<1615323...@snellwilcox.com>, duncan.ho...@snellwilcox.com wrote: >Has anyone ever used a combination of metals not listed in annex J of >EN60950 for a protective earthing connection? If so can anyone suggest a decent >source of information on electrochemical potentials for various materials. > >The particular materials in question are tin plated copper on zinc passivated >steel. Can anyone advise on the electrochemical potential of such a connection?
I did an investigation on this because there was an error in the table in earlier editions of 60950 and TC92 wanted to copy the table and error into 60065. The real corrosion experts say that the Annex J table is useless! These electrochemical potentials are measured under laboratory conditions with no contamination and no ions present except those involved in the measurement. In real life, there is dissolved oxygen, chloride, sulfate and maybe nitrate ions, with carbonate of course. Under those conditions, in some cases corrosion does not occur when the table predicts it, but does occur when the table doesn't predict it. In your case, my GUESS is that you are fairly safe with that combination. You might try searching for textbooks and papers on corrosion testing. I doubt that there is a very well-informed web site, but you never know with the web! The world authority on contact corrosion might be a web enthusiast. -- Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839 Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk I wanted to make a fully-automated nuclear-powered trawler, but it went into spontaneous fishing. ------------------------------------------- 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: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
