Voltage is often confused for the amount of electricity used or delivered, but that is measured as amperage. Voltage is the speed with which electricity is delivered.
Joules are a measurement of work that are used in many applications, including electricity. In the case of electricity, it means either the amount of power necessary to produce 1 watt second, or the amount of power necessary to move a given charge through 1 volt.
Volts and Electric Fences
Voltage is directly proportional to the ability of a fence to deliver a shock. At least 3,000 volts is necessary for a fence to deliver a deterring jolt to animals.
Joules and Electric Fences
Joules on an electric fence indicate how much damage will be done when something comes into contact with an electric fence, which can be expressed as both electric shock and burning damage. Six to 12 joules is the norm for fences meant to deter animals.
Volts vs. Joules
High voltage is a good quality for any electric fence, although past 7,000 volts there is some potential for arcing. A high joules rating, especially above 20 joules, is for fences that are meant to injure those who come into contact with it.