Hi Tania, Of course..... I have the following to share (below), some of this has appeared on this forum in the past. If any forum members have more to add, please do so.
My opinion and not that of my employer. Regards, Kaz Gawrzyjal [email protected] -----Original Message----- From: Tania Grant [mailto:[email protected]] Sent: Friday, May 25, 2001 1:21 PM To: [email protected]; [email protected] Subject: Re: Double Crimp - History Request Dear Kaz, Surely you are not the only one who would love to know this history. Is it possible for you to share it with the rest of us! Thank you, Tania Grant [email protected] **************************************************************************** * Double Crimp is very elusive to track down. I've had to do this more blankety blank times, and can never find the reference when I want it.... UL, CSA, or TUV will frequently put an explicit reference to double-crimp connectors in their Section General, or in the "engineering" section of their technical files. That is "technical files" in a general sense, thank you. NOT necessarily a TCF or other formal EU document. Basically, you need to put two and two together. The regulations (almost every standard, almost every agency) generally state that certain safety-critical connections require "two independant means of protection." That is the trick phrase. In the case of insulation, of course, we are talking about double or reinforced insulation. In terms of connectors, this "two independant means" translates to: a) For soldered connections, wires must be looped through the terminal strip before soldering. b) For crimped connections, the insulation must be retained independantly of the conductor. To test, they tell you to pretend that one of the two means of retention has failed (i.e. the solder has melted or the conductor has broken). If the result could cause a hazard, then it fails. That's the story. Good luck finding specific references. Mike Mertinooke ********************************************************************** FW: Double RetentionFrom: Dick Grobner [[email protected]] Sent: Wednesday, September 20, 2000 1:01 PM To: IEEE EMC-PSTC E-Mail Forum (E-mail) Subject: FW: Double Retention My 2 cents - I have used a piece of heatshirnk with the inner adhesive (that melts upon shrinking) to comply with the same requirement. The shrink goes over the barrel of the contact / lug and the insulation of the wire. After shrinking / cooling the adhesive retains the wire pretty will. -----Original Message----- From: Gary McInturff [mailto:[email protected]] Sent: Wednesday, September 20, 2000 9:40 AM To: 'Rich Nute'; [email protected] Cc: [email protected] Subject: RE: Double Retention Just adding to what Rich has said below about methods. The double crimp (or insulation crimp) is probably the best method because both crimps are made with the same tool at the same time so there is no manufacturing cost penalty, and several vendors supply the parts and I don't believe that there is any appreciable cost penalty for the parts. Simpler solutions are available if needed. You can tie one wire to the next with a wire tie for example. The first attachment point is the wire to connector pin, the second retention method then is the wire tie which is anchoring the wire itself to an adjacent pin, standoff or whatever. I prefer the first method for several reasons but wanted to point out the next most common, in my experience, method. Gary -----Original Message----- From: Rich Nute [mailto:[email protected]] Sent: Tuesday, September 19, 2000 4:08 PM To: [email protected] Cc: [email protected] Subject: Re: Double Retention Hi Andy: > I have been told that either "double crimp" terminals (fast-ons, ring, > spade) must be used for insulated wire, or a secondary method must be used > to secure the wire's insulation near the point of connection. I have not > seen this described in the standards I have read or in the archived emails > on the RCIC database - where should I look? At this point, I don't even > know if this is a UL or a LVD thing. This is a long-standing, traditional, and semi-secret safety requirement. In my experience, it has been applied by both CSA and UL. The requirement is based on the concept that safety must be provided both for normal conditions and in the event of a fault. Where a wire could come loose and bridge a safety insulation, then that wire must have a second mechanical scheme that prevents the wire from bridging the insulation. The requirement is stated in IEC 60950 and its clones in Sub-clause 3.3.4 for power supply cord wires. This same requirement MAY be applied to other wires at hazardous voltage by the many different certification engineers, each of whom has a different reason for doing so. There is a similar requirement for containment of strands of stranded wire. See Sub-clause 3.3.9. You didn't ask what are the secondary methods. Any secondary method that keeps the wire from bridging a safety insulation is generally acceptable. The "double crimp" is acceptable because the first crimp is to the wire, and the second crimp is to the insulation. Two, more-or-less independent fixings. Best regards, Rich ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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