In message <web-151977...@california.com>, dated Fri, 10 Aug 2007, Robert A. Macy <m...@california.com> writes:
> For example, maximum leakage in Medical Electronics for direct >connection to patients is around 10uA Yes, because the current may have a low-impedance path to a vital organ, especially the heart. > Maximum leakage for AC mains RFI/EMI filters is 2 mA, and typically >around 1 mA. Yes, because skin is a fairly good insulator as far as biological materials go. > >These limits are based upon potential harm for some time period, and >are specified using easily measurable current. > > >But I need a limit based upon joules. For example, in the winter as we >slide across the car seat, we don't die from the 18 Kv zap. low >capacitance prevents lethal harm. Low current results from the low capacitance. It's current that matters, not energy. > So what 1/2 C V^2 kills people? > >Is there a published limit? >Is there a reference for max allowed? The international source is IEC TR60479-1 Part of the Scope clause reads: For a given current path through the human body, the danger to persons depends mainly on the magnitude and duration of the current flow. However, the time/current zones specified in the following clauses are, in many cases, not directly applicable in practice for designing measures of protection against electrical shock. The necessary criterion is the admissible limit of touch voltage (i.e. the product of the current through the body called touch current and the body impedance) as a function of time. The relationship between current and voltage is not linear because the impedance of the human body varies with the touch voltage, and data on this relationship is therefore required. The different parts of the human body (such as the skin, blood, muscles, other tissues and joints) present to the electric current a certain impedance composed of resistive and capacitive components. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 emc-p...@ieee.org 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 emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com 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 ______________________________________________________________________
