The following is a guess on my part. Most household breakers (USA) are 15 Amps for power wires that appliances can plug into. If a fault occurs, over the time until the breaker pops, the time averaged current will be somewhat in excess of 15 Amps. That means that the time-averaged hazard potential with a 0.1 Ohm bond will be just over 1.5 Volts, which is not a hazard, even in a wet area. I expect that using 25 Amps to test the bond makes sure the bond path has the ampacity not to fuse open before the circuit protection device.
---------- >From: ron_well...@agilent.com >To: emc-p...@majordomo.ieee.org >Subject: Bonding Impedance >Date: Wed, Jul 24, 2002, 3:57 PM > > > Hello all, > > I recent issue has come up for me regarding why some safety standards > specify 100 milliohms as the acceptable impedance for a protective earth > ground bonding test. I am curious as to what the rationale is for this > specific value and why 25 amps is chosen as the default test current. > > Regards, > +=================================================================+ > |Ronald R. Wellman |Voice : 408-345-8229 | > |Agilent Technologies |FAX : 408-553-2412 | > |5301 Stevens Creek Blvd., |E-Mail: ron_well...@agilent.com| > |Mailstop 54L-BB |WWW : http://www.agilent.com | > |Santa Clara, California 95052 USA| | > +=================================================================+ > > ------------------------------------------- > 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" > ------------------------------------------- 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"
