Regards, Gert Gremmen Ing.
== Ce-test, Qualified testing == Consultants in EMC, Electrical safety and Telecommunication Compliance tests for European standards and ce-marking Member of NEC/IEC voting committee for EMC. Our Web presence: http://www.cetest.nl List of current harmonized standards http://www.cetest.nl/emc-harm.htm 15 great tips for the EMC-designer http://www.cetest.nl/features01.htm -----Original Message----- From: Ing. Gert Gremmen [mailto:cet...@cetest.nl] Sent: maandag 15 maart 1999 19:35 To: Peter Merguerian Subject: RE: Earth Bonding Requirements for Telecom Equipment Importance: High Hello Peter, I am not familiar with your bullet type wire termination, at least not under that name, so i cannot share my experience with these. About the termination of earth wires; no i know that it's no good practice and it is therefore not allowed in 950. You better bond the two together on a separate bonding terminal and then lead one wire to your 5-pole connector. Even better for reliability is two 3-pole connectors. The main problem with 2 wires in one (crimp) type of connector is that if one of the 2 supply wires is pulled away by brute force, that the other wire goes with it, or if it's not, its connection quality is reduced below acceptable. This certainly reduces the quality of your design, where you used a second redundant supply cable for reliability reasons, you invalid it's redundancy by connecting the two together. I certainly disagree using a shield for safety. One might conclude that shielding is superfluous and replace by unshielded, thereby invalidating the safety concept. Only one solution is acceptable : the right one ;<). In general: safety measures should be visible, and clearly distinguishable from functional circuits, and should never be hidden as a functional circuit. visible : for inspection in manufacturing and quality control clearly as such : so no one in the field might be tempted to replace a unclear measure by a less reliable "equivalent" Regards, Gert Gremmen Ing. == Ce-test, Qualified testing == Consultants in EMC, Electrical safety and Telecommunication Compliance tests for European standards and ce-marking Member of NEC/IEC voting committee for EMC. Our Web presence: http://www.cetest.nl List of current harmonized standards http://www.cetest.nl/emc-harm.htm 15 great tips for the EMC-designer http://www.cetest.nl/features01.htm -----Original Message----- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Peter Merguerian Sent: zondag 14 maart 1999 21:57 To: 'EMC-PST'; t...@world.std.com Subject: Earth Bonding Requirements for Telecom Equipment Dear All, A telecom rack subsystem has two power entry modules (for redundancy); two cables, one for each power entry module, each consisting of 3 leads (+, - and earth), are terminated by means of a 3-pole connector to each power entry module; the other end of the cables are terminated to one 5-pole connector where two of the earthing leads are terminated together in one terminal of the connector and the other four leads (supply) are terminated to each of the remaining terminals of the connector. This 5-pole connnector is the connection to the power distribution unit which has the main earthing terminal, power supply connections and circuit breakers. 1. Do you see a problem with UL1950/EN 60950 of terminating two earth bonding leads to one terminal? I should state that the connector is Recognized but most likely evaluated to accept one wire per terminal. 2. Assuming that the combination of connector and two leads in one terminal was submitted for a separate investigation (to one of the connector standards), is there some clause in the standard which will not allow me to use this type of termination? 3. In lieu of 3 leads/cable, can manufacturer use 2 leads/cable and use the shield of the cable as the earth bonding "conductor"? 4. For wire terminations in general, I find that more and more manufacturers like (for manufacturing reasons) to terminate their leads to insulated bullet type pressure terminal connectors prior to terminating them to connectors and/or terminal blocks employing pressure wire terminals. However, even though the connectors/terminal blocks are Recognized, these bullet type connectors are not Approved. Is anyone using the same technique in manufacturing? If so, do you use Listed and/or Recognized bullet-type pressure wire connectors? If so, can you supply with some manufacturer's names of such connectors? Thanks in Advance, PETER S. MERGUERIAN MANAGING DIRECTOR PRODUCT TESTING DIVISION I.T.L. (PRODUCT TESTING) LTD. HACHAROSHET 26, P.O.B. 211 OR YEHUDA 60251, ISRAEL TEL: 972-3-5339022 FAX: 972-3-5339019 E-MAIL: pe...@itl.co.il Visit our Website: http://www.itl.co.il --------- This message is coming from the emc-pstc discussion list. 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