This is because the material inside of the wires is a conductor. Conductors are materials that electrons can travel through easily. Conductors are usually made out of metals. Conductors are used in the electrical wiring itself! Humans are also conductors of electricity (that is very dangerous) That is why humans should wear insulators to protect themselves from electricity. Examples of conductors are gold, copper, silver, and iron! The outside of an electrical wire keeps it so that the wire is safe to touch. The material the is coating the wire is called an insulator. Insulators and materials that do not let electrons flow through them. Insulators are usually made out of polymers, or linked particles (only sometimes). Examples of insulators are rubber, cotton, plastic, rubber, and wood. This is how electrical wires work!