"The reason they do not incorporate the sheathing on the CPC is to allow it to do it's job within the cable. The CPC sits right against the live and neutral conductors, if the cable gets damaged damaging the sheathing of the L/N conductors the idea is that the electricity will go straight to earth and activate the circuit protection."
"Used when putting a ring main into the garage - it does what it says on the tin. Doesn't split like some of the others I have used. Just a pity that I now have about 99 metres of the stuff left over."