That is currently the only information I have. I traced all the low, resistance faults to the cables buried in the floor. My initial suspicion fell on possible damage to cables caused by work carried out after the original installation was finished.However after carrying out IR tests It quickly became clear that all cables buried in the ground were affected. I had never ecountered a similar situation before so I started asking around. Eventually I got some feedback from a sparks organisation I am a member of (ECSSA). They preceded RECI. They informed me they have being notified of several cases involving concrete from the same time period.Can you tell me exactly what has happened, retarders do not normally have an adverse effect on buried service's, this all sounds a bit off to me.
Obviously digging up the floor would be conclusive proof but that is not an option