Electrical currents and circuits
An electrical current is the flow of electrons (charged particles) through a conductor. A circuit is required in order to allow the electrons to move. A simple circuit is any closed loop that allows a flow of electrons from a source of current to deliver energy and then return to the source. For example, in a light switch circuit, there is typically 120 volts of alternating current (VAC). A switch controls the electrical source, the light, and the return (ground).
Purpose of a ground
The purpose of an electrical ground is to allow any spikes in electricity to be directed away from the electric circuit and into the ground where it can be harmlessly absorbed. A ground serves as the return path for an electric circuit. A ground-fault occurs when there is a break in the low-resistance grounding path from an electrical appliance or instrument. The electrical current may then take an alternative path to the ground through the user, resulting in serious injuries or death. Body fluids that contain salts and ions allow electricity to flow, so humans are considered fairly good conductors of electricity.