Brian - The requirement from CSA 22.2 No. 0.4 is now part and parcel of the CSA/UL version of 60950-1. The 40 A current you mention below is based a 20A branch circuit and applies to mains PE. The current value used and the duration of the test are dependent on the circuit size.
For instance, I recently performed this test on a unit with a 60 A mains, so 120 A for 4 minutes were the test conditions for the PE. Another test on the same equipment was at 32 A for 2 minutes, because of a smaller circuit capacity in the area of interest. I don't know the specific reasons Amund was asking about a milliohmeter, so it may not be for this brutish test. Maybe he was interested in a four terminal test for conductive coatings or metal-oxide surface treatments on panels. For folks not interested in paying thousands for the more elegant, self-contained solutions, to performing the Earthing Impedance4 Test from 60950-1, etc., there are simple, though somewhat messy test setups that do very nicely and can cost far less than a kilobuck. Regards, Peter L. Tarver, PE [email protected] > -----Original Message----- > From: [email protected] > [mailto:[email protected]]On > Behalf Of Brian O'Connell > Sent: Friday, March 11, 2005 7:02 AM > To: Amund Westin; EMC-PSTC - Forum > Subject: RE: Milliohm meter > > > Sir > > Even with Kelvin leads, ground continuity > measurements, even using a really nice digital > multimeter, may not be appropriate if you are > testing for compliance to an IEC60950-based > standard. Also, milliohm-ranged measurements tend > to be susceptible to each individual's technique. > > Note that CSA's version of this test requires > that you dump mucho mondo current (typically > around 30A to 40A) through the path for 120 seconds. > > The "true way" to qualify a protective earthing > path is to measure the voltage drop across the > current injection points and calculate the resistance. > > (Do you smell that? Melting insulation, son. > Nothing else in the world smells like that. I > love the smell of mellting PVC insulation in the > morning...) > > luck, > Brian > > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]]On > Behalf Of Amund Westin > > Sent: Thursday, March 10, 2005 11:15 PM > > To: EMC-PSTC - Forum > > Subject: Milliohm meter > > > > > > We are going to measure grounding / bonding > staps, which > > shall not exceed > > 2.5 milliohm. > > Any recommandation for a well good milliohm meter? > > > > Best regards > > Amund Westin, Oslo, NORWAY > > -------------------------------------------------- > -------------- > 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/listserv/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: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ____________________________________________________________ _________________ Scanned by Sanmina-SCI eShield ____________________________________________________________ _________________ 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/listserv/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: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
