Thanks Tania, I appreciate the support.
Answers to questions like these are VERY important in trying fit telco owned equipment into the IEC 950 based standards which were written from the CPE perspective. Jim Jim Wiese ADTRAN, INC. 901 Explorer Blvd. P.O. Box 140000 Huntsville, AL 35814-4000 256-963-8431 256-963-8250 fax [email protected] >---------- >From: Grant, Tania[SMTP:[email protected]] >Sent: Wednesday, April 29, 1998 12:41 PM >To: "[email protected]" ; "Jan Purwin" >Subject: RE: UL 1950 3rd, and IEC 950 > > Right! > > But can the UL1950 (or its IEC derivatives) standards take into > account NEBS requirements unless they formally reference those > standards, which they have not done? > > Thus, Jim's premise still has validity. So, is the TNV1/TNV3 > separation requirement nothing more than "cover my...." > on the part of the IEC/EN/UL...950 standards? I don't know. > But I still consider Jim's question a very good one that needs > an answer. > > Tania Grant, Lucent Technologies, Octel Messaging Division > [email protected] > >______________________________ Reply Separator >_________________________________ >Subject: Re: UL 1950 3rd, and IEC 950 >Author: "Jan Purwin" [SMTP:[email protected]] at CORP >Date: 4/29/98 8:13 AM > > >Jim you are not quite right. >There is a lot of protection and separation that are defined in NEBs >and >NEDS standards. >Those are incorporated into the equipment that is installed in a central >office. > >If you have a chance to go to typical central office and look how RBOC >installes equipment you would >had better idea about protection separation and equipment construction >that >goes into CO equipment. >Jan Purwin > >JIM WIESE wrote: > >> I am looking for some guidance in understanding the separation >> (creepage/clearance) requirements with regard to TNV circuits in UL >1950 >> 3rd and IEC 950 and its derivatives. >> >> Why is there a requirement that TNV circuits have basic insulation >> between TNV1 and TNV3 circuits? >> >> I am asking the question for the following reasons: >> >> The telco network provider is generally exempt from listing >requirements >> altogether. They have no restrictions on separation of circuits and >> have TNV 1, TNV 3 and span powered circuits (200 VDC HDSL, T1 etc.) >> intermingled at the central office in channel banks, cross connects >etc. >> They provide these services via cables that are spliced, cross >> connected and intermingled in the Outside Plant. They are also >> intermingled without regard to spacings at the distribution and >> demarcation points. Since it is a fact that these services are not >> separated by "basic" insulation, why would it be important to separate >> TNV1 and TNV 3 in the terminating equipment. To me it seems like a >> chain made of paper, and at the end of the chain the standards are >> requiring a steel link. >> >> Secondly, do the standards assume that faults of TNV 1, TNV 3, and >other >> high voltage telco services could be faulted by the telco provider >> inadvertently and therefore this type of fault is accounted for by the >> dielectric test (and other restrictions) between SELV/chassis and TNV >1, >> and TNV 3. >> >> Any input would be appreciated and helpful. >> >> Thanks, >> >> Jim >> >> Jim Wiese >> ADTRAN, INC. >> 901 Explorer Blvd. >> P.O. Box 140000 >> Huntsville, AL 35814-4000 >> 256-963-8431 >> 256-963-8250 fax >> [email protected] >
