BS 6004:2012 pdf download – Electric cables – PVC insulated and PVC sheathed cables for voltages up to and including 300/500 V, for electric power and lighting
8 Identification of cores
8.1 General The cores of all cables shall be identified by colour. Each core shall be identified by its colour as indicated in Table 3 to Table 6.
NOTE Other colours may be used by agreement with the manufacturer; in this case the requirements in 11.2 do not apply.
8.2 Core colours
The colour shall be applied throughout either the whole insulation or the outer cohesive layer and shall be applied as part of the extrusion process.
The insulation of the coloured cores, irrespective of the method of colouring, shall be tested as a complete single layer (see 7.2). The colours of the cores, determined by the number of cores in the cable, and also the sequence of the colours shall be as given in Table 3 to Table 6.
Where alternative colours are used (see 8.1, Note), the sequence shall be agreed with the manufacturer. On a core with the bi-colour combination of green-and-yellow, the distribution of these colours shall be such that for every 15 mm length of core one of these colours shall cover not less than 30% and not more than 70% of the surface of the core, while the other colour shall cover the remainder of the surface. Conformity shall be checked by measurement.
NOTE 1 In cases of dispute regarding the green-and-yellow combination, and where appropriate to the method of colour marking of the insulation, a suitable test method for checking conformity is given in BS EN 50396, 5.2.
NOTE 2 It is understood that the colours green and yellow, when they are combined as specified, are recognized as identifying exclusively the core intended for use as an earth connection or similar protection. The colour blue is for the identification of the core intended to be connected to neutral but, if there is no neutral, blue may be used to identify any core except for the earth or protective conductor.
NOTE 3 Depending on where the cables are used, restrictions may apply to the use of certain colours for some applications.
8.3 Clarity and durability The colour used for core identification shall be clearly identifiable and durable such that it cannot be removed when tested in accordance with BS EN 50396, 5.1.
9 Multi-core circular cables The cores of the 2-core, 3-core, 4-core and 5-core circular cables shall be laid up together. Cores shall be laid up in the sequence of colours as given in Table 6. If alternative core colours to those specified in Table 6 are used, then an alternative sequence shall be agreed with the manufacturer. Conformity shall be checked by visual examination. The maximum length of lay for circular cables shall be not more than 25 times the diameter of the assembly of laid up cores. Conformity shall be checked in accordance with 15.5. 10 Sheath 10.1 Type of sheath The sheath shall be an extruded layer of PVC of one of the following types, in accordance with Table 3 to Table 6:
• Type 6 as specified in BS 7655-4.2.
• Type 10 as specified in BS 7655-4.2.
10.2 Application The sheath shall be applied by an extrusion process. NOTE The sheath can be applied in a single layer or in a number of cohesive layers. Where more than one layer is used, all testing specified in this British Standard shall be carried out on the complete sheath as though it were a single layer of the declared sheath type (see 10.1).
When the sheath is removed, there shall be no damage to the core insulation when visually checked. 10.3 Thickness When measured in accordance with BS EN 50396, 4.2 or 4.3, as applicable, the smallest value , t m , of the radial thickness of the sheath shall not fall below 85% of the value given in Table 3 to Table 6 by more than 0.1 mm, i.e.: