Earthing metal capping?

[captaincargo]

Example...

Light switch cable drop from a ceiling down a wall to a recessed metal back box ive protected the cable with a length of metal capping, new regs state even in a `safe zone` metal capping will need to be earthed.
QUESTION...

1.How do you earth metal capping? Is it simply relied upon that the backbox is touching the capping and the cpc attached to the earth terminal in the backbox gives the continuity needed?

2. After the metal capping is plastered over so you cant see it anymore how can ,in future tests,you prove the capping is earthed? that continuity between the back box and the capping is still achieved?

 

[Spark123]

Regs don't state metal capping needs to be earthed. The purpose of metal capping is to protect the cable from damage from the plasterers trowel.
BS7671:2008 requires cables run <50mm deep in the safe zones to be RCD protected. <50mm deep outside the safe zones they need to be in a metal conduit, trunking, have an earthed metallic sheath or have additional protection to prevent a screw or nail hitting the cable.

 

[captaincargo]

Cheers Spark
I must have misread an article in my NIC update
I thought it said 2008 regs now require cabels run in safe zones below 50mm depth and from a drop above to an outlet need to be RCD protected AND need to be protected by earthed conduit,trunking or sheath.

 

[dingbat]

...need to be protected by earthed conduit,trunking or sheath.

"... satisfying the requirements of these Regulations for use as a protective conductor..."

Capping has never satisfied the requirements... despite the many, many times that sparks have argued over the need to earth it.

 

[Katron]

thought it said 2008 regs now require cabels run in safe zones below 50mm depth and from a drop above to an outlet need to be RCD protected AND need to be protected by earthed conduit,trunking or sheath.

If the cable is mechanically protected then doesn't need to be rcd protected, but if clipped in depth of less than 50mm then needs to be on rcd, even when in safe zones.