An electrician is a tradesman who specializes in the electrical wiring of buildings and related equipment. Electricians may be employed in the construction of new buildings or just on the maintenance of an existing electrical infrastructure. In most countries, the job of an electrician is a regulated trade for safety reasons, requiring testing, registration, or licensing. Electricians are usually required to serve an apprenticeship lasting from 3 to 5 years under the general supervision of a Master Electrician and usually the direct supervision of a Journeyman Electrician.
Schooling in electrical theory and electrical building codes is usually required to complete the apprenticeship program. A Journeyman electrician is a well rounded craftsman trained in all phases of electrical construction installation in various building styles and maintenance of equipment after installation. A Master Electrician must first be a Journeyman and usually has a minimum of two years more experience and even then has to pass further testing. A Master Electrician is further trained in layout, estimation, and design of electrical installations.
In some jurisdictions a licensed electrician is required for permanent installation of any current carrying conductors, including low voltage alarm and data signal wiring, whereas in other places an electrician is only necessary for dealing with permanent connection at mains voltages, and yet others permit unlicensed homeowners to do all of their own electrical work (not "in the trade"), although it may still be subject to inspection for compliance with the relevant code or regulations, such as the US National Electrical Code or the UK IEE Wiring Regulations.