Hi Rich,
Interesting P.S. comment. Surely this can only be so if one is not dealing with a CE country. I don't see how a test agency can waive the requirements for meeting the LVD in Europe. If it is indeed as you say, then where does it put those of us who have in house safety testing and self certify. Best Regards, Kevin Harris Manager, Approval Services Digital Security Controls 1645 Flint Road Downsview, Ontario CANADA M3J 2J6 Tel +1 416 665 8460 Ext. 2378 Fax +1 416 665 7753 email [email protected] > -----Original Message----- > From: Rich Nute [SMTP:[email protected]] > Sent: Wednesday, August 25, 1999 4:37 PM > To: [email protected] > Cc: [email protected]; [email protected] > Subject: Re: Grounding Bond Test > > > > > Hi Carmen: > > > You ask how to resolve the difference between two, > different production-line (routine) test standards. > > If your product is certified by CSA, then you test > to the 30-ampere value. > > If your product is certified by a CB Certificate > and Test Report, and the issuing body invokes > EN 50116, then you test to the 25-ampere value. > > If your product is certified by UL, then you test > to any current of your choosing. > > So, the answer to your question is: > > Whatever your certification house says. > > In essence, the requirement is proprietary to the > certification house. The certification house can > invoke any production-line test it feels is > necessary. CSA uses 30 amps, 2 minutes. A > certification house that invokes EN 50116 uses > 25 amps, 1 minute as a maximum test. UL does not > require a high-current test. > > The CSA 30-amp requirement derives from the fact > that a CSA circuit-breaker rated 15 amperes (the > most common 120-volt circuit in Canada) is not > required to trip before 2 minutes at a current of > twice rating, 30 amperes. So, the equipment > grounding circuit must withstand 30-amperes for > 2 minutes. > > The CENELEC 25-ampere requirement history is not > at all clear. It has been in both European standards > and UL standards as a type test for many, many years. > It only appeared as a routine test when EN 50115 was > published a few years ago. > > By the way, neither high-current test (as a > production-line test) will identify continuity > problems any better than a low-current test. > > The presumption is that the high-current test will > identify a manufacturing defect in the grounding > circuit, while a low-current test will not. > > In actuality, the grounding circuit, in order to pass > the type test, had to be properly designed to handle > the high current, no matter whether 25 amps or 30 > amps. So, for the production-line, we need to be > assured, by test, that the high-current circuit has > been assembled correctly and with no defects. > > The high-current test WILL NOT identify loose screws > if the conductors are making contact! The high- > current test WILL NOT identify cut strands of wire > if there are 3 or more strands in the circuit! > (Feel free to duplicate these tests or any other > grounding circuit defects you can imagine; the > circuit will pass the high-current test!) > > The high-current test does not identify continuity > problems any better than a low-current test. > > I did point this out to the EN 50116 committee when > they asked for comments before it was published. > Interesting that the committee ignored the data and > required the test anyway! I guess the lesson is: > don't confuse a technical committee with technical > facts. > > > Rich > > > ------------------------------------------------------------- > Richard Nute Product Safety Engineer > Hewlett-Packard Company Product Regulations Group > AiO Division Tel : +1 858 655 3329 > 16399 West Bernardo Drive FAX : +1 858 655 4979 > San Diego, California 92127 e-mail: [email protected] > ------------------------------------------------------------- > > > > ps: In high-volume production, both the 1-minute > and the 2-minute tests are unacceptable to the > manufacturer. It seems that most certification > houses will waive the long-term test in these > cases! This seems to admit that the high-current > test is not particularly valuable. > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
