Hi Pete:

 

When considering how 62368-1 is applied to an Ethernet cable, it's necessary
to look at how the Ethernet cable is used.  Following is how I interpret
some common examples:

 

1)      Ethernet cable used entirely with a building:  No transient test

2)      PoE cable that goes outside the building to a floating PoE camera:
No transient test

3)      Ethernet cable that connects two separate buildings:  Transient test
(1500 V) applies, common-mode only

 

My reasoning is based mostly on this note from Table 13 in the 3rd Edition:

 



 

Keep in mind that if the Ethernet port complies with the isolation
requirement in 803.3, it will have common mode isolation that is sufficient
to withstand a 1500 V transient.  Most manufacturers' designs meet the 802.3
isolation requirement, but some don't.

 

If your application involves an Ethernet cable that has different ground
references at each end, the 62368-1 isolation test is 1500 V, but experience
has shown this is not always sufficient.  I wrote an article on this topic
in 2017:

 

https://randolph-telecom.com/wp-content/uploads/2021/03/Designing-Ethernet-C
able-Ports-to-Withstand-Lightning-Surges_IN-1300.pdf

 

 

Joe Randolph

Telecom Design Consultant

Randolph Telecom, Inc.

781-721-2848 (USA)

j...@randolph-telecom.com

http://www.randolph-telecom.com

 

-----Original Message-----
From: Peter Tarver [mailto:ptar...@ieee.org] 
Sent: Friday, July 9, 2021 1:13 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Surges on Ethernet ports under 62368-1

 

Good morning.

 

61368-1, Table 14 (2nd ed) or Table 13 (3rd ed) discusses transients to be
applied to conductors considered external circuits.

 

Whereas in 60950-1, these tests generally applied to conductors falling
under Clauses 6 or 7, the scope of the applicability of the testing appears
to have expanded to include simple IEEE 802.3 circuits that exit a building
structure, which were excluded from such testing under 60950-1 (where ITIC
had dictated to test houses, "thou shalt not place transients on mine
network circuits").

 

As a relative newcomer to 62368-1, I am looking for confirmation that the
above is accurate.

 

 

Regards,

 

Peter Tarver

 <mailto:ptar...@ieee.org> ptar...@ieee.org

 

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