Joe, I agree with your conclusions and your interpretation is correct in my opinion, however painful the result may be.
Use of the harmonized technical standards is the most prevalent path to LVD compliance in our industry. As such, compliance with all the Normative requirements is an essential first piece. Annex ZB is a normative part of the standard and in my opinion those normative annexes form a required part of the process under the national legislation supporting the LVD. It is not correct that these Normative annexes of the standard are only applicable when getting a National Approval. They are applicable to CE marking and should be applied based on the country you intend to distribute the product as part of compliance with the EN standard. If you look in IEC 950, the requirement for supplementary insulation for a primary circuit for Sweden is in Clause 6.3.3.1, the same requirement (just worded differently) for Norway is in Note 5 of Clause 6.2.1.2 and Note 2 of Clause 6.2.1.4 and the same requirement (again worded differently) for Finland (yes, Finland, just ask FIMKO) is located in Note 1 of Clause 6.2.1.4. I agree that supplementary insulation may be avoided by the use of a Type B plug or a permanent connection. However, how many modem manufacturers know that the end products utilizing their modem will be using a Type B plug or a permanent connection? The biggest problem with these requirements is that so few companies and test houses seem to know anything about them. Guessing from the CB scheme reports seen from many OEMs, there are likely to be tons of modems in Norway, Sweden and Finland that do not comply (of course, we require that the OEM fix them to have supplementary insulation before they bear my employer's name). Companies get their CB report that says they have basic insulation between TNV and SELV and that they comply with the requirements for Norway, Sweden and Finland and they ship product. Even Class 2 equipment can be affected. If one can connect the Class II product to a Class I product (like a printer), you now have a possible connection to ground and supplementary insulation is required between parts that could be earthed and the Telecommunication Network. Let me also mention that this requirement is not limited to TNV-3. Note 2 of Clause 6.3.3.1 specifies that supplementary insulation is required between the telecommunication network and any parts or circuitry that may be earthed. Therefore, as ISDN is considered to be a telecommunication network per Clause 1.2.14.7, it must also use supplementary insulation. Today, the only way to handle this situation if one wants to have a truly worldwide, or "Eurowide", product is to put supplementary insulation between any type of TNV circuit and any potential ground or potentially grounded SELV or to have a special product that can only be used with a Type B plug or permanent connection. The above does not necessarily represent the views of my employer. Thanks, Walter Overcash Product Regulatory Engineer Email: [email protected] <mailto:[email protected]> -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Wednesday, August 19, 1998 11:17 AM To: [email protected] Cc: [email protected] Subject: CE marking vs. Annex ZB in EN60950 I am trying to sort out an an apparent contradiction between the main body of the "harmonized" EN 60950 and the national deviations that appear in Annex ZB. I would appreciate some assistance from the safety professionals and regulatory experts in the emc-pstc and treg forums. My particular problem has to do with the specified insulation between between TNV-3 circuits and SELV circuits, although the question about Annex ZB applies to other national deviations as well. I will use the TNV/SELV issue as an example. Clause 6.2.1.2 of EN 60950 specifies basic insulation between TNV-3 and SELV circuits. However, in Annex ZB, it states that Norway and Sweden require supplementary insulation. Annex ZB states that "for the countries in which the special national conditions apply, these provisions are normative. For other countries they are informative." I am trying to understand how this distinction is applied for CE marking. I thought that the intent of CE marking was that products could be evaluated against "harmonized" standards and then have the CE marking applied. I thought that products with the CE marking were allowed to move freely among the member countries in the EU. Annex ZB seems to complicate this simple interpretation. My tentative conclusions about the above situation are: 1) A manufacturer who intends to market his product in a list of EU countries that excludes Norway and Sweden can apply the CE marking to a product that has only basic insulation between TNV-3 and SELV circuits. 2) A manufacturer who intends to market his product in a list of EU countries that includes Norway or Sweden can only apply the CE mark if the product provides supplementary insulation between TNV-3 and SELV circuits. The above two cases result in products that each bear identical CE marking, but one of them (case 1) is technically illegal for use in Norway and Sweden. From looking at the product marking, there is no way to determine that the product in case 1 should not be used in Norway or Sweden. I suppose that this distinction could be made in the user manual. I also presume that the manufacturer in case 1 would be obligated to ensure that the product is not offered for sale in Norway or Sweden. Maybe this is enough to comply with the letter of the law, but I suspect that it would be easy for the product in case 1 to find its way into Norway and Sweden. Prior to the adoption of CTR 21 for analog modems, the above issue was largely academic, since individual national approvals and the corresponding national labels were still required for connection to the PSTN. However, now that CTR 21 has been adopted, I expect there will be a rush toward "full" CE marking (including the crossed hockey sticks) of analog modems. National approval labels will no longer be required. I think this will bring additional attention to the situation I have described above. Can anyone offer some some insight into how this situation should be handled? Is my interpretation correct? Any comments would be welcome. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 325 Highland Avenue Winchester, MA, USA 01890 781-721-2848 (voice) 781-721-0582 (fax) --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], or [email protected] (the list administrators).
