N2XCH Cable?

[vinchii]

Hi fellow Electrical practitioner. I had encounter this N2XCH cables and the like for a European project. As observed, There's this size descried as i.e N2XCH 4x25/16 mmsq. where 16mmsq is a concentric copper conductor.

My question is. What is the purpose of this Concentric copper conductor in this type of Cable?

 

[7anoter4]

In my opinion the concentric conductor is used for common neutral and earthing system TN-C [P.E.N conductor] as per BS7671 or IEC 60364-1

https://www.tlc-direct.co.uk/Book/5.7.1.htm