>From http://www.verizonnebs.com/TPRs/VZ-TPR-9305.pdf

7.2.12.1.  
 
"Verizon has revised its long-standing installation practices and now allows
shielded cables to be grounded at both ends when in the common bonding
network. Therefore, the GR-1089 Intra-building Lightning Surge Tests
(Telecommunications Port) statement that "these tests do not apply if
intrabuilding wiring (cabling) is shielded and the manufacturer's
documentation states that both ends of the shield must be grounded" is now
applicable for equipment that will be installed in the CBN."

David



________________________________

        De : emc-p...@ieee.org [mailto:emc-p...@ieee.org] De la part de Dan 
Roman
        Envoyé : Tuesday, June 02, 2009 9:42 AM
        À : Joe Randolph; EMC-PSTC@LISTSERV.IEEE.ORG
        Objet : RE: [PSES] GR-1089 intrabuilding surges question
        
        

        Even with shielded cables a test is still required in GR-1089.  It is
essentially a test of how well the shielding works.  The test is designed such
that if the shielding is not great at least part of the surge ends up on the
cable conductors.

         

        I have found very few Ethernet ports on standard servers survive the 
surge
with unshielded cables.  Most Ethernet transceivers need to have some "above
and beyond" surge protection added in order to guarantee their survival.

         

        Some customers I have dealt with do not allow the use of shielded 
cables on
Ethernet ports.  As with most things in NEBS it all comes down to the
customer's requirements.

         

        Dan

         

        From: Joe Randolph [mailto:j...@randolph-telecom.com] 
        Sent: Monday, June 01, 2009 9:33 PM
        To: EMC-PSTC@LISTSERV.IEEE.ORG
        Subject: Re: [PSES] GR-1089 intrabuilding surges question

         

        On 6/1/2009, Gelfand, David wrote:
        
        
        

        GR-1089 clause 4.6.9.2 intrabuilding surge test has an exemption for
        shielded cables grounded at each end.  This is supported by Verizon
        document http://www.verizonnebs.com/TPRs/VZ-TPR-9305.pdf clause
        7.2.12.1.  
        
        Does this reflect current practice?  

        
        
        Hi David:
        
        So far I have always managed to avoid using this exemption, since my 
gut feel
is that it might create more problems than it solves.  However, as the
requirements state, this is an allowable option for an installation with a CBN
grounding scheme.
        
        These days most central offices use a CBN grounding scheme, but there 
may be
cases where an IBN system is still in place.  Technically, the exemption can
only be used in a CBN system, although this may be hard to control in practice.
        
        I don't know what sort of intrabuilding cable you are addressing, but 
if it
is something as simple as an Ethernet cable, it should not be necessary to
invoke this exemption.
        
        
        
        

        Joe Randolph
        Telecom Design Consultant
        Randolph Telecom, Inc.
        781-721-2848 (USA)
        j...@randolph-telecom.com
        http://www.randolph-telecom.com <http://www.randolph-telecom.com/> 

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