RCD & cable mechanical protection

Good morning everyone.

I have couple of questions for the more experienced.

1) In order to get away from an RCD (assuming that the circuit does not feed a socket...) you need mechanical protection for cables chased in the wall at less than 50mm.

Does this mechanical protection need to be earthed as well if we assume that the cables will be protected by galvanized steel conduit???

Or just the steel conduit is enough?

2) I know that a SWA cable is considered mechanical protected by the SWA. Does the SWA need to be earthed? What if I use an external CPC and do not connect the SWA to earth. I guess this is the same question as question number #1...

3) I have a cable from PRYSMIAN called AFUMEX LSX BS8436 and in the description it states:

    "Independently assessed by ERA for nail penetration tests (1.5mm2 to 2.5mm2)"

     Does this make this cable mechanically protected like a SWA cable? Do I understand it correctly?

.....

Thanks for your time guys

Kind Regards

Apostolos