I just moved into a new (to me, but built in 2008) condo and am assessing the telecom situation. I'd like to get Ethernet connectivity to as much of the unit as possible, for wireless range extenders (or LAN parties...)

It seems like the builder has run an assortment of unterminated wires to a 'telco closet'. There are 3 blue Cat5e cables, one white Cat5e, and one grey Cat5e.

enter image description here

Around the unit there appears to be an RJ11 that terminates the other end of the white cable with four wires:

enter image description here

Plus two RJ11 jacks that look the same, except with a blue cable:

enter image description here

Plus two RJ11 jacks that seem to have some sort of daisy chain situation going on with the blue cables:

enter image description here

Given that we haven't used a phone landline for at least a decade now, I'd like to repurpose the existing Cat5e wiring for Ethernet, installing a router/switch in the closet. I'm trying to figure out answers to the following questions:

  1. Is it against building code or otherwise a bad idea to disable or remove some or all of these RJ11 jacks and replace them with Ethernet, using the underlying Cat5e cables?
  2. Why are some of the RJ11 jacks terminated with a single cable and others daisy-chained?
  3. There are 3 blue wires coming out of the telco closet and 6 blue wires emerging elsewhere in the house (2x single and 2x double). This seems to imply a logically impossible daisy-chaining situation to me, and I've looked very hard and not found any other RJ11 jacks. How could it be wired this way?
  4. What is the best way to test a hypothesis of the actual wiring without potentially frying a device accidentally?
  5. The grey Cat5e doesn't seem to emerge anywhere in the house. What might it be for, e.g. it is connected to a central patch panel somewhere in the building? Is this a common situation?

Slightly related question: How can I convert Cat5e wired sockets to Ethernet?

1 Answer 1

  1. I'm no pro, but I'd say you can do as you wish with low voltage cable
  2. I'd guess the daisy chaining was a poor mans way of propagating the phone cable without running it back to the closet.
  3. Yeah, see the last answer
  4. I'd remove the phone jacks and short out two of the pairs with clip leads. Then use a continuity tester to map out the cables.
  5. Does the grey one lead to the attic somewhere?

I'd say you can terminate the cables you need with wall plates in the rooms, RJ45 jacks in the closet and if you need additional service to one of the daisy chained rooms, you can add a switch where needed to continue the chain. Mount the switch to the wall close to the wall jacks to get it out of the way.

  • Yes, daisy chaining is not unusual for phone wiring. But it won't work for Ethernet.
    – AndyB
    Aug 28, 2021 at 19:23
  • @AndyB Okay, so I have the same thing - 3 sets coming to one port (the type with the screws on the back as shown in OPs last photo like you were talking about not being unusual. I just added an RJ45 port and am trying to leave the RJ11 (so I am installing an additional run without disturbing the existing daisy-chained RJ11 via a 2 keystone wall plate) but am very confused how I am supposed to terminate (specifically punch down) 3 cables. I didn't even know that was possible, but it was done easily with the screws and I can't seem to "upgrade" or at least update that port.
    – Cfomodz
    Sep 10, 2021 at 6:43
  • @Cfomodz It looks like you got good answers when you asked it as a separate question.
    – AndyB
    Sep 11, 2021 at 19:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.