Hamish Anderson said:

What is interpreted from wiring regulations on BS7671 Section 514.3.2? Do all cables essentially need to have a cable identification label a the core?

Only at terminations for the function but not the circuit (or cable) identification ... but preferably thought the length. A single-core cable, however, could be identified at the sheath and/or the insulation. See Reg 514.3.2.

Hamish Anderson said:

Or is the colour of the cable itself the identification for example brown as live? Or should this be labelled? Say the cable is called "P001" and the live should have to be labelled as "P001-L1"?

Regulation 514.3.2 only requires identification of the function of the core in terms of electrical hazard, i.e. Line (be that L1, L2 or L3), Neutral, Protective Conductor, etc. as per Regulation 514.3.1. As per Reg 514.3.1, the identification does not have to be by colour, but could be by either alphanumeric scheme shown in Table 51, or alternatively if the cable has numbered black cores for live conductors, just the number can be used.

The circuit number or cable number (not specifically required by BS 7671 to be applied to the cable itself, but useful particularly in large or complex installations) can be applied to the cable as a whole, rather than "per core".

So, whilst the cable sheath might have 'P001' applied, the conductor still only needs to be identified by colour, 'L1' (in this example), or by the number of a numbered multicore cable.

If cable numbers were to be applied to single core cables would, perhaps it could be asserted by definition, effectively have the cable number as well as the function, and in this case, if the circuit or cable number were applied, I'd expect to see 'P001-L1' (as per your example).

Hamish Anderson said:

What is interpreted from wiring regulations on BS7671 Section 514.3.2? Do all cables essentially need to have a cable identification label a the core?

Only at terminations for the function but not the circuit (or cable) identification ... but preferably thought the length. A single-core cable, however, could be identified at the sheath and/or the insulation. See Reg 514.3.2.

Hamish Anderson said:

Or is the colour of the cable itself the identification for example brown as live? Or should this be labelled? Say the cable is called "P001" and the live should have to be labelled as "P001-L1"?

Regulation 514.3.2 only requires identification of the function of the core in terms of electrical hazard, i.e. Line (be that L1, L2 or L3), Neutral, Protective Conductor, etc. as per Regulation 514.3.1. As per Reg 514.3.1, the identification does not have to be by colour, but could be by either alphanumeric scheme shown in Table 51, or alternatively if the cable has numbered black cores for live conductors, just the number can be used.

The circuit number or cable number (not specifically required by BS 7671 to be applied to the cable itself, but useful particularly in large or complex installations) can be applied to the cable as a whole, rather than "per core".

So, whilst the cable sheath might have 'P001' applied, the conductor still only needs to be identified by colour, 'L1' (in this example), or by the number of a numbered multicore cable.

If cable numbers were to be applied to single core cables would, perhaps it could be asserted by definition, effectively have the cable number as well as the function, and in this case, if the circuit or cable number were applied, I'd expect to see 'P001-L1' (as per your example).