UK Low Voltage Cable Colour Harmonisation

Source: Wikipedia article for Electrical Wiring (UK)

The standard colours for fixed wiring in the UK were harmonized in 2004 with the regulations in other European countries and the international IEC 60446 standard. For a transitional period (April 2004 - March 2006) either set of colours were allowed (but not both), provided that any changes in the colour scheme are clearly labelled. From April 2006, the new colours must used for any new wiring.