Has anyone out there come across Green Goo recently, and how big a hazard is it? Should an area be re-wired immediately for example or can it be managed? The green goo in question is located in a secondary school classroom. Thanks for your time everyone.

I came across this many years ago and as I recall it is something to do with a reaction between the copper in the conductor and the insulation and/or lubricant - copper thaylate rings a bell; apparently the same thing happens to copper or copper based coin collections stored in pvc wallets. Paul/Zimmy may have a view but I would suspect that 'managing' (I assume you mean 'leave it') is unlikely to be a long term solution as I believe that there is a risk of the conductor becoming exposed and coming into contact with the earth - or something along those lines.