Why Are Joules Important?
Joules are important because they indicate the power of an electric fence charger’s shock. Specifically, they measure how much heat would be generated if an electric fence charger administered its maximum potential shock. That doesn’t mean that a horse contacting a conductor powered by a 6-joule charger would actually receive a 6-joule shock, it just means that it is theoretically possible if the horse received the charger’s full output. This says something about effectiveness, because some of the electric energy that a charger puts on the electric fence line is dissipated by resistance on the line and also by electricity leaving the line through weeds and brush–all of which diminishes the remaining joules and also diminishes the voltage available to shock target animals. At some point the voltage dips below the 4 kilovolts needed to reliably shock a horse through its hair and skin; and at some further point it drops below the 3 kilovolts needed to marginally shock a horse. All other t
