Doug, Have you checked out IEC 60601-2-38, Particular Requirements for the Safety of Electrically Operated Hospital Beds. This standard may clarify how you measure earth leakage current and patient leakage current for a hospital bed. (I don't have a copy of this standard, so I'm guessing).
IEC 60601-1, in Table IV note 3, does allow less stringent limits for earth leakage current when the protective earth is permanently connected. However it's not clear to me how to measure patient leakage current for a hospital bed, if at all, and the answer to this is likely to be in IEC 60601-2-38. You say "The measured leakage current from the power supply exceeds the patient leakage requirements (0.1mA)". It's not clear to me exactly from what point you are measuring leakage current, and whether that current is to be considered "patient leakage current", or even whether the leakage current you are measuring is required to be measured by the standard. Best Wishes, Jon Griver http://www.601help.com The Medical Device Developer's Guide to IEC 60601-1 ----- Original Message ----- From: "Doug Beckwith" <[email protected]> To: "EMC-PSTC" <[email protected]> Sent: Tuesday, October 11, 2005 5:32 PM Subject: 60601-1 and patient leakage current > Hi All, > Question time again, this time concerning patient leakage > current and permanently connected Class 1 equipment with a > permanently connected earth. > > I have a product that exceeds the patient leakage current > between the mains and the accessible metal parts of the frame (a > motorised bed). The accessible metal part is pemanently > connected to PE. The measured leakage current from the power > supply exceeds the patient leakage requirements (0.1mA). I > searched 60601-1 and I cannot find any exception that allows for > increased leakge current limits. > If you have a metal part that is connected to earth with a > resistance of <0.1 ohm, the potential on the accessible part > shoul closely approximate 0V. I can understand the leakage > requirement if the part is not earthed, but there should be an > exception if the part is at earth potential. > > Help, I have a feeling I am missing something. All assistance > gratefully received. > > Regards > > Doug > > > > > > > > __________________________________________________________ > Find your next car at http://autos.yahoo.ca > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/listserv/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > > -- > No virus found in this incoming message. > Checked by AVG Anti-Virus. > Version: 7.0.344 / Virus Database: 267.11.14/128 - Release Date: > 10/10/2005 > > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
