Ground stud requirements on our medical device in IEC 60601

M

mouse7

Hi all, appreciate your clarification on this point.
I cannot find a requirement for a ground stud on our medical device in 60601. Our chassis is plastic, do we need to add a ground stud just for testing purposes?
If we don't have a ground stud, how will leakage tests be conducted?

Thanks!
 

Pads38

Moderator
Medical electrical equipment (MEE) may be Class II - double insulated. As such they would not have a 'Protective Earth' and would not be fitted with a ground stud.

(MEE for home healthcare settings is required to be Class II).

To measure leakage currents - for enclosure leakage (Touch Current) the measurement is taken between ground and foil applied to the outside of the enclosure. The size of the foil represents an adult open hand (or bigger if risk analysis demands). The foil is moved around the enclosure to find the 'worst case' positioning.

Internally powered MEE is not tested for Touch Current unless you have SIP/SOP.

The other tests are done in similar ways - using foil on the outside of the enclosure or insulated applied parts.
 

phase90

Involved In Discussions
Along the same lines, if you have a product that is Class I with a plastic enclosure, does it need a ground stud?
 

Pads38

Moderator
Along the same lines, if you have a product that is Class I with a plastic enclosure, does it need a ground stud?

Assuming that you are thinking of an external ground stud, then I would suggest that, no you do not have to have one.

However, electrical equipment, especially medical devices, are routinely tested often by a hospitals own engineering / equipment management service. A key test that they will try to do is earth bond integrity. If they cannot find a suitable earth point they may attempt to use something like the metal shell of a connector. As this test is usually done with 25 amps of current it would likely cause damage if that current was passed through unsuitable conductors, such as a PCB trace.

But if you provide an external earth point, with strong bonding then the test is easy to complete and no damage is caused.

As with just about everything in this game it's all down to risk analysis.
 
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