- Reaction score
- 4,325
A thought - look for signs of green verdigris on bare copper sheathed MICC caused by dampness and made worse by the combination of damp and lime cement. The outer copper sheath may have split/have holes in it leading to the magnesium oxide absorbing moisture - and then the occurrence of some 'low level' arcing and tracking when the cable is energised. The same thing can sometimes happen if bare copper MICC is in contact with damp wood - most wood is naturally acidic.