ELECTRICAL
ITEC Guide to Controls
01 – December 05
WORK
PART 1
Guide to Control Panel
Cable Identification
TECHNOLOGY
MAKING
The IEE consider a possible identification scheme for panel conductors as follows:
Neutral or mid-point conductor
Where a circuit includes a neutral or mid-point conductor identified by colour, the colour used shall
be blue.
Protective conductor
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.
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 514-04-03.
In this combination one of the colours shall cover at least 30% and at most 70% of the surface being
covered, while the other colour shall cover the remained of the surface.
A bare conductor or busbar used as a protective conductor shall be identified, where necessary, by
equal green-and-yellow stripes, each not less than 15 mm and not more than 100 mm wide, close
together, either throughout the length of the conductor or in each compartment and unit and at each
accessible position. If adhesive tape is used, it shall be bi-coloured.
PEN conductor
A PEN conductor shall, when insulated, be marked by one of the following methods:
(i) Green-and-yellow throughout its length with, in addition, blue markings at the terminations, or
(ii) Blue throughout its length with, in addition, green-and-yellow markings at the terminations.
Other conductors
Other conductors shall be identified by colour in accordance with Table 51.
The single green colour shall not be used.
Bare conductors
A bare conductor shall be identified, where necessary, by the application of tape, sleeve or disc of
the appropriate colour prescribed in Table 51 or by painting with such a colour.
Identification of conductors by letters and/or numbers
The lettering or numbering system applies to identification of individual conductors and of
conductors in a group. The identification shall be clearly legible and durable. All numerals shall be
in strong contrast to the colour of the insulation. The identification shall be given in letters or Arabic
numerals. In order to avoid confusion, unattached numerals 6 and 9 shall be underlined.
Protective conductor
Conductors with green-and-yellow colour identification shall not be numbered other than for the
purpose of circuit identification.
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Alphanumeric identification of cables
The preferred alphanumeric system is described in table 51.
Numeric
Conductors may be identified by numbers, the number 0 being reserved for the neutral or mid-point
conductor.
Omissions of identification by colour or marking
Identification by colour or marking is not required for:
(i)
(ii)
(iii)
(iv)
(v)
Concentric conductors of cables
Metal sheath or armour of cables when used as a protective conductor
Bare conductors where permanent identification is no practicable
Extraneous-conductive-parts used as a protective conductor
Exposed-conductive-parts used as a protective conductor.
Identification of conductors
Function
Alphanumeric
Colour
Green-and-yellow
Cream
Protective conductors
Functional earthing conductor
..a.c. power circuit (1)
Phase of single-phase circuit
Neutral of single-or three-phase circuit
Phase 1 of a three-phase a.c. circuit
Phase 2 of a three-phase a.c. circuit
Phase 3 of a three-phase a.c. circuit
L
N
L1
L2
L3
Brown
Blue
Brown
Black
Grey
Two-wire unearthed d.c. power circuit
Positive of two-wire circuit
Negative of two-wire circuit
L+
L-
Brown
Grey
Two-wire earthed d.c. power circuit
Positive (of negative earthed) circuit
Negative (of negative earthed) circuit(2)
L+
M
Brown
Blue
Positive (of positive earthed) circuit(2)
Negative (of positive earthed) circuit
M
L-
Blue
Grey
L+
Brown
LL+
M
L-
Grey
Brown
Blue
Grey
Control circuits, ELV and other applications
Phase conductor
L
Neutral or mid-wire(4)
N or M
Brown, Black, Red, Orange,
Yellow, Violet, Grey, White,
Pink or Turquoise
Blue
Three-wire d.c. power circuit
Outer positive of two-wire circuit
derived from three-wire system
Outer negative of two-wire circuit
derived from three-wire system
Positive of three-wire circuit
Mid-wire of three-wire circuit(2)(3)
Negative of three-wire circuit
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NOTES:
(1)
(2)
(3)
(4)
Power circuits include lighting circuits.
M identifies either the mid-wire of a three-wire d.c. circuit, or the earthed conductor of a two-wire earthed
d.c. circuit
Only the middle wire of three-wire circuits may be earthed
An earthed PELV conductor is blue
BS EN 60204-1 Provides the following suggestion for the identification of conductors
General requirements
Conductors shall be identifiable at each termination in accordance with the technical documentation (see
clause 18). Annex B question 31 may be used for an agreement between supplier and user regarding a
preferred method of identification.
Where colour coding is used for identification of conductors, the following colours may be used:
BLACK, BROWN, RED, ORANGE, YELLOW, GREEN, BLUE (including LIGHT BLUE), VIOLET,
GREY, WHITE, PINK, TURQUOISE
NOTE – This list of colours is derived from IEC 60757
It is recommended that, where colour is used for identification, the colour be used throughout the length of the
conductor either by the colour of the insulation or by colour markers. An acceptable alternative may consist of
additional identification at selected locations.
For safety reasons, the colour GREEN or the colour YELLOW should not be used where there is a possibility
of confusion with the bicolour combination GREEN-AND-YELLOW (see 14.2.2).
Colour identification using combinations of those colours listed above may be used provided there can be no
confusion and that GREEN and YELLOW is not used except in the bicolour combination GREEN-ANDYELLOW.
Identification of the protective conductors
The protective conductor shall be readily distinguishable by shape, location, marking or colour. When
identification is by colour alone, the bicolour combination GREEN-AND-YELLOW shall be used throughout the
length of the conductor. This colour identification is strictly reserved for the protective conductor.
For insulated conductors, the bicolour combination GREEN-AND-YELLOW shall be such that on any 15 mm
length one of the colours covers at least 30% and not more than 70% of the surface of the conductor, the
other colour covering the remainder of the surface.
