You will notice the image here of a Ground Fault Receptacle.  The device has come a long way and is still in high demand.  What you see here is a device that has been overloaded on the “load side” terminals.  We are still allowed to install a 15ampere device on a 20ampere branch circuit, however, which does tend to cause the condition shown.  The other culprit is a lightning hit!  When installed correctly, taking in to account the load on the branch circuit, will give us many years of great service.