Cables in metal capping.

Thin galvanised metal capping does not need to be earthed. In fact if the cables are installed within safe zones and the circuits are RCD protected there is no need for any capping or conduit at all and cables can actually be laid direct in the chase and plastered over.

If your cable is a thermoplastic twin and earth cable and is run along approved cable routing it does not need metal capping. If protected by RCD however, you need to make provision for heat dissipation - which is where your metal or plastic capping comes into play. However, if your cables are not RCD protected, then they need to be 50mm deep and or contain in earthed metal conduit or trunking which. You would only need an earthed metal conduit or trunking (not metal capping which will not prevent penetration of nail or screws) capable of preventing screw or nail penetration if your kitchen wall was mainly metal frame wall. CIVIl Electrical Services

Hmmm there is some absolute tosh on this one.... You CAN bury cables less than 50mm without an RCD IF, and only IF, the required metal protection is earthed. It has nothing to do with nail penetration. This earthing ensures automatic disconnection of supply by ensuring that a nail going into the line conductor only, will also be earthed by the metallic protection. That was not a spelling mistake, Line is the 240V live conductor, the other live conductor being the Neutral. If you have an RCD protecting this circuit you do not need to mechanically protect cables that are buried less than 50mm. Capping is typically only used to protect whilst plastering.

Hello Brian Metal capping in use to protect cable while plastering walls. It is not earthing required and circuit in wall less than 50mm depth must be protected by RCD or RCBO what you already have. Hope it'll help. Vadims

There is no requirement to earth metal capping buried in the wall as it is not an exposed conductive part or an extraneous conductive part. I have seen people do it in the past so maybe it used to be in a previous edition of the regs.