An electric fence works when the fence energizer converts mains power into a high voltage pulse to an insulated fence line about once every second. Fences often function as psychological barriers rather than physical barrier, teaching animals to respect the fences, while the pain is short-lived.
Every electric fence has three basic components. A wire fence carries an electric charge and an energizer, also known as a charger, which pushes power through the fence, delivering the power in a series of pulses--normally about one per second. The time between pulses allows the animal to break free of the fence because a continuous current may make the animal unable to let go. A ground system, which is usually a series of metal rods sunk into the ground and connected to the energizer through a ground wire, waits dormant until any animal touches the fence. The system attracts the charge through the animal and returns the current to the energizer through the ground wire.
The strength of the shock depends on two basic variables: voltage and amperage. The higher the voltage, the longer the distance the current can travel through the wire before resistance slows it down, causing a stronger startle. The higher the amperage, the greater the sensation the current causes. The level of unpleasantness depends more on the amperage than on the voltage.