Applied Part: Type B, BF or CF

IEC 60601-1 uses the term applied part to refer to the part of the medical device which come into physical contact with the patient in order for the device to carry out its intended function.

Applied parts are classified as Type B, Type BF or Type CF according to the nature of the device and the type of contact. Each classification has differing requirements from the point of view of protection against electrical shock.

Type CF is the most stringent classification, being required for those applications where the applied part is in direct conductive contact with the heart or other applications as considered necessary.

Type BF is less stringent than CF, and is generally for devices that have conductive contact with the patient, or having medium or long term contact with the patient.

Type B is the least stringent classification, and is used for applied parts that are generally not conductive and can be immediately released from the patient.

iype B applied parts may be connected to earth, while Type BF and CF are 'floating' and must be separated from earth.
...
Applied Part

A part of the equipment which in normal use:

necessarily comes into physical contact with the patient for the equipment to perform its function; or
can be brought into contact with the patient; or
needs to be touched by the patient
....
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Protecting the patient & operator
Exposure to even small leakage currents can have an adverse effect on the well being of hospital patients. The “allowed leakage current” from the end-product medical equipment (not the power supply alone) can vary from a few µA to a few hundred µA. Obviously, medical equipment that has direct physical contact with patients must limit their leakage current to the lowest prescribed levels.
Medical equipment is classified according to the applied parts as follows:

Type B: A type B (Body) applied part is one which, although it can deliver a current to the patient, is not intended to do so as part of its function (e.g., automated pill dispensers at nurses’ stations, operating room lights).

Type BF: The BF (Body Floating) applied part has a patient connection which is designed and intended to deliver electrical energy or an electrophysiological signal to or from the patient (e.g., ECG equipment).

Type CF: The CF (Cardiac Floating) applied part has a patient connection which is designed and intended to deliver electrical energy or an electrophysiological signal to or from the patient and is specified as being suitable for direct cardiac application (e.g., external pacemakers).
[http://www.epdonthenet.net/article/25890/Selecting-power-sup...]

4.4 Equipment types
As described above, the class of equipment defines the method of protection against electric shock. The degree of protection for medical electrical equipment is defined by the type designation. The reason for the existence of type designations is that different pieces of medical electrical equipment have different areas of application and therefore different electrical safety requirements. For example, it would not be necessary to make a particular piece medical electrical equipment safe enough for direct cardiac connection if there is no possibility of this situation arising.

Table 1 shows the symbols and definitions for each type classification of medical electrical equipment.
Type Symbol Definition
-- B Type B
Equipment providing a particular degree of protection against electric shock, particularly regarding allowable leakage currents and reliability of the protective earth connection (if present).
-- BF Type BF
As type B but with isolated or floating (F - type) applied part or parts.
-- CF Type CF
Equipment providing a higher degree of protection against electric shock than type BF, particularly with regard to allowable leakage currents, and having floating applied parts.

[http://www.ebme.co.uk/arts/safety/part4.htm]