Doug and Bev and all in Techieland I shall try to keep the commercial out of this but it ain't easy so please don't flame me. In order to run SIR we recommend the use of a "calibration coupon" upon which is mounted "known-value" resistors: 1E06, 1E08, 1E10 and 1E12. The calibration coupon is fitted into a Faraday Cage. We send the "calibration coupon" to a NAMAS accredited test house who then produce for us a "Calibration Certificate" that details the values recorded, the voltage applied and the "uncertainty of measurement" or tolerance. Prior to any SIR test, we recommend that the "Calibration Coupon" is mounted into the test rack (if used) and then the SIR system takes a reading from the coupon that should, or in our case would, be within the desired range. The desired range should be something similar to IEC 61189-5 that details: Up to 1E10 ±5% 1E10 to 1E11 ±10% Above 1E11 ±20% The only oversight in this International Standard is that they do not state the test voltage which, as Brian stated, is rather important. As I am presently charged with re-writing the next update of IEC 61189-5, I am taking myself into a corner and giving myself a good talking-to! I hope this helps -- Regards Graham Naisbitt [log in to unmask] Golf quote of the week: I don't trust doctors. They are like golfers. Every one has a different answer to your problem. CONCOAT - Engineering Reliability in Electronics CONCOAT SYSTEMS - Measuring Reliability in Electronics A British Manufacturer www.concoat.co.uk & www.concoatsystems.com Cell: 079 6858 2121 Office: +44 (0)1252 813706 --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------