I am struggling with some requirements relative to interconnecting equipment and EN60950. My question is generic but I thought the example of an RS232 comport on a PC would highlight my questions as to - "what is reasonable or required for warnings to the user relative to connection to other equipment".
Background EN60950 has the following sections: Section 2.10.1 states - "Where equipment is intended to be electrically connected to other equipment interconnection circuits shall be selected to provide continued conformance with the requirements of 2.3 for SELV circuits, and with the requirements of clause 6 for TNV circuits, after making connections between equipment." Section 1.7.2 Safety Instructions - "If it is necessary to take special precautions to avoid the introduction of hazards when operation, installing, maintaining , transporting or storing equipment , the manufacturer shall have available the necessary instructions." Safety relationships of an RS232 port (as I understand them) 1) The RS232 port is a SELV circuit as an extension of the 12 or 5 Volt secondary of the PC power supply. 2) The RS232 port is referenced to protective earth through the PC power cord. 3) The RS232 port is not typically galvanically isolated. 4) The RS232 port could be connected to a product that is not IEC950 qualified. Questions: 1) Are any warning symbols required at this port such as a yellow triangle with an exclamation mark inside? 2) Is there any requirement to warn the user not to connect to any other equipment that would violate the SELV nature of this circuit? 3) When I have reviewed CE marked PCs there does not appear to be much addressing this example or any related example. It appears that they are relying on : 3a) Requirement that local safety codes be followed 3b) Clear definition of the port. Is this adequate? Summary I am struggling with the conflicts of "due diligence" in following the standards and not wanting to appear overly restrictive relative to our competitors. If you have any guidance in this or related examples I would very much like to here your war stories. Regards Chris Wells Sr Des Eng. Cutler-Hammer Pittsburgh, Pa, USA ph 1 (412) 494-3723 wellscd @ch.etn.com
