dennis@home wrote:

"BigWallop" wrote in message
om...

[snip]

The capping is also better detected by devices meant to check the area
you
are about to drill into. No one said it protects the cabling from
nuclear attack, but it does offer enough protection from someone banging
a nail through it.

No it doesn't.
Masonry nails are hardened steel and will just go straight through.

I agree with Dennis there. A while ago I needed to re-route a length of old
cable covered by metal capping under plaster. As I excavated plaster along
it's length I could see it was heading ominously for a picture hook on the
wall. Sure enough the pin for the hook had been hammered in straight
through the metal capping and the cable. Subsequent examination of the
cable showed that the pin went straight through the live conductor of the
old 7/.029 T&E with 4 strands one side of the pin and three the other. The
odd thing is that it had been like that for years without causing any
trouble.

--
Mike Clarke