Dear Jon, Dick and All Memebers, I believe the UL method for Production-Line Grounding Continuity Test is just to verify that someone did not forget to connect the earthing lead from the appliance inlet or power corrd to the chassis. Therefore an "ohmmeter, buzzer or the like" is all that is considered necessary. The feeding of an ac or dc current between the protective earth terminal and other parts of the unit likely to be energized by a single insulation fault is not necessary during the production-line tests because these tests have already been conducted by the lab during the type tests. UL and other NRTLs want to make sure that assembler did not forget to connect the main earthing lead.
Also, if you check a UL or NRTL descriptive report used for the quarterly folow-up inspections, you will note that the construction of the product has been described in detail, including but not limited to earthing connections, enclosure, covers, screws and washers, etc. European test labs for follow-up purposes, use a "Critical Components List" but do not describe the construction of the product in detail. Hence, they require the feeding on an ac or dc low voltage current source into the earthing path for each production unit. Regards PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 -----Original Message----- From: Jon Griver [mailto:[email protected]] Sent: Tuesday, May 22, 2001 9:06 AM To: Dick Grobner Cc: [email protected] Subject: RE: Production Line Test Requirements - Medical Devices Dick, This is the situation as I understand it. Please note that a few years ago I did factory inspections for TUV Rheinland, so I'm speaking from a position of some knowledge (though a bit outdated). UL includes its production test requirements in its standards. It traditionally has only required a check of earth continuity under low current conditions. The European test labs work on the basis of extracting production tests from the standards. They require these tests to be performed as a condition of using their mark on the product. It is the test lab's decision which production tests are to be performed and it is not mandated by any standard. Traditionally, the European test labs require the earth continuity test to be carried out at high current conditions, as in the standard. The logic behind this is that if there is a fault to earth, it will cause a high current which may cause any weak links in the earth circuit to heat up and possibly char and increase in resistance or even burn out completely. (We've all seen charring around sockets). Thus this test is considered more effective in identifying loose connections, etc. due to production mistakes than the UL test, which might miss them. Presumably if you are selling your medical product in the EU, you have a Notified Body (unless your product is Group 1). You should agree your production test plan with them. Be aware that they may insist on the high current earth continuity test. Good Luck, Jon Griver Medson Ltd > -----Original Message----- > From: Dick Grobner [mailto:[email protected]] > Sent: Monday, May 21, 2001 18:23 > To: 'Jon Griver' > Cc: IEEE EMC-PSTC E-Mail Forum (E-mail) > Subject: RE: Production Line Test Requirements - Medical Devices > > > Jon > Thx for the info, however, I re-checked the two known US > standards (UL2601, > Appendix D - Manufacturer's Responsibilities, Construction Considerations > and Requirements for Factory Tests) (NFPA 99, Grounding Circuit > Continuity - > Measurement of Resistance). UL defines "Production Line Grounding > Continuity > Test Equipment" as: Any suitable continuity indication device (such as an > ohmmeter, a battery and buzzer combination, or the like) may be used to > determine compliance with Grounding Continuity Test requirements. The NFPA > std is even less definitive on this matter. > EN60601-1, Appendix B - "Testing During Manufacture and/or Installation", > Not Used. See rational to sub-clause 4.1. Which states - Tests > described in > this standard are type tests. > > I checked all of the amendments including EN60601-1 for medical > systems, and > I do not see anything changing this. > > My questions remains, where does it state to use the 10-25Amp, 50 > or 60Hz @ > 6Volt for 5 seconds test? Is this a carry over from another EN > standard? Why > wouldn't a simple continuity tests as defined by UL be appropriate from > equipment coming off of the production line (assuring that the protective > earth circuit in intake)? > > Appreciate your feedback Jon! & thanks again. > > Does anyone else on this forum have any input - would appreciate it. > ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall," ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
