IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Colour coding
Topic Summary: Use of 3 core cable for single phase circuit
Created On: 24 September 2012 09:26 AM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 24 September 2012 09:26 AM
User is offline View Users Profile Print this message



GMAC

Posts: 64
Joined: 12 September 2006

New 3 core armour cables are core coded brown, black, grey.
If using this for a single phase circuit is there anything in BS7671 or any of the guides to standardise which cores to use for L,N, &E, when using the 3 core cable in a single phase circuit. I appreciate the cores should be marked with brown, blue, and green/yellow at the ends regardless of which cores are used, but we have had experience of one company making one end off and another company making the other end off. If the coding was standardised there would be no need for the second company to check how the first company wired his end.
 24 September 2012 09:32 AM
User is offline View Users Profile Print this message



rutts

Posts: 127
Joined: 21 September 2012

As far as I'm aware there's nothing cast in stone. TBH it was no different with the old R, Y, B. they needed sleeving as well
 24 September 2012 09:46 AM
User is offline View Users Profile Print this message


Avatar for ebee.
ebee

Posts: 5681
Joined: 02 December 2004

No nothing set in stone.
Although logically the true colour (phase or line) might stay as is.
Now BROWN was Red.
Historically many thought that as BLUE was N in flexible s for quite a while that they might use it as N when we had R Y B colours so the Blue often was used as N (Often not sleeved in the real world I`m afraid).
Which left Y as the second L or as an Earth(Sleeved of course)
Therefore substituting Brown Black Grey for the old Red Yellow Blue
would become
Brown (L) , Black (second L or E as appropriate) and Grey as N.
Coincidently this leaves the association with Black as N in the past as some prefer.
But as I said nothing written in stone

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 24 September 2012 09:51 AM
User is offline View Users Profile Print this message


Avatar for sparkiemike.
sparkiemike

Posts: 1537
Joined: 24 January 2008

There were articles in the NICEIC connections magazine about this

It was in connections 151 (autum 2004) page 4


' DE-NEUTRALISING' BLACK
Under the new identification colours for fixed wiring introduced by Amendment 2 to BS 7671, black is now used to identify a phase conductor, not a neutral conductor, in new installation work.

Of course, for all single-phase applications, it would be preferable to use cables marked for such use, that is with brown, blue and green-and-yellow cores.

Breaking the black/neutral association
However, where three-core cables marked in the new three-phase colours are used for single-phase applications, it is proposed that, as a convention, the black core is used for the protective conductor, the brown for the phase conductor and the grey for the neutral. This convention is intended to break the association between black and neutral. It would mean that the black core would normally be overmarked green-and-yellow, and the grey core overmarked blue or N. The brown core would not need additional marking.

Street lighting
The Institute of Lighting Engineers (ILE) intends to introduce such a convention where SWA cables with brown, black and grey cores are used for street lighting applications, the black core being used as a circuit protective conductor in parallel with the armouring to maximise circuit lengths .

Fire alarm systems
Applying the same convention to a flat three-core fire alarm interlink cable, the grey would be overmarked as the neutral and the black interlink overmarked brown.


You should also read the article in connections 152 (pg 16(30)) as there is a correction with regard to smoke alarms


'DE-NEUTRALISING' BLACK - CORRECTION CONCERNING FIRE ALARM SYSTEMS
In the article entitled 'De-neutralising black', which was published in the previous (autumn) issue of Connections, reference was made to the identification of the brown, black and grey cores of a three-core cable when used as the phase, neutral and interlink (signal) conductors interconnecting smoke or heat alarms in a dwelling.

The article referred to the interlink (or signal) conductor being identified by the colour brown (i.e. by the application of a brown sleeve to the black core of the cable at its terminations). However, this advice did not take account of the recommendation given in clause 16.5(c) of BS 5839-6: 2004 - Code of practice for the design, installation and maintenance of fire detection and fire alarm systems in dwellings. The clause states, with regard to wiring in Grade D and E systems, that: 'Conductors used for interconnection of smoke/heat alarms should be readily distinguishable from those supplying power (e.g. by colour coding)'. (Grade D and E systems are systems with one or more mains-powered smoke alarms, the Grade D system smoke alarms having an integral standby.

The object of this recommendation of BS 5839-6: 2004 is to avoid the possibility of confusion between the interlink conductor, which generally operates at extra-low voltage, and the conductors providing the 230 V a.c. power supply. Therefore, the interlink conductor should be identified not by the colour brown (which is used for the phase conductor of the 230 V power supply) but by some other colour, appropriate to a phase conductor, which must be in accordance with the requirements of BS 7671. Table 51 of BS 7671: 2001 (as amended) specifies that where the phase conductor of a control circuit or extra-low voltage circuit is identified using the harmonised colour scheme, the colour used (excluding brown) shall be black, red, orange, yellow, violet, grey, white, pink or turquoise.

