John - That impedance value is suprisingly high, but tends to support the contention that the fault current at an outlet will be much lower than was suggested (65kA, which, to me, appeared more like a peak surge current than a fault current).
For those interested, below are what the IEC Web Store has to say about IEC 60725. Title: Considerations on reference impedances for use in determining the disturbance characteristics of household appliances and similar electrical equipment Abstract: Records the information that was available and the factors that were taken into account in arriving at the reference impedance of 0.4+ j 0.25 ohm which has been incorporated in IEC 60555. Has the status of a technical report. 0.5 Ohm seems large for a flexible cord. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA [email protected] > -----Original Message----- > From: John Woodgate > Sent: Wednesday, January 29, 2003 2:10 PM > > > H'mm. IEC 60725 gives a 'reference impedance' (a > sort of weighted > average, omitting extreme values) for a 230 V 50 > Hz 100 A service-rating > household supply as 0.47 ohms at the service > entry. Allowing another > 0.5 ohms for the mains wiring and the flexible > mains lead, we get 230 V > and 0.97 ohms at the appliance, giving a > prospective short-circuit > current of about 240 A. 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
