What I have found, is that chocolate blocs used in CFL light fittings, after a few years of service, the plastic collapses into a powder, exposing the brass ferils and are now dangerous if touched. The disintegration of the plastic is due to the UV light emitted by the CFL, and most of the chocolate blocs being sold today do not have a UV block when manufactured. It could be for this reason, that that they are not recommended in DBs and other electrical installations, which may be exposed to UV light.