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The current draft is P802.3af/D4.2. There were significant edits to subclause 33.4.1 in D4.1 (though they do not include everything you wish was there). I recommend you work from a current version of the draft and continue to look for new drafts until the work is complete. As the cover of the draft states it is "subject to change".
From: Charles Palmer [mailto:charles@xxxxxxxxxxxxx]
Sent: Thursday, March 27, 2003 5:30 AM
Subject: [802.3af] IEE802.3af and IEC60950 - safety issues
I am trying to design a PD power supply, armed with IEEE802.3af/D4.0 and EN60950-1:2001. In particular, I am struggling with the requirements of isolation between the Ethernet cable and my low voltage circuitry. Can I trouble someone for assistance?
1 The 802.3af spec (section 33.4.1, Isolation) refers to IEC 60950 section 5.3.2. My copy of EN60950 section 5.3.2 is about fault conditions for motors. Does the 802.3af spec mean section 5.2.2? Or does EN60950 differ from IEC60950?
2 I am new to EN60950. I had hoped for guidance in the 802.3af spec on issues such as creepage and clearance distances, types of insulation etc. It appears that I may need to know whether my PSU is an SELV, TNV-1, TNV-2 or TNV-3; whether I am working under Pollution Degrees 1, 2 or 3; what my Working Voltage is; what class of insulation I need; and so forth. The spec seems to say that the 802.3af power is neither an AC Mains Supply nor a DC Main Supply (since power is through the Telecommunications Network wiring). Help! Can someone who has worked through this provide some pointers?
I know you don't want to change the spec at this stage, but are you sure there is enough information in the spec to answer these questions and allow compliant PD equipment to be designed?
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