The isolation is handled by: a) transformer
AND b) clearance/dielectric between "ground" and the nets that connect between the connector and the transformer. On the practical side, 5 mil of FR4 is enough to provide isolation in inner layers, and min of about 50-75 mil on the ouoter layers. The moat under transformer has nothing to do with it. Neven > > > Not for safety, sorry the 802 reference was from the IEEE 802.3 > Ethernet > standards. I forget which section but there is a section on the electrical > characteristics for the port and the wiring. Unless its been changed there is > 1500 v isolation requirement between signals and chassis. Quite often that was > handled by separate ground plains between system and the Ethernet drivers. If > you look at a system that has external magnetic you cans see the split between > the input and output of the magnetics. It was there for noise control as well. > If the SELV is earthed (logic and chassis kinda-sorta the same point) > its functional between that and unearthed SELV, or earthed or unearthed TNV-1, > basic for the rest. Table 2G or figure 2F. > The follow your mains voltage, pollution degrees, and whether or not you going > to see transients and it'll give you the figures your looking for. > Gary > -----Original Message----- > From: Peter L. Tarver [mailto:[email protected]] > Sent: Thursday, February 06, 2003 7:30 AM > To: Alex McNeil; [email protected] > Subject: RE: Ethernet Creepage and Clearance > > > > Ethernet is an SELV signal circuit. Fully IEEE 802.3 > compliant products will not require any special treatment. > Just the usual materials requirements regarding > flammability. > > If this is a powered VOIP product, there may be some > additional things to consider. > > Please be certain to purchase a copy of and read the > standard. > > Regards, > > Peter L. Tarver, PE > Product Safety Manager > Sanmina-SCI Homologation Services > San Jose, CA > [email protected] > > > > -----Original Message----- > > From: Alex McNeil > > Sent: Wednesday, February 05, 2003 11:56 PM > > > > Hi Forum, > > Are there any ethernet and PCB safety > > requirements, ie are there rules like > > those for the modem side of things (isolation in > > particular) or is the > > transformer sufficient? > > > > Kind Regards > > Alex McNeil > > Principal Engineer > > Tel: +44 (0)131 479 8375 > > Fax:+44 (0)131 479 8321 > > email: [email protected] > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
