One reason against the use of shielded twisted pairs in residential environment is the possibility to create a group loop between equipments, as discussed in Shielded Twisted Pair (STP) termination and grounding.

Some PCB mounted RJ45 ports are magnetically coupled through common mode chokes (Why Are Ethernet/RJ45 Sockets Magnetically Coupled?). However, non-isolated ports do seem to exist.

The common mode chokes should at least provide some degree of isolation for ground loop. What level of isolation can they provide? Assuming the ports on both ends have the chokes, until what point will they no longer be able handle the group loop and an isolation transformer is required?

  • "in residential environment" Unfortunately, questions about home/residential networking are explicitly off-topic here. This is actually a question to ask on Electrical Engineering, where you have the link. The actual end-devices are off-topic here.
    – Ron Maupin
    Commented Jul 8, 2020 at 22:13
  • 1
    @RonMaupin I believe that the question itself is general enough to not be limited to residential networking, as the residential network is merely an example on when a ground loop can be created.
    – Mys_721tx
    Commented Jul 8, 2020 at 22:16
  • 1
    Your question is about something that network engineers really do not do. It is an electrical engineering problem. Remember that ethernet is an IEEE (Institute of Electrical and Electronics Engineers) set of standards, and how and end device is made is not on-topic here.
    – Ron Maupin
    Commented Jul 8, 2020 at 22:20


Browse other questions tagged or ask your own question.