In the United States, electricians are divided into two primary categories: linemen, who work on electric utility company distribution systems at higher voltages, and wiremen, who work with the lower voltages utilized inside buildings.
Wiremen are generally trained in one of five primary specialties: commercial, residential, light industrial, industrial, and low-voltage wiring, more commonly known as Voice-Data-Video, or VDV.
Other sub-specialties such as control wiring and fire-alarm may be performed by specialists trained in the devices being installed, or by inside wiremen. Electricians are trained to one of three levels: Apprentice, Journeyman, and Master Electrician.
Construction electricians primarily focus on larger projects, such as installing all new electrical system for an entire building, or upgrading an entire floor of an office building as part of a remodeling process.
Other specialty areas are marine electricians, research electricians and hospital electricians."Electrician" is also used as the name of a role in stagecraft, where electricians are tasked primarily with hanging, focusing, and operating stage lighting. In this context, the Master Electrician is the show's chief electrician.
Contractors are responsible for generating bids for new jobs, hiring tradespeople for the job, providing material to electricians in a timely manner, and communicating with architects, electrical and building engineers, and the customer to plan and complete the finished product. Źródło: https://en.wikipedia.org/wiki/Electrician#Terminology
Building wiring is the electrical wiring and associated devices such as switches, meters and light fittings used in buildings or other structures. Electrical wiring uses insulated conductors. Wires and cables are rated by the circuit voltage, temperature and environmental conditions (moisture, sunlight, oil, chemicals) in which they can be used, and their maximum current.
Wiring safety codes vary by country, and the International Electrotechnical Commission (IEC) is attempting to standardise wiring amongst member countries.
Colour codes are used to distinguish line, neutral and earth (ground) wires.Źródło: https://en.wikipedia.org/wiki/Electrical_wiring
In such cases it may refer to an electrical emergency, which most often work electricians with high seniority and professional experience in the repair of different faults.