instantly seeks to flow back to ground by a shorter pathway. That pathway may very well be through flammable materials or even through a human being, which is why a short circuit presents the danger of fire or lethal shock.

2 Types of Short Circuit

Short Circuit

The term short circuit is most commonly used by electricians to refer to the situation in which a hot wire carrying live current touches a neutral wire. When this happens, resistance lessens instantly and a large volume of current flows through an unexpected pathway. When this classic short circuit occurs, sparks sometimes fly, you may hear crackling, and sometimes smoke and flames ensue.

Ground Fault

A ground fault is a type of short circuit that occurs when the hot wire carrying current comes into contact with some grounded portion of the system, such as a bare copper ground wire, a grounded metal wall box, or a grounded portion of an appliance. As with the classic short circuit, a ground-fault causes resistance to instantly lessen, which allows a large amount of unimpeded current to flow through the unexpected pathway. Here, there is less chance of flame and fire, but a notable chance of shock.

3 Causes of Short Circuits

There are several causes for short circuits, including three that are most often to blame.

1. Faulty Circuit Wire Insulation

2. Loose Wire Connections

3. Faulty Appliance Wiring

3 Means of Protection Against Short Circuits

Because both classic short circuits and ground faults pose a danger of shock and fire, your wiring system has various means of safeguarding against those dangers.

1. Circuit Breakers or Fuses

2. Ground-Fault Circuit Interrupters (GFCIs)

3. Arc-Fault Circuit Interrupters (AFCIs)

Reference: https://www.thespruce.com/what-causes-short-circuits-4118973