Can any underground system be made a Cat C system?

[JamieP]

Can any underground system be made a Cat C system? Or only those specified in Table 3.5?

[AlecK]

As for your other query; look at the relevant clause rather than just the Table.
Cat C is defined in both 3.11.2 (para 5) and 3.11.3.3.
Any type of wiring system that's installed chased in rock and covered in concrete meets the definition;
however, as per 3.11.2 para 6, the cable type must be one of those listed in the Table as permitted for the intended category.
So only 3 cable types can be used as Cat C.

I think of Cat C as an Exception to the normal choices of Cat A or B.
It's for when the required depth can't be achieved, so
- the depth requirements (both cable and warning strip) are relaxed;
- cable type is restricted; and
- specific additional protection is required