Electric Fence Light (Z-Bulb Plus) let’s you know that your electric fence is working good. As long as the light is flashing with every pulse of the fence charger it means all is OK. If the light is not flashing, it means that there is a draw on the fence. For adjustments adjust the Spark Gap as wide as you can with it still being able to spark. This sensitizes the Spark Gap with your whole fence and if anything touches the fence the light will disengage and sends the full shock to what ever is touching the fence. Remember the Spark Gap only draws current until something else touches the fence and it will not spark until whatever touched the fence is gone.