Where the protective conductor can easily be identified by its shape, position or construction (e.g. a braided
conductor), or where the insulated conductor is not readily accessible, colour coding throughout its length is
not necessary but the ends or accessible positions shall be identified by the graphical symbol 417-IEC-5019 or
by the bicolour combination GREEN-AND-YELLOW.
Identification of the neutral conductors
Where a circuit includes a neutral conductor identified by colour, the colour shall be LIGHT BLUE (see 3.1.2 of
IEC 60446). LIGHT BLUE shall not be used for identifying any other conductor where confusion is possible.
Where identification colour is used, bare conductors used as neutral conductors shall be wither coloured by a
LIGHT BLUE stripe, 15 mm to 100 mm wide in each compartment or unit or at each accessible position, or
coloured LIGHT BLUE throughout their length.
Identification of other conductors
Identification of other conductors shall be by colour (either solid or with one or more stripes), number,
alphanumeric, or a combination of colour and numbers or alphanumeric. When numbers are used, they shall
be Arabic; letters shall be Roman (either upper or lower case).
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It is recommended that insulated conductors be colour-coded as follows:
-
BLACK:
a.c. and d.c. power circuits;
-
RED:
a.c. control circuits;
-
BLUE:
d.c. control circuits;
-
ORANGE:
interlock control circuits supplied from an external power source.
Exceptions: to the above are permitted where:
-
Individual devices are purchased complete with internal wiring;
-
Insulation is used that is not available in the colours required; or
-
Multicolour cable is used, but not the bicolour combination GREEN-AND-YELLOW.
The British Standard 6231 specifies requirements for single-core non-sheathed cables, including flexible
cables, used for the wiring of switch, control metering, relay and instrument panels of power switchgear, and
for such purposes as internal connections in rectifier equipment and in motor starters and controllers.
The standard gives suggestions for cable collars as follows:
Type
Form of Conductor
Designated
temperature
Rated voltage
AU
Rigid, round, solid
700C
60 V
AK
BR
BU
BK
CR
CU
CK
0
60 V
0
600/1 000 V
0
600/1 000 V
0
600/1 000 V
0
600/1 000 V
0
600/1 000 V
0
600/1 000 V
70 C
Flexible
Rigid, round, stranded
70 C
70 C
Rigid, round, solid
70 C
Flexible
Rigid, round, stranded
90 C
90 C
Rigid, round, solid
90 C
Flexible
Types AU and AK PVC-insulated cables
Tinned annealed copper conductor
Type AK 0.75 mm2 only:
All other cables:
PVC insulation type TI 1;
PVC insulation type 2
Colours
Single colours
Black, blue, brown, cream, green, grey, orange, pink, red, turquoise, violet, white, yellow
Bi-colours
Brown/blue, Green/black, green/blue, green/brown, green/red, grey/blue, grey/brown, grey/green,
grey/orange, grey/red, orange/black, orange/blue, orange/brown, orange/green, orange/red, red/black,
red/blue, red/brown, white/black, white/blue, white/brown, white/green, white/grey, white/orange,
white/red, white/violet, white/yellow, yellow/green, yellow/violet
Types BU and BR PVC-insulated rigid cables
Plain annealed copper conductor
PVC insulation type TI 1
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Colours
Single colours
Black, blue, brown, grey, red, white, yellow
Bi-colour
Green/yellow (for earthing or similar protection, see 6.3)
Type BK PVC-insulated flexible cables
Tinned or plain annealed copper conductor
PVC insulated type TI 1
Colours
Single colours
Black, blue, brown, grey, red, white, yellow
Bi-colour
Green/yellow (for earthing or similar protection, see 6.3)
Type CK PVC-insulated flexible cables
Tinned or plain annealed copper conductor
PVC insulation type TI 3
Colours
Single colours
Black, blue, brown, grey, red, white, yellow, orange, pink, violet, turquoise, green and cream
Bi-colour
Green/yellow (for earthing or similar protection, see 6.3)
Types CU and CR PVC-insulated rigid cables
Plain annealed copper conductor
PVC insulation type TI 3
Single colours
Black, blue, brown, grey, red, white, yellow, orange, pink, violet, turquoise, green and cream
Bi-colour
Green/yellow (for earthing or similar protection, see 6.3)
BS EN/IEC 60439-1 gives the following guidance on cable colours
Identification of the protective conductor (PE, PEN) and of the neutral conductor (N) of the main
circuits
The protective conductor shall be readily distinguishable by shape, location, marking or colour. If identification
by colour is used, it must be green and yellow (twin-coloured). When the protective conductor is an insulated
single-core cable, this colour identification shall be used, preferably throughout the whole length.
NOTE: The green/yellow colour identification is strictly reserved for the protective conductor.
Any neutral conductor of the main circuit should be readily distinguishable by shape, location, marking or
colour. If identification by colour is used, it is recommended to select a light blue colour.
The terminals for external protective conductors shall be marked according to IEC 60445. As an example see
graphical symbol
No. 5019 of IEC 60417. This symbol is not required where the external protective
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conductor is intended to be connected to an internal protective conductor which is clearly identified with the
colours green/yellow.
Identification of the conductors of main and auxiliary circuits
With the exception of the cases mentioned in 7.6.5.2, the method and the extent of the identification of
conductors, for example by arrangement, colours or symbols, on the terminals to which they are connected or
on the end(s) of the conductors themselves, is the responsibility of the manufacturer and shall be in
agreement with the indications on the wiring diagrams and drawings. Where appropriate, the identification
according to IEC 60445 and IEC 60446 shall be applied.
While every care has been taken to ensure the accuracy of the information contained in this leaflet, neither the
authors nor the publishers can accept liability for any inaccuracies in or omissions from the information provided or
any loss or damage arising from or related to its use.
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