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RE: [802.3af] IEE802.3af and IEC60950 - safety issues

First off, you should purchase the latest Draft, D4.2. It references EN60950-1:2001, although only to supply the definition of Limited Power Source, and test methodologies for determining isolation voltages. P802.3af is not a product safety specification. Many 802.3af products may not be, for example, ITE equipment, but may fall under other safety standards such as UL508 for industrial controls.
If you do not have a copy of the full 802.3-2002 standard, it may be downloaded free of charge from the IEEE SA website at:
You should read this to understand the way isolation is specified in 802.3 if the terms Environment A and Environment B are unfamiliar. P802.3af does not address any of the issues you cite in your item 2, since these are beyond the scope of the draft. P802.3af does not address the primary power supply, only the output characteristics of the PSE. Primary power and applications space are implementation specific, and you must determine which elements of EN60950 apply to your application. Language within 802.3af makes it clear that products must comply with all local and national codes that are applicable to the product, and that such compliance is beyond the scope of the draft.
The 802.3af draft gives the PD designer the information necessary create the interface to a PSE. Any other issues are implementation-specific and out of scope.

Steven B. Carlson
Co-Chair, ESTA Control Protocols Working Group
Chair, ESTA ACN Task Group
Chair, IEEE 802.3af DTE Power via MDI Task Force
Secretary, IEEE 802.3 CSMA/CD Working Group
High Speed Design, Inc.
11929 NW Old Quarry Road
Portland, OR 97229
FAX 503.626.4206

-----Original Message-----
From: owner-stds-802-3-pwrviamdi@xxxxxxxxxxxxxxxxxx [mailto:owner-stds-802-3-pwrviamdi@xxxxxxxxxxxxxxxxxx]On Behalf Of Charles Palmer
Sent: Thursday, March 27, 2003 5:30 AM
To: stds-802-3-pwrviamdi@xxxxxxxx
Subject: [802.3af] IEE802.3af and IEC60950 - safety issues

Hi Team
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?
Many Thanks
Regards -
Charles Palmer
Technical Director, DSP Design Ltd
email: charles@xxxxxxxxxxxxx
7 Tapton Park Innovation Centre, Brimington Rd, Chesterfield S41 0TZ, UK
ph: +44 (0) 1246 545 918