The simplest method of meeting this requirement is to use the black core of the cable as the interlink conductor, and to use the grey core as the neutral, marking it blue at the terminations. This convention is shown in the illustration and in the following table. The convention provides a way of meeting the relevant requirements of both BS 7671 and BS 5839-6 for the identification the phase, neutral and interlink (signal) conductors interconnecting smoke or heat alarms in a dwelling, where using a three-core cable in the new three-phase colours.
Convention for identification of cable cores interconnecting domestic smoke/heat alarms (three-core cable in new three-phase colours)

Function of conductor___Colour of core___Colour of marking at terminations
Phase of 230 V supply___Brown_________None
Neutral of 230 V supply____Grey__________Blue
Interlink______________Black_________None

Note: The circuit protective conductor should be sleeved green-and-yellow at its terminations in the normal way.

 24 September 2012 09:54 AM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11374
Joined: 13 August 2003

I think one of the "organisations" suggested using grey as N and black as PE to wean us off thinking off automatically thinking black is N (as it's now a line colour).

(The other option (other than using 2-core, which was the original intention on single-phase) is to use 3-core with brown/blue/green-yellow insulation - e.g. http://www.meteorelectrical.co...ed-armoured-cable.html )

- Andy.
 24 September 2012 04:13 PM
User is offline View Users Profile Print this message



broadgage

Posts: 1282
Joined: 07 August 2007

For single phase neutral and earth I believe that the recomendation is

BROWN=PHASE
GREY=NEUTRAL
BLACK=EARTH.

The grey and black conductors should of course be sleeved blue and green/yellow respectively.

AFAIK this is only a recomendation and not a requirement, I believe that black for neutral and grey for earth is permitted, if suitably sleeved, though not considered best practice.

Overseas electricians working in the UK seem to favour grey for earth, presumably because grey was used for earth in parts of Europe in the past.
 25 September 2012 07:27 AM
User is offline View Users Profile Print this message


Avatar for zeeper.
zeeper

Posts: 1409
Joined: 11 July 2008

Why did they change the colours again.
 25 September 2012 09:35 AM
User is offline View Users Profile Print this message


Avatar for tomgunn.
tomgunn

Posts: 3223
Joined: 25 May 2005

hahahahahahahahahahahahahahahahahahahahahahahahaha!!!!!

Hahahahaha!!!

.... .....

Ahhhhh... Tom

and... relaxxxxxxxxxxxxxxxxxxxxxxx

-------------------------
Tom .... ( The TERMINATOR ).

handyTRADESMAN ... haha

Castle Builders

Why did Nick Clegg cross the road? Because he said he wouldn't!

I can resist anything..... except temptation! ( Karl Gunn ).
 26 September 2012 08:51 PM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11374
Joined: 13 August 2003

Overseas electricians working in the UK seem to favour grey for earth, presumably because grey was used for earth in parts of Europe in the past.

Or they're aware of the old British standard of using black for N?

I gather grey for phase was a UK suggestion (together with white or pink) so that all three phases could have distinct colours - presumably because those colours weren't already used anywhere across CENELEC members.

http://electrical.theiet.org/w...sessment.cfm?type=pdf

- Andy.
 27 September 2012 11:36 PM
User is offline View Users Profile Print this message


Avatar for Dave69.
Dave69

Posts: 445
Joined: 16 July 2011

Brown is always phase
Grey Neutral
Black earth

i thought they changed the colours so colour blind sparks could tell the difference
 28 September 2012 07:26 AM
User is offline View Users Profile Print this message


Avatar for ebee.
ebee

Posts: 5681
Joined: 02 December 2004

Everybody I`ve spoken too (Colour Blind and Non Colour Blind) have told me it`s more difficult to distinguish the new colours!

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 28 September 2012 10:28 AM
User is offline View Users Profile Print this message


Avatar for spinlondon.
spinlondon

Posts: 4437
Joined: 10 December 2004

Does anyone actually know why the black has to br de-neutralised?
Is it just that the NICEIC think it would be a good idea, or is there some valid reason?
 28 September 2012 05:25 PM
User is offline View Users Profile Print this message


Avatar for weirdbeard.
weirdbeard

Posts: 1499
Joined: 26 September 2011

Originally posted by: spinlondon

Does anyone actually know why the black has to br de-neutralised?

Is it just that the NICEIC think it would be a good idea, or is there some valid reason?




Is it just a coincidence that in the 2004 nic article link below on de-neutralising black in single phase installations was given at the same time they announced part p? Has there ever been an article on 'de-phasing' blue in 3 phase circuits?



http://www.niceic.com/en/accou...s/Connections_151.pdf

I'm all for progress, and can cope with cables of any colour, but I think the harmonised colour change was in general a really stupid idea.
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.