Ahh Ken, Come on now, its not broken, only a flesh wound ;-)
We do have a problem with folks piddling around in none value added detail, which is why I'm being so belligerent about this. Just for good measure, we disagree over Denis being correct too :-) Cheers, Derek. On 10/11/2011 1:29 PM, Ken Javor wrote: Within his frame of reference, Ward is correct, which is why this entire accreditation process is flawed and broken. We got along without it before, and it is adding nothing but extra costs and bureaucracy, and negative value to the process of controlling EMI. Ken Javor Phone: (256) 650-5261 ________________________________ From: Dennis Ward <dw...@acbcert.com> <mailto:dw...@acbcert.com> Reply-To: <dw...@acbcert.com> <mailto:dw...@acbcert.com> Date: Tue, 11 Oct 2011 11:15:00 -0700 To: 'Derek Walton' <lfresea...@aol.com> <mailto:lfresea...@aol.com> Cc: 'Grace Lin' <graceli...@gmail.com> <mailto:graceli...@gmail.com> , 'WNya' <wendy...@yahoo.com> <mailto:wendy...@yahoo.com> , 'EMC-PSTC' <EMC-PSTC@LISTSERV.IEEE.ORG> <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: RE: Table Size in Emissions test HI Derek The point of anything ‘nominal’ is that it starts with what is expected and allows reasonable variations of sorts. And you hit the right words “relating to a designated or theoretical size”. If you say you must follow the standard, then follow it. The designated size of a table is 1m x 1.5m x 0.8m. This then is the size generally expected. It is not a micrometer reading with 0.01m measurement uncertainty tolerances; it is a general designated and expected size – a nominal size. Now, and without going into uncertainties and its minutia, a 0.8m x 1.2m table, while not typically or generally expected, could be stretched to be within a range of what could be considered within the nominal range. Likewise a table 1.2m x 1.8m would or should still be considered within an expected or nominal value. To the contrary, a table 0.2m x 0.2m, for many reasons, would not be generally considered expected and thus not nominal, but abnormal in size for the intent and purposes of the standard. Remembering that there are three dimensions given (i.e. 1mx1.5mx0.8m), if we take your ‘exception’, then I could place a device on the ground plane as long as it was on a nonconducting surface. Yet I know of no lab nor auditor that would accept this as a ‘nominal’ height condition for any of the standards mentioned. I would not be able to reject or challenge their claim that my table height was not 80cm by saying, nominal is “of, being, or relating to a designated or theoretical size that may vary from the actual, and I don’t have to have a table 80cm high.” One might say, yes, but height matters. And they would be correct, however, the dimensions are together in the same frame of reference in the same sentence. So any exceptions to the dimensions would have to follow the same process. The issue then is not uncertainty and its issues, but what is generally expected and accepted as a reasonable table for the intent of the standard. Remembering that standards are produced as much to make something consistent wherever used, then the nominal would be that which is generally consistent within the population that uses the standard. As to ‘bigger fish to fry’, this would be a good size fish for a lab that was seeking accreditation. Yes there are allowable variations, equipment considerations, etc that can be discussed with the accrediting organization. To say that because ‘nominal’ is used and because ‘shall’ is not, I can do what I want, is simply not the case if they want to become accredited. It is fairly easy and cheap to construct a nominal table of dimensions in the standards. There is probably more money, time and effort in trying to challenge or reject the assessment than to simply hire a carpenter and build one. But the choice is the labs and how they wish to relate to their accreditation body. Dennis Ward Director of Engineering American Certification Body Certification Resource for the Wireless Industry http://www.acbcert.com 703-847-4700 fax 703-847-6888 direct - 703-880-4841 From: Derek Walton [mailto:lfresea...@aol.com] Sent: Tuesday, October 11, 2011 10:09 AM To: Dennis Ward Cc: 'Grace Lin'; 'WNya'; 'EMC-PSTC' Subject: Re: Table Size in Emissions test Sorry Dennis, you are not correct. Nominal means: b : of, being, or relating to a designated or theoretical size that may vary >from the actual. This is from Websters. As you indicate, there is NOTHING that says it has to be 1 by 1.5m I'm sorry to be so anal about this, but it is happening too much where assessors are assessing to opinions and personal agendas. We must follow the standard. Usually there are MUCH bigger fish to fry than quibbling over something like this I repeat, again, that there is NOTHING that says the table SHALL be 1 by 1.5m. Only then could a deficiency be written. Sincerely, Derek. On 10/11/2011 11:43 AM, Dennis Ward wrote: Both ANSI C63.10 and ANSI C63.4, the typical standards for which ISO17025 accreditation is used, contain the following statement, “Tabletop devices shall be placed on a nonconducting platform, of nominal size 1 m by 1.5 m, raised 80 cm above the reference ground plane. While a bit more open to variation due to size of equipment, CISPR 22 has the statement “Equipment intended for tabletop use shall be placed on a non-conductive table. The size of the table will nominally be 1,5 m ◊ 1,0 m but may ultimately be dependent on the horizontal dimensions of EUT. So while you may challenge the accreditation organization, they are correct, your table does not meet the ‘nominal’ size requirements for at least the two standards ANSI C63.4 and C6310. Other standards may also have the nominal size issue as well. Thanks Dennis Ward Director of Engineering American Certification Body Certification Resource for the Wireless Industry http://www.acbcert.com 703-847-4700 fax 703-847-6888 direct - 703-880-4841 From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Grace Lin Sent: Tuesday, October 11, 2011 4:16 AM To: WNya Cc: EMC-PSTC Subject: Re: Table Size in Emissions test Wendy, When I look for an accredited ANSI C63.4 laboratory, I expect the laboratory has the facility as stated in the standard, including a standard size of the table as defined in the standard. For this reason, unless the accreditation certificate bears a restriction note, I support the auditor's comment. >From the other point of view, many manufacturers' laboratories are for internal use only, including my employer's. For this reason, the auditor may be willing to accept the smaller size of the table. The question is how to determine if the laboratory is for internal use only (for testing certain type of products). An example is Alcatel-Lucent's EMC laboratory in New Jersey, USA. It opens to the general public. With regards, Grace On Mon, Oct 10, 2011 at 7:54 PM, WNya <wendy...@yahoo.com> <mailto:wendy...@yahoo.com> wrote: Dear Experts, Recently my company went through the first ISO17025 audit. We have a table smaller than the standard requirement of 1.5m x 1m since our products are small, typically 10cm x 10cm x 10cm. The height of our table was 0.8m. The auditor wanted us to change the table size to follow the standard. What does it matter since we never use the extra space on the table? I do agree we must keep to the height requirement since the floor is a ground plane and thus it sets a fixed capacitance to the EUT and also controls the lengths of any attached cables. Can we reject or challenge the auditor's request? Has anyone experience the same situation? 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