First of all, self-defense requires that illegal infringement exists and is happening. There is no illegal infringement in this case.
Second, legitimate defense requires the infringer himself, and the act of privately pulling the power grid is a threat to the life and health of any subject.
Third, legitimate defense requires that once it comes into contact with the power grid, it will cause serious damage to the lives and health of others, which seriously exceeds the limit of protecting watermelons as property. Generally speaking, we think that the right to life is greater than the right to health and property.
This behavior poses a threat to the lives of the unspecified majority. Even if warning signs are hung in the countryside, the lives of children with low education and illiteracy are threatened. If the actor takes a hopeful or laissez-faire attitude and leads to death, it is a typical crime of endangering public security by dangerous means and should be sentenced to fixed-term imprisonment of more than 10 years, life imprisonment or death.