Why do medical devices need 2xMOPP?

Also see: Does 2xMOOP / 2xMOPP require two separate converters / layers of isolation?

For medical devices the IEC60601 norm specifies more stringent requirements for electrical safety like the 2xMOPP requirement (MOPP = Means of Patient Protection). Many developers wonder why the requirements are different to other types of devices like consumer devices.

• It is assumed that patients might already have impaired health and hence any additional damage caused by e.g. a malfunctioning medical device might have greater consequences than in healthy patients.
  • For example, assume that a patient with a severe infection receives a light  electric shock from a malfunctioning infrared thermometer. While the electric shock is unrelated to the original injury of the patient (i.e. the infection), having to treat both issues might be much harder than just treating the infection: For example, the infection might spread to the body part where the electric shock occured, or the additional inflammation due to the electric shock might contribute to the deteriorating health of the patient
• Additionally, if a patient receives e.g. an electric shock from a medical device, many patients will not trust medical devices - and potentially even the entire medical system - any more, resulting in less capability of treating those patients.
  • Imagine if you would receive a small, unpleasant (but not in any way dangerous) shock every time you use a thermometer to measure fever. Most people would refrain from measuring their temperature when they are ill in order to avoid the impleasant shock. This will lead to many patients being diagnosed at a later stage of their disease which would in turn impede the treatment.
• Furthermore, it is assumed that the medical device will be used under circumstances like pandemics, where any additional injury will unneccessarily consume medical resources such as hospital beds and keep medical personnel from treating potentially more serious injuries.