Bob Schmidt shows you a great tool to have when starting a home renovation project. An electric tester can help prevent accidental electric shock when working with electric. It is how to find out if a wire is hot and help determine the circuit in the electric panel to shut off. abandoned wires are very difficult to determine and junction boxes sometimes have more than one circuit going through them so it is very important during disconnect to know the wires that are live, How to know if electric wire is hot active? how to shut off correct circuit breaker. Electric wire just hanging in wall not connected to anything. plug wire connected to switch ? how to tell if a wire is hot or not? DIY