It is definitely not a requirement for EMC, regardless of the standard. The ground connection has no function in EMC but for the extremely low frequencies.
I believe that is a generic design principle to ALWAYS connect protective ground first and disconnect last when connecting any connector regardless the requirements of the standard. Even when using fixed connections make a habit of placing the ground connector in such a place that when pulling of the wires by force, the ground wire is pulled out last. (many connectors for fixed wiring do have such a topology by default) If that is impossible, wiring practice normally prescribe that the ground wire be cut off slightly (0.5") longer then phase and return wires of the cable, ensuring the proper disconnect order of the wires even if forced. A peoduct safety designer should not inquire if any design rule is mandatory in a specific standard, but instead, question himself if any extra safety measure can be included in the design without exceeding the design specifications (might include cost!). The PE connect first disconnect last principle is so fundamental to safety, that it should be honored in any design, even not mains related. The ground connection is one of the 2 fundamental safety layers between user/operator and parts at live voltage. As important as insulation. Would you ask the same question if it concerned internal wire insulation ? The actual moment of connecting/disconnecting power plugs is precisely the same moment where users put one hand on the equipments cover and push-in/pull-out the plug with the other hand. At that same moment emc filter capacitors charge with a high peak current steered by a possible steep voltage (up to 320 Volts in europe). Equipment needs grounding most at exactly *that* moment. Regards Gert Gremmen ce-test -----Original Message----- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Lou Aiken Sent: maandag 1 juli 2002 17:27 To: Jon Jones; Emc-Pstc (E-mail) Subject: Re: EN60950 functional earthing. My recollection is (without reading the standard) that the make first / break last requirement only applies to connectors operated by the user or other non trained persons. Then it should also seem reasonable that the requirement would not apply to a product meeting ALL class II requirements. However, protection preventing contact (by the test finger) with a live pin of a partially inserted plug or connector WILL apply if the connector can be used by non trained persons, regardless of the protection class.Rgds, Lou Aiken, LaMer LLC 27109 Palmetto Drive Orange Beach, AL 36561 USA Tel 251 981 6786 Fax 251 981 3054 Mobile 251 979 4648 ----- Original Message ----- From: Jon Jones <jon.jo...@atltelecom.com> To: Emc-Pstc (E-mail) <emc-p...@majordomo.ieee.org> Sent: Monday, July 01, 2002 11:40 AM Subject: EN60950 functional earthing. > > Group, > > Regarding Functional earthing requirements for Class II equipment. > > Is there a general requirement for the functional earth in an equipments > power connector to follow the make first break last rule with regards to EMC > (EN55022) and Safety. > > Thanks in advance > > > Jon Jones > ATL telecom. > > > ------------------------------------------- > 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: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://ieeepstc.mindcruiser.com/ > Click on "browse" and then "emc-pstc mailing list" > ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
