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EQUIPMENT CLASSIFICATION - Coggle Diagram

- - - - The method of protection against electric shock
        in the case of class II equipment is either double
        insulation or reinforced insulation.
      - In double insulated equipment the basic protection
        is afforded by the first layer of insulation.
  - - - Class III equipment is defined in some equipment standards as that in which protection against electric shock relies on the fact that no voltages higher than safety extra low voltage (SELV) are present.
      - In practice such equipment is either battery
        operated or supplied by a SELV transformer.
    - - Similarly, equipment powered from a SELV transformer should be tested in conjunction with the transformer as class I or class II equipment as appropriate.
    - - All medical electrical equipment that is capable of mains connection must be classified as class I or class II
  - - - Class I medical electrical equipment should have fuses at the equipment end of the main supply lead in both the live and neutral conductors, so that the supplementary protection is operative when the equipment is connected to an incorrectly wired socket outlet.
    - - A case that appears to be plastic
        does not necessarily indicate that the
        equipment is not class I
    - - Class I equipment has a protective earth
        
        The basic means of protection is the
        insulation between live parts and exposed
        conductive parts such as the metal enclosure
        
        In the event of a fault that would otherwise cause an exposed conductive part to become live,
        the supplementary protection (the protective earth)
        comes into effect
        
        A large fault current flows from the mains part to earth via the protective earth conductor, which causes a protective device in the mains circuit to disconnect the equipment from the supply.
        
        It is important to realise that not all equipment having an earth connection is necessarily class I
- - - - The applied part is insulated from the equipment (no connection to earth)
      - External application to the patient,
      - higher-quality protection against electric shock than in insulation class B
      - Not suitable for direct application to the heart
  - - - The applied part is insulated to a high level from the equipment (no connection to earth)
      - Suitable for direct application to the heart
      - External and intra cardiac application to the patient
  - - - The applied part is connected to earth
      - External application to the patient
      - Provides protection against electric shock by
        taking into account the fault current
      - Not suitable for direct application to the heart