Dangerous break down of cable insulation

The PVC in the cable reacts with the copper and this causes a green gunge to form. This breaks down the insulation of the cable and creates a hazard. The installation should be rewired as soon as possible to ensure the safety of the premises and its inhabitants.

We came across this recently in a house where we were asked to install solar panels.

Some cables brought Ireland in the 70’s and 80’s have a problem with insulation breakdown.