For Medical Equipment the PLUG MUST be moulded and the whole cable replaced
This is correct, in that replacing a moulded plug with a rewireable plug may be considered a modification of the medical device. However, some equipment may be supplied with a rewireable plug (e.g. Mobile X-ray), so the use of ferrules stands.
In fact, for any work related equipment (non-medical) the use of a ferrule is really mandatory. What you do at home is another matter!
