Over the past few years I have inspected several households whop have reported that their sockets and in some case, light fittings ooze a green oily substance or goo, similar in colour and appearance to washing-up liquid.
So what is this?
On safe removal of the electrical fitting, it is likely the cables will look similar to those in the pictures below, with similar coloured staining run out of the socket pin-holes and possibly down the wall it is affixed to. This is considered to be a relatively inert, non-conductive substance that has little bearing on the performance of the cable other than the unfortunate residue it leaves behind. It is a result of the copper conductor reacting with the plasticiser in the cable insulation, promoting a released of the a chemical known as degraded di-isoctyl phthalate. Whilst it doesn’t necessarily pose a risk to the homeowner, it should not be ingested and contact with the skin should be avoided.
Most electricians will be happy to conduct a test on the cable and insulation to establish it’s relative condition and in most cases does not necessitate a rewire unless the green discharge has become unacceptable to the homeowner or the cable is found to be unsafe.