Interloper wrote:

"Tim Watts" wrote

Give me a few hours - I think I can back that up...

OK, over to you, then ;-)

BS7671:2008 17th Edition pre Amendment 1:

514.4.2 (Excerpt):

"The bi-colour combination green-and-yellow shall be used exclusively for
identification of a protective conductor and this combination shall not
be used for any other purpose."

This rule is referring specifically and only to the colour identification
of
a conductor (at the termination point). If the conductor colour is the
bi-colour combination of green-and-yellow , then that conductor must be a
CPC. The bi-colour combination of green-and-yellow shall not be used for
any other purpose. However, this rule has no bearing on the reassignment
of
a green/yellow conductor by oversleeving with a different colour at the
termination points.

Single-core cables that are coloured green-and-yellow throughout their
length shall only be used as a protective conductor and shall not be
over- marked at their terminations, except as permitted by Regulation
514.4.3..."

This rule specifically precludes the reassignment of a single-core
green/yellow conductor for any other purpose. I suggest this rule exists
to ensure reassignment of a green/yellow conductor will only occur in a
multicore cable. This rule would be superfluous if the reassignment of a
green/yellow conductor was not permitted under any circumstances. The
rule could have been made much clearer.

Yes, it makes a big point of single-cores but the overall meaning is
pretty
clear - it would be a brave man that would argue against that. IMHO the
first sentence covers all eventualities and the second is just
reinforcement.

The first rule (sentence) is very clear about the use of the bi-colour
combination of green-and-yellow only. It refers just to the colour
identification, and not to conductor reassignment.

It's a compelling argument - I'm inclined to change my POV about the
interpretation. I still maintain that it's a bad idea though.

Yes - but even qualified electricians don't like being caught out with
extreme weirdness ;- This is why there are colour standards - which are
otherwise arguably irrelevant to safety as the electrons don't really
care.

IMO, the colour standards are now a mess that frequently has to be
clarified
by the use of additional alpha-numerical identifiers.. The latest colours
were chosen as the EU standard in such a way that no country could be seen
to be at an advantage as a consequence of the colour standard they were
already using. At least the UK was instrumental in persuading the other
European countries to adopt three different phase colours (brown, black
and
grey, rather than brown, black, black). It's taken since 1969 to agree
and implement these colour changes!


Yep.

--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"A fanatic is one who can't change his mind and won't change the subject."