James, If your concerns are above 60 Hz, i.e., you’re thinking about HF bonding as well as LF bonding for safety, then I have two excellent resources for you:
[1] T. Williams, K. Armstrong, EMC for Systems and Installations, 1st Ed. Oxford: Newnes. 2000. ISBN 0 7506 4167 3 [2] E.B. Joffe, K. Lock, Grounds for Grounding, 1st ed. Hoboken: Wiley & Sons. 2010. ISBN 978-0471-66008-8 Both books are very good. In [1], have a look at p.121-122. In [2], have a look at p.335-336. Actually, Chapter 5 on bonding, starting at p. 323, is excellent. I could recommend others, but I think those two are a great start. Doug Nix [email protected] +1 (519) 729-5704 > On 15-Feb-22, at 14:48, Douglas E Powell <[email protected]> wrote: > > James, > > Most safety standards have requirements for ground bond testing based on the > current available in the hazard. I've never seen requirements specifying the > type of washer other than it cannot have compressible material in the stack > up, as polymers or fiber washers. > > Back in the day, I learned my earthing (EU) or grounding (US) for high power > equipment from a German expert at LGA Landesgewerbeanstalt Bayern in Nürnberg > and the guidance I received was to use star washers on plain metal surfaces; > not to cut through paint as many believe, but to dig into the metal parts to > provide an oxygen free connection. Yes, initial conductivity for a steel star > washer is not great, but the EU Liability Directive would indicate that the > connection needs to be reliable for up to 10 years. For a normally very low > current (mA) ground to launch into service at a moment's notice, and safely > carry away a few hundred amps, is sometimes a challenge if the long term > environment is in the least bit corrosive. > > Notably, my mentor also allowed serrated lock washers. > > Best, Doug > > Douglas E Powell > Laporte, Colorado USA > LinkedIn <https://www.linkedin.com/in/coloradocomplianceguy/> > > (UTC -07:00) Mountain Time (US-MST) > > > > On Tue, Feb 15, 2022 at 8:34 AM James Pawson (U3C) > <[email protected] <mailto:[email protected]>> wrote: > Hello all, > > > > I’ve given myself a regular internet headache trying to understand the > relative merits of spring vs star washers for use on an earth stud for > protective earthing purposes. > > > > What is the conventional wisdom and justification? I know I can trust you > folks to be above a simple “we’ve always done it this way” > > > > Can anyone point me towards any citable references or standards covering this > subject? > > > > I promise I will write a blog post to pull the information together for > future confused generations. > > > > Thanks and all the best, > > James > > > > > > James Pawson > > The EMC Problem Solver > > > > Unit 3 Compliance Ltd > > EMC : Environmental & Vibration : Electrical Safety : CE & UKCA : Consultancy > > > > www.unit3compliance.co.uk <http://www.unit3compliance.co.uk/> | > [email protected] <mailto:[email protected]> > +44(0)1274 911747 | +44(0)7811 139957 > > 2 Wellington Business Park, New Lane, Bradford, BD4 8AL > > Registered in England and Wales # 10574298 > > > > > > > > > > <https://www.avg.com/internet-security> > This email has been checked for viruses by AVG antivirus software. > www.avg.com <https://www.avg.com/internet-security> > <x-msg://14/#m_848691752694288160_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>- > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. 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To post a message to the list, send your e-mail to > <[email protected] <mailto:[email protected]>> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > <http://www.ieee-pses.org/emc-pstc.html> > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ > <http://product-compliance.oc.ieee.org/> can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ <http://www.ieee-pses.org/> > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > <http://www.ieee-pses.org/listrules.html> > For help, send mail to the list administrators: > Scott Douglas <[email protected] <mailto:[email protected]>> > Mike Cantwell <[email protected] <mailto:[email protected]>> > > For policy questions, send mail to: > Jim Bacher <[email protected] <mailto:[email protected]>> > David Heald <[email protected] <mailto:[email protected]>> > - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
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