For 3-phase supplies what are the standard wiring insulation colors?

Answer 1

In mains power generation terminology power is commonly generated at the power station in three separate "phases". The "Hots" ("Live" wires in European parlance) of each of the phases are timed to "lag" each other in wave/cycle terms as follows: the Hot of the first phase is generated at 0o (Zero degrees, which is equivalent to 360o), the Hot of the 2nd phase is timed to lag the Hot of the the first phase by 120o and the Hot of the third phase is timed to lag the Hot of the first phase by 240o. In Europe, where power is generated at 50Hz, the "Hots" (labelled as lines L1, L2 and L3) making up each of the three phases commonly have the colors Brown for L1, Black for L2 and Grey for L3; the Neutral wire is Blue. (These are equivalent to the UK's old wiring regulations for 3-phase supply cable of Red, Yellow and Blue where the Neutral wire was Black.) Perhaps someone else could say what the colors for the Hots are in the US or other countries which use 3-phase power generated at 60Hz? A new question will be asked about this. The number of phases delivered from the street to a building depend on its power usage requirements: an industrial building or site which uses 3-phase power for powerful motors, ovens, etc. must have its electricity delivered as 3-phase power; commercial offices or domestic homes typically only use single-phase lights and appliances, so such homes and offices usually only require 1-phase (single-phase) power to be delivered from the street. Note: For mains power any 1-phase supply is usually obtained by using just one phase of a 3-phase supply that comes in overhead or underground cables from the generating station. The power company typically supplies a given neighborhood with 3-phase power and distributes it as separate 1-phase supplies, one phase per street or group of streets, so that each house in each street gets its 1-phase power.

If the owner requires it, it is usually possible to pay the power company to provide a 3-phase supply into a house or any other type of property, such as an engineering workshop, vehicle repair garage, etc., that may need to have a 3-phase supply to power heavy equipment such as big motors installed in machinery.