<Dd> Circuit that is isolated from power and not at a potential different from earth . Note the difference to permit to work . </Dd> <Dd> A branch supplying a side - socket or outlet, especially from a ring circuit . </Dd> <P> The standard wiring colours in the UK are (as of 2006) the same as elsewhere in Europe and follow international standard IEC 60446 . This colour scheme had already been introduced for appliance flexes in the UK in the early 1970s, however the original colour scheme recommended by the IEE for fixed wiring was permitted until 2006 . As a result, the international standard blue / brown scheme is as of 2006 found in most appliance flexes . In fixed wiring, the blue / brown scheme is only found in newer (post-2004) installations, and the old IEE black / red scheme is likely to be encountered in existing installations for many more decades . </P> <Table> <Tr> <Th_colspan="2"> </Th> <Th> Pre-1977 IEE </Th> <Th> Pre-2004 IEE </Th> <Th> Current IEC </Th> </Tr> <Tr> <Td_colspan="2"> Protective earth (PE) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="2"> Neutral (N) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Single phase </Td> <Td> Line (L) </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Three - phase </Td> <Td> L1 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> L2 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> L3 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> </Table>

When did the new wiring colours come in