Diagonal cables from hell?

[Andy Burns]

[ARW]

Any ideas why is he using metal capping?

[Fredxx]

Why not? It's very good protection against standard or hammer drills.

[harry]

IME any sort of drill will go straight through metal capping as if it wasn't there.

[PeterC]

Well, there is a delay but, more importantly, there's clear warning whne the drill hits the metal (based on 70 yo capping that's probably thicker than modern stuff).

[Andrew]

Don't you need 3mm steel to protect meter tails if, for example a Wylex metal box in the party wall was origianl (and cant be removed) but a new CU is located above, to the side, up and over to the opposite wall, or wherever.

[Mike Clarke]

But easily penetrated by the nail of a picture hook.

Not actually BTWTTS but have fixed 2 instances of this happening.