Dear Paolo , In 60601-1 2nd edition, philosophy was that currents intended to produce physiological effect are functional currents, as oppose to leakage currents which are unintentional (see Appendix 2.5.4). Leakage current requirements will apply to the unintentional patient currents. Functional patient currents would be tested against design specifications. I don't think that the presence of a functional current obviates the need to restrict leakage currents, which might be very different in nature (eg: HF electrosurgical functional current v. power-frequency leakage currents). I think your quote from the 3rd edition is consistent with the principles of the 2nd edition - my interpretation would be that nothing has changed in this respect.
Regards, Ged Dean Nottingham University Hospitals NHS Trust From: [email protected] [mailto:[email protected]] On Behalf Of Paolo Peruzzi Sent: 12 June 2007 10:52 To: [email protected] Subject: patient leakage current limits exemption Dear group, As concerns leakage current limits, IEC 60601-1 third edition states at paragraph 8.4.1: "The limits specified in 8.4.2 do not apply to currents that are intended to flow through the body of the patient to produce a physiological effect during normal use" One could argue that this clause is not a new one, since the (very useful) mapping document between the second edition and the third edition, links it to the point 16.a.1) of the second edition. But I think they are different requirements, since 16.a.1 in the 2dn edition doesn't say anything about exclusion from leakage current limits. Does it means that any medical system which delivers intentionally a current through the patient body is exempted from patient leakage current limits only in the newest standard, and it is not according to the old one? Thanks in advance, Paolo Peruzzi Regulatory Medical R&D El.En. S.p.A. Via Baldanzese, 17 50041 Calenzano (FI) Italy Tel. +39 055 8826807 FAX +39 055 8832884 http://www.elengroup.com/ - 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/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 This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by Mailmarshal for the presence of known computer viruses. Please note from the 1st of April all hospital email addresses will be in the format of [email protected] Nottingham University Hospitals NHS Trust Queens Medical Centre Campus ICT Services ID:QMCICT1 - B466ebe110000.000000000001.0001.mml - Sophos Anti-Virus 16:38:57 06/12/07 - 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/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 ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
