To explain the purpose of an invisible dog fence, it is important to know how it works. Basically, you control the boundary that your dog can go by having a wire installed just underground. The dog will wear a collar that has a direct connection to the fence.
That connection does a few things. With most systems, if a dog gets closer to a boundary, he will start to hear a beeping noise. If he keeps going further, he will get a small electrical impulse, telling him to back off from that area. This does not hurt the dog; it just makes him aware of his surroundings.
If you’re dog is still relying on the invisible fence, beware of the power going out in your house. Systems are set up to run power from your house so if you have a back-up generator, make sure the invisible fence is on the circuit too.
Once your dog gets the idea of what the boundaries are, you should be able to turn down the impulse on the collar. If you notice that he doesn’t go near them at all anymore, you might even consider putting a “dummy” collar on him that doesn’t provide a shock.