https://www.gutefrage.net/frage/deckenlampe-was-macht-man-mit-dem-erdungskabel-wenn-die-lampe-keine-erdung-will "Yes, this is quite normal, then the lamp corresponds to protection class II ..... In this case, the green/yellow wire is simply rolled up and inserted into the lamp housing.... In the case of lamps with metal housings, the green/yellow wire is usually screwed to the housing.... (but there is then a screw with the earthing symbol).