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My company manufactures medical weight scales, which are typically powered by the AC mains, and are of an all metal construction. These products are manufactured to meet IEC60601 with appropriate spacings and insulation, along with a protective earth connection between the metal enclosure and the mains power cord. Both the patient and the practitioner can come in contact with the metal enclosure and its related structure.
I'm confused as to whether the secondary electrical circuit common can be directly connected to the metal enclosure under the medical standards. This is a low voltage circuit, < 12 VDC, which is fully isolated by a step down transformer from the AC mains and poses no hazard from shock or leakage.
Due to IEC requirements to meet EMI immunity and emissions, it is desirable to connect the enclosure to the secondary circuitry common so it provides an effective shield.
I'm confused as to whether the secondary electrical circuit common can be directly connected to the metal enclosure under the medical standards. This is a low voltage circuit, < 12 VDC, which is fully isolated by a step down transformer from the AC mains and poses no hazard from shock or leakage.
Due to IEC requirements to meet EMI immunity and emissions, it is desirable to connect the enclosure to the secondary circuitry common so it provides an effective shield.