John -
IEC60950-1, §2.6.2 deals with Functional Earthing. If the earthing is functional only, it does need to be separated by Double or Reinforced Insulation, or by earthed screening and Basic Insulation, from parts at hazardous voltage. Just as for Pluggable Equipment/Class I Equipment, when an earth is brought into the equipment in a power supply cord, even if only to facilitate Functional Earthing, the double insulated symbol (IEC60417-1, Symbol 5172) can not be used. §1.2.4.1 defines Class I equipment as relying on both Basic Insulation *and* Protective Earthing. The Note to §1.2.4.1 states that Class I Equipment may also contain Double or Insulation and this appears to be the nod that Rich was referring to. No where does the standard state that by simply providing a Functional Earth, even through an appliance inlet (implying use of a power supply cord), the equipment is not considered Class II. One is simply limited to not marking with the aforementioned symbol. I'd appreciate hearing more from you on this Rich. Regards, Peter L. Tarver, PE ptar...@ieee.org > From: Tyra, John > Sent: Tuesday, November 04, 2003 6:30 AM > > Great answers Rich! > > I do have one question for the group just for my > own knowledge...back in my > TUV days I worked almost exclusively with > IEC60950 and seem to remember that > a class II product can have a functional earth > connection provided Primary > and other hazardous voltages are insulated from > earth by reinforced > insulation. In this scenario even thought the > product has an earth > connection would it still be considered class II > with regards to the > IEC60950 standard and have to be marked as such? > Maybe it is semantics as you reference > "protective earth" so it must be > class I as opposed to functional earth which is > not relied upon for > safety......... > > > Regards, > > John Tyra 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: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
