Rules regarding buried earth cables

Question

Nothing I can see in the regs differentiates between an earth cable and T&E when it comes to the rules regarding buried cables.

But what I can't work out is why it's OK to run a T&E in EARTHED conduit outside of safe zones, but NOT an earth cable, since from the perspective of a nail/screw penetrating into the wall and catching the cable or conduit - there is no difference.

AJJewsbury · Accepted Answer

I take it we're talking about cables concealed in a wall, rather than buried in the ground. 
 
 rather than against the regs I suspect. 
 
 I guess we're talking the subtleties of 522.6.204 (i) - where a thick G/Y bonding or Earthing conductor would in principle satisfy the requirement of having an earthed metallic covering (if surrounding a non-existent core), but 6491X G/Y singles comply with BS 6004 rather than any of the cable standards stated. 
 My first guess is that 522.6.204 was originally written only with cables containing live conductors in mind (it's also tied up with a requirement for 30mA RCD protection, which also doesn't make a lot of sense in some particular circumstances). 
 - Andy.

Sparkingchip · Answer

Generally it&rsquo;s fairly obvious if someone cuts through a twin and earth cable because there&rsquo;s a big flash and a bang and/or things stop working, but with an earth conductor damage may not be immediately evident, it is also less likely to get repaired. 
 So a buried earth conductor really needs more mechanical protection, not less.

Rules regarding buried earth cables

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