Nice simple job I had , add 2 extra sockets in a 1970's house installed the sockets , the tested ,then opened the can of worms the install was one ring 10 sockets , out of the 10 1 had an earth tails out Ring tests all open circuit so started to work from the one socket , open circuit readings on the cpc , floor up located cable and re tested open circuit replaced cable cable cpc had broken half way down , new leg test no earth at the next socket open circuit on cpc skirting board nail through the cable , replaced test next socket other side of the wall no earth open circuit on cpc , yep skirting board nail through the cable , next socket no earth , open circuit readings on cpc L and N , not so easy to replace as it was in the kitchen , cupboard fixing screw through cable in 2 places , replaced leg , next socket open circuit readings no earth , return leg 3 holes through cable one filled with cement , replaced both legs , next socket ok but no continuity on ring located loose live and neutral , open circuit on cpc , found damaged cable , still no continuity on cpc's , located a junction box under the floor cpc's cut off fixed and all continuity's ok virtually rewired the ring !!! had a new consumer unit 10 years ago but had the RCD replaced with a main switch , i wonder why ,, obviously no testing had beed carried out as the original skirting board nails were through the cables and hole that were drilled into the cables were from the original kitchen so looking at it 40 years with no earth on the sockets nice 10 hours of fault finding and repairs to put it right !!!