From: Rick Cooper <[email protected]> Subject: RE: TNV-1 vs SELV for unit with Outdoor Coaxial Cable Connection
Peter, Another 2 cents worth: About item 2, in the 9 November 1995 "Report on the meeting of the Industry Advisory Council of UL for ITE...," this very issue is addressed. UL's position at that time was to simply impose the voltage surge tests of IEC 65, sub-clause 10.1, or UL 1492, section 87, to all ITE with provisions for connection to outdoor antennas. No particular construction was specified and no requirement for an antenna discharge path was suggested. Compliance with the tests seem to be all that is required. Continuing, in the 10 June 1998, "Report of the meeting of the Industry Advisory Council of UL for ITE...," this issue was revisited. In a discussion about multi-media equipment that falls within the scope of UL 1950, it was stated that hazards not addressed in the base standard be evaluated against the requirements of a supplementary standard. The specific example given was the application of the votage surge tests. About item 3, in the same 10 June 1998 report mentioned above, UL stated their position on outdoor-use equipment and addressed coaxial cable requirements for such equipment. While your question appears to involve indoor-use equipment with connections to an outdoor antenna, I think the guidelines provided are useful. Basically, for the U.S., it seems necessary to provided a cable that is Listed for the purpose or otherwise Listed and evaluated for the application so that authorities having jurisdiction can judge suitability against the requirements of the National Electrical Code. Hope that helped with 2 of your questions. Rick Cooper MET Laboratories, Inc. 410-354-3323 Ext. 331 > ---Original Message----- > From: [email protected] [SMTP:[email protected]] > Sent: Tuesday, December 01, 1998 4:50 PM > To: [email protected]; [email protected] > Subject: TNV-1 vs SELV for unit with Outdoor Coaxial Cable > Connection > > Dear All, > > A CO equipment with a 48 Vdc nominal supply has coxial cable > connection to an outdoor transmitter. I have the following questions: > > 1. The coaxial cable output is conductively connected to the input. > It carries the same voltage and an amperage of 1 A (limited to 3 A > max). Assuming the input supply tolerance not to exceed 60 Vdc, > does everyone agree that this is SELV? Some of you may argue > that it is TNV-1 since it is exposed outdoors! Based on the 950 > definition of TNV, to the best of my understanding, the circuit is not > > a telecommunication network voltage circuit. > > 2. 950 does not discuss protection of the equipment or user from > lightning. It should be noted that the unit also has user accessible > SELV interfaces. What type of tests or construction would you > recommend for the coaxial interface? I believe the Impulse Tests in > IEC 65 or in UL1492 should be highly recommended. > > 3. Are there any requirements for the outdoor coaxial cable? > Should it be Listed cable for North America and if so, what type of > Listed cable? Should it be Approved for Europe and if so, what type > of Approved cable? > > Assuming the power output to the cable was limited in accordance > to UL1950/EN 60 950 (ie output was limited to Class 2), should the > cable still be Listed or Approved? > > 4. Assuming the input tolerance now to be max 72 Vdc (a > secondary hazardous voltage circuit) which also makes the coaxial > output connection 72 Vdc, does anyone see a problem with this > type of circuit being transmitted through a coaxial cable to the > outdoor transmitter? > > Thank you all. > 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: [email protected] > Visit our Website: http://www.itl.co.il > > --------- > 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], [email protected], or > [email protected] (the list administrators).
