Glass is not a good conductor of electricity and is classified as an insulator not a conductor. An electrical insulator is any material that does not allow electrons and electric charge to flow freely. These materials make it hard for electric current to flow.
Conversely, conductors are materials in which electrons and electric current can flow freely. Typical conductors include metals, such as copper, silver, gold, iron and brass. Typical insulators include nonmetals, such as glass, rubber, oil, pure water, plastic and quartz. Most solid materials are also good insulators, regardless of the materials of which they are made. This is because solid materials have a large resistance to electrical flow due to their crystalline tight structure.