The case concerns not only the electrical services or painting, but virtually every area.Therefore, many providers may boast all sorts of references.
To enable wires to be easily and safely identified, all common wiring safety codes mandate a colour scheme for the insulation on power conductors.In a typical electrical code, some colour-coding is mandatory, while some may be optional. Many local rules and exceptions exist per country, state or region.1 Older installations vary in colour codes, and colours may fade with insulation exposure to heat, light and ageing. As of March 2011, the European Committee for Electrotechnical Standardization (CENELEC) requires the use of green/yellow colour cables as protective conductors, blue as neutral conductors and brown as single-phase conductors.2 The United States National Electrical Code requires a green or green/yellow protective conductor, a white or grey neutral, and a black single phase.3 The United Kingdom requires the use of wire covered with green insulation, to be marked with a prominent yellow stripe, for safe earthing (grounding) connections.4 This growing international standard was adopted for its distinctive appearance, to reduce the likelihood of dangerous confusion of safety earthing (grounding) wires with other electrical functions, especially by persons affected by red-green colour blindness. In the UK, phases could be identified as being live by using coloured indicator lights: red, yellow and blue.
For this reason, three-phase control panels will often use indicator lights of the old colours.Źródło: https://en.wikipedia.org/wiki/Electrical_wiring#Colour_code
This is very important in facilities where daily scrolls many people, such as in high-blocks and so on.These modern systems make people feel much safer in their own home..