A friend asked me to look at his house wiring because green stuff was oozing out of L & N at most of the 13A sockets in the house. He wasn't kidding - it's like Lyles Golden Syrup, but bright green instead of golden. It is *not* corroding the copper wires at all, but the brass pins of 13A plugs are blackened. The wiring and house are about 25 years old, dry and in vg condition, standard 7/029 T&E. The effect was first noticed about 5 years ago. Earth wires are clean, except where some goo has dripped on them. Insulation is fine - over 100M on the circuit I tested. Stripping back a bit of neutral insulation, the goo appears to be in the strands.
Any ideas?