Ok, I must have misunderstood, i thought we were talking about overhead supplies here. The OP was talking about OH and so i have continued in that same area. I have never seen an underground supply that is TT unless the incoming earth has been lost at the joint underground. I would not expect a DNO to replace its cables underground just to implement PME, and i have not experienced a TNS service converted into PME without the service being replaced. In my areas if a TNS service is moved within a property they leave it as TNS and do not convert it to PME
I was not talking down soldered joints or connections, and yes i agreee there are many that are still in service and will be for years. However most DNO have moved over to crimp or more accurately shear off connections because of time and cost factors, but also they have a lower failiure rate than soldered joints. Now before everyone gets on thier soap box, i am not saying this is my point of view but that of the DNO i worked for and the jointers and linesmen who were using them on the cables that i spoke to and asked about it.
It was also the policy of SSE at one point that they would replace the old bare conductors with an insulated bundled service wherever possible, and then use concentric down to the head. If the main OH service was not easy to replace they would still replace the bare conductors into the property with concentric and when it was connected to the existing OH main Shearoff would be used. That would replace all connections along the length of the main; once all services had been connected, it would be staked down and labeled as PME.
