"Tim Watts" wrote:

Interloper wrote:

Adam wrote:

Reg 514.4.2

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

I would suggest that this regulation specifically refers to the visible
green/yellow colour combination of the conductor. If the visible colours
of a conductor are green/yellow, then that 'exclusively identifies that
conductor as a protective conductor'.

However, if the exposed green/yellow conductor of a multicore cable is
fully oversheathed or sleeved in another colour (e.g. brown) at the
terminations, then IMO, the new designation for that conductor would not
contravene the regulations.

It's not that different from oversheathing the blue neutral in a switch
drop with brown sleeving to redesignate it as a live conductor.

Hang about - whilst I cannot put my finger on the reg this second, I
believe
that using a green/yellow conductor for any other purpose is absolutely
verboten.

You might be right, but I couldn't find a regulation prohibiting the
reassignment of the green/yellow conductor in a multicore cable.

I think you'll find that using the combination green/yellow *COLOUR* for
anything other than a protective conductor is 'absolutely verboten' (or
'absolutely forbidden', once the UK is out of the EU). However, reassigning
the green/yellow conductor of a multicore cable (*NOT* a single core
conductor, which is forbidden), does not appear to contravene the regs.

Reassignment of a conductor at the termination using tape, sleeving, or
alphanumeric identifiers takes precedence over the original core colour
(although it would be good practice to also oversleeve a reassigned
green/yellow conductor in a multicore cable when alphanumeric identifiers
are being used).

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

OK, over to you, then ;-)

But common sense wise - what if someone cuts the cable later, determines
an apparent CPC and bonds it to something exposed?

What, without checking/testing the 'apparent aspect of their CPC
observation? I guess the protective device/mcb/rcd will trip on
re-energisation :-)

If someone 'cuts the cable later', they should be a qualified electrician
and know what they're doing. If they are remaking the termination for some
reason, they should at least notice that the green/yellow conductor has been
reassigned at the old termination. If they're simply reusing the cable for
something else, then any previous reassignments at the terminations would be
irrelevant.


This extract is taken from an ECA Guide to the 17th Edition IEE Wiring
Regulations:

"D 3.1 Principle of required identification (514.3.1)

It is most important to understand the principle behind the drafting of the
17th Edition in respect of cable identification. Cable cores shall be
identifiable at their terminations either by colour or by alphanumeric
characters. While this has not changed from the 16th Edition it is worth
discussing the principles.

It is noted that cores should preferably be identifiable throughout their
length. For many applications coloured cables, either single- or multicore,
will be used and these cables are obviously identified throughout their
length. However, in many other applications installers will need to make
use of this Regulation (514.3.1) for overmarking at terminations. The
principles and applications of identification are now discussed with the use
of diagrams.

[sorry, can't post the diagrams]

Figure D 3.1 shows the principle of identification where colours are used,
i.e. marking by colour at all terminations and preferably throughout the
length.

In Figure D 3.1 marking throughout the length is not used and single core
cables have been used. It should be noted that the colour of the cables
originally used is not important and overmarking by tape or similar takes
precedence.

Building on this principle, Figure D 3.2 shows the principle of
identification where alphanumeric identification is used.

It is perhaps more obvious now that marking throughout the length is not
necessary. It should be noted that the colour of the cables originally used
is not important and overmarking takes precedence. This principle holds
whatever the colour of cores of the original cable, and applies at
terminations by coloured tapes or by characters.

In summary, an important principle is established in that, wherever marking
at terminations by either tapes, lettering or numbering is used, the
original cable colours must be ignored; this can be against your gut feeling
but you must get used to it!

Common examples and applications where identification is only practised at
terminations include the following:

- Multicore cables with more than five cores.
- MICC cables.
- Control applications wired in single-core conductors.
- Applications where coloured cable is not available, including
connections to large generators or transformers, where often only black
cable is available.

It should now be established that installers may wish to use any single
cable colour, or combination of colours, and overmark at terminations, and
this is not considered a lesser option. For green-and-yellow conductors in
multicore cables, overmarking in another colour at terminations is
permitted. Overmarking at terminations is prohibited for single-core
green-and-yellow conductors."

--
Interloper