UK
electric power cable colours are changing...
In March 2004 an amendment to British Standard BS 7671 ('Requirements
for Electrical Installations') brings UK colour coding of
electric cables into harmony with most other EU member countries.
'2
core and earth' (Twin and Earth) cable
Pre-March
2004 the UK standard for '2 core and earth' cable used
in single phase (i.e. normal household) installation was:
Live = Red
Neutral = Black
Earth = Green and Yellow
sleeving
(Note: the earth wire is normally a bare copper conductor
within the T & E cable. The term
Green and Yellow
applies to the coloured sleeving which must be fitted
over the bare earth wire).
Post-March 2004 the UK standard was changed to:
Live = Brown
Neutral = Blue
Earth = Green and Yellow
sleeving (no change)
(Note: This new colour coding is the same as used for
appliance flexes in the UK for many years.)
'3
core and earth' cable (eg, used for two way lighting
circuits)
Pre-March 2004 the UK standard for '3 core and earth'
cable used in two way lighting was blue,
yellow and red
with a bare copper earth.
Post-March
2004 the UK standard was changed to Grey,
Black and Brown
with a bare copper earth.
Why
the change ?
The change is the result of international standardisation
(or harmonisation) with most of Europe already using this
colour coding - the new colours are sometimes referred
to as 'harmonised'.
How
will the change come into effect ?
The
new colours came into effect on 1st April 2004. However
there is a two year overlap between the old and new colour
coding.
Until
31st March 2006, either the old colours or new colours
may be used (but not mixed).
From
1st April 2006, the old colours will not be permissible
in new installations or when making changes.
Where
new colour cable is used to extend an existing 'old colour'
installation before 1st April 2006, a warning notice (see
below for an examplele) must be fixed at the main distribution
or consumer unit of the installation.

Three
Phase wiring
The Red, Blue and Yellow phase wires (and Black for Neutral)
will also change colours.
Please consult the IEE
website for complete details.
More
information
http://www.iee.org/Publish/WireRegs/cablecolfaq.cfm
A
promotional flyer/expanatory leaflet is available in PDF
format (278KB) on this IEE page: http://www.iee.org/publish/wireregs/cablecol.cfm
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