This multi-light electric fence tester not only indicates if your fence is electrified but if it is hot enough to keep animals secure. Capable of testing up to 5000 volts. Your fence should deliver as much shock as the charger. Measure the voltage at the chrger, then measure the voltage anywhere on the fence line. If there is considerable drop, look for causes: thick growths of weeds, fence wire brushing against wet wood or steel posts, insulators cracked or chipped.