Rich Nute has 3 Technically Speaking columns on this that can be found at the In Compliance magazine website. The first is here https://incompliancemag.com/article/derivation-of-ground-impedance/ and I find it quite informative. Mike Sherman Graco Inc.
> On 05/12/2021 8:01 AM Wiseman, Joshua > <joshua.wise...@orthoclinicaldiagnostics.com> wrote: > > > > I agree with Brian. I’ve been involved with product safety over 20 yrs > and worked for an NRTL for about 6 of those. > > > > The 40 A requirement came from the Canadian electrical code and all the > NRTLs. > > > > The only exemptions I’ve seen to the 100 % ground bond requirement has > been for Class II and Class III devices or devices using an external power > supply (brick or wall-wart styles.) > > > > Josh > > > > From: Brian Kunde <bkundew...@gmail.com> > Sent: Wednesday, May 12, 2021 8:42 AM > To: EMC-PSTC@LISTSERV.IEEE.ORG > Subject: Re: [PSES] Ground Bond Tests > > > > EXTERNAL SENDER: Verify links, attachments and sender before taking action > > > > 61010-1 § 4.1 says, "Tests in this standard are TYPE TESTS to be carried > out on samples of equipment or parts. Their only purpose is to check that the > design and construction ensure conformity with this standard. In addition, > manufacturers shall perform the ROUTINE TESTS of Annex F on 100 % of > equipment produced which has both HAZARDOUS LIVE parts and ACCESSIBLE > conductive parts." > > > > 61010-1 Annex F, § F2 calls out the "Protective earth" test, also known > as the Ground Bond Test, as a required test to be performed on 100% of > production. Note the "NOTE" that says, "No value is specified for the test > current.". So some NRTL inspectors allow the ground bond test in production > to be performed at any reasonable current value, but most will follow the > requirements of 6.5.2. > > > > > > I have been doing Product Safety for over 30 years and have worked with > UL, CSA, TUV, NEMKO, EOLAS, etc., and all of them require 100% testing of > production units to both the Highpot test and the Ground Bond test. > > > > Regarding the 100mΩ verses 200mΩ question, all the NRTL inspectors I have > worked with require the measured impedance of the Power Cord to be no more > than 100mΩ. Note the UL/ANSI/CSA Deviation to 6.5.2.4 that instead of the > 100mΩ requirement has a "shall not cause a potential drop of more than 4 V". > At a minimum 40 A ground bond test, a 100mΩ impedance would give you a 4V > drop. It doesn't say anything about an 8V drop for non-detachable power > cords. So NRTLs are going to stick with the 100mΩ across the board, I > believe (this is opinion). > > > > Hope this information is helpful. > > > > The Other Brian > > > > > > On Tue, May 11, 2021 at 11:27 PM Steve Brody <sgbr...@comcast.net > mailto:sgbr...@comcast.net > wrote: > > > > > > So here is my question, or actually two of them: > > > > > > > > First, one of my clients has been told by their 3rd party NRTL that > > a ground bond test is required as part of factory/production routine tests, > > even though it is not required by 61010-1. I have never run into this > > requirement in my work history and I would be interested in hearing if any > > of you have. > > > > > > > > Second, just to be sure my interpretation is correct, 61010-1, > > section 6.5.2.4, Impedance of protective bonding of plug-connected > > equipment, in the fist sentence, it has a limit of 100 mOhms impedance and > > my read is that this is for equipment with a power cord that has a plug on > > one end and a receptacle on the other. > > > > > > > > Then, in the same section, still under the title of plug-connected > > equipment, it says for equipment that has a non-detachable power cord the > > limit is 200 mOhms. My interpretation is that plug-connected equipment > > with a non-detachable power cord is when the power cord is hard wired to > > the unit under test, but still has a plug for mains connection. > > > > > > > > Thoughts? > > > > > > > > Thanks in advance and you can reply here or privately to > > stev...@productehsconsulting.com mailto:stev...@productehsconsulting.com > > > > > > > > > > > > Steve Brody > > > > sgbr...@comcast.net mailto:sgbr...@comcast.net > > > > C - 603 617 9116 > > > > - > > ---------------------------------------------------------------- > > > > 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 <emc-p...@ieee.org> 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 <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
