In addition to bloody fingertips, you might want to consider the possibility of these broken off finger stock landing on circuits and shorting something, that might, in turn, cause a hazard. Contemplating the variety of abnormal test requirements for such a
possibility is enough for me to pressure our engineering to seek other solutions! Tania Grant, Lucent Technologies, Octel Messaging Division tgr...@lucent.com ______________________________ Reply Separator _________________________________ Subject: Re: FW: EMI gaskets Author: "ron_pick...@hypercom.com" [SMTP:ron_pick...@hypercom.com] at CORP List-Post: emc-pstc@listserv.ieee.org Date: 3/18/98 10:27 AM Brian, You have cited the only reference that might construe concern of these fingers, however, I do not know what you mean by "if correctly designed-in". You also did not elaborate on the performance difference between the 2 gasket materials. Please note that the 2nd paragragh of 1.3.1 of UL 1950 states "Where the equipment involves technologies and materials or methods of construction not specifically covered, the equipment shall provide a level of safety not less than that generally afforded by this standard and the Principles of Safety contained herein." This might be indicating that, in the context of 4.1.4, the delineation between OPERATOR and SERVICE PERSONNEL may not be as black & white as you have depicted, but a bit muddied. Granted, it is expected that service people are better trained technically than operators. Also granted that service people know of this type of risk and can work around it. But because of that, don't expose them to a known and possibly hidden risk. I'm sure that they wouldn't appreciate it. Some experience that I've had in a past life with finger gaskets of this type has been that they are easliy damaged through handling and then become more of a hazard with broken finger stubs producing sheared edges. Bear in mind that there are indeed alternatives to adequate shielding of this type, with the foam being only one. Also, what is the difficulty for not wanting to provide to the customer what he wants? So much for my opinionated 2 cents worth. Regards, Ron Pickard rpick...@hypercom.com ______________________________ Reply Separator _________________________________ Subject: FW: EMI gaskets Author: <f...@netc.ie> at INTERNET List-Post: emc-pstc@listserv.ieee.org Date: 3/18/98 12:29 PM - Subject: EMI gaskets I am interested in hearing the experiences of anybody out there who has had a need for using EMI gaskets, in particular between metal faceplates of circuit packs in a Telecomms Sub-rack. We have evaluated BeCu finger stock and foam covered with a metallised fabric and have found the metal fingers out-performed the foam. But, due to customer complaints relating to safety hazards posed by the metal fingers we are being pressured to use the foam. Has anybody else faced similar problems ? >From our experience, if the fingers are designed suitably for the application and applied correctly there should not be a hazard. My reading of IEC950/EN60950/UL1950 does not indicate any prohibitive clause relating to metal fingers. The closest (4.1.4) only stipulates protection of the OPERATOR and does not refer to SERVICE PERSONNEL, who would be the only persons exposed to the risk i.e. it is only when a module is withdrawn from a shelf that the fingers are exposed (our equipment is Central Office type). Does anybody know of any safety/regulatory objective reasoning for not using fingers, if correctly designed-in, in an application such as ours ? Regards, Brian McAuliffe Regulatory Engineering Tellabs Ltd Tel: +353.61.703269 --openmail-part-000dead1-00000001 --openmail-part-000dead1-00000001--