The maximum voltage allowed by law is 10,000 volts and the average setting is between 7,000 and 11,000 volts to allow for fluctuations. It’s not the voltage of the energizer that determines the shocking power of the fence. The shocking power is measured in Joules, 2 being an entry level energizer and designed for smaller properties and 8 being the maximum strength allowed in a residential area. These are typically complex energizers but are becoming more and more popular with residential houses.