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Black wire is coming from a hole to the brick wall so possibly outside. It looks like it’s falling apart and attached beside the main circuit breaker panel for the house. No idea what it is.

  • 6
    +1 for making half of DIY.SE feel really old right now....
    – Criggie
    May 27, 2022 at 23:41
  • I've suggested an edit to explain that it's not "attached to a switchboard" but is attached to the wall next to the circuit breaker panel for the house. A "switchboard" is (usually) something entirely different it's not surprising someone who doesn't know what a landline is wouldn't know that a switchboard is a central panel to which you connect all of the telephones in (usually) an office or other business. ("Switchboard" is also used for industrial power distribution systems, but I've never heard it used for residential panels.)
    – cjs
    May 29, 2022 at 12:14

2 Answers 2


That is a telephone wire.

From roughly 1880 to 2010 people who were not in the same place and wanted to speak, did so mostly using telephones connected by pairs of copper wires.

The black wire contains one or more such pairs and brings them into your house from a pole or underground. The beige plastic box connects those to pairs of copper wires that run all over your house. The three beige wires and the grey one probably go off to your kitchen, bedroom, living room, etc. where there once would have been telephones.

On the left: a telephone. On the right: A patch bay for telephone wires, similar to what we would call a "router" today.

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  • 9
    I love the inclusion of a picture of a telephone! It's even a rotary, so kids these days might have a chance of understanding the term "dial a number".
    – FreeMan
    May 26, 2022 at 13:30
  • 7
    ...at 110 bits per second! With your phone handset jammed in the acoustic coupler! Then 300, then 1200, then 2400, 4800, 9600, 19.2K on up to about 56K, which was as good as you could do on this wiring until DSL came along, where you might get 1-7 M depending how close you are to the central office, and how bad the wiring is between you and them.
    – Ecnerwal
    May 26, 2022 at 13:31
  • 3
    If you happen to have a landline phone, plug in and check for dialtone. In some areas even phone lines without active paid service are maintained at a minimum level of service to provide a way to call emergency services (those calls will go through, others will not.) There's no particular need to remove it, or harm in leaving it, regardless.
    – Ecnerwal
    May 26, 2022 at 13:54
  • 5
    That's assuming your phone company even offers that service in your area. Verizon local to me is like "FIOS? yeah, you see the ads but we can't be bothered to put that in where YOU live. Have some crappy overpriced slow DSL on 80 year old wires." Most folks use cable internet, where the company is hated just as much, but the speeds are higher for similar money.
    – Ecnerwal
    May 26, 2022 at 13:59
  • 8
    While this is starting to get chatty, I just have to add that I grew up in a home with a "party line". I'll bet no younger person knows what that is. There were 2 other parties on the line, each with a different ring pattern so we knew if the incoming call was for us or the others. Picking up the phone to make a call often led to realizing one of the other parties was already on the line and our call would have to wait. You could literally hear their conversation. ...just chiming in for your enjoyment. May 26, 2022 at 17:35

Landline Telephone. The black wire is the drop wire from the pole or outside interface.

The cover could be screwed back on.

It's not connected to the electricity supply at all, other than there might be a grounding wire (but none is visible in this picture, and there's no connection between the two systems in this picture, nor would there normally be such a connection.)

They are just in the same general area, which is common.

  • Thanks! I am embarrassed I didn’t think of that :)
    – rausted
    May 26, 2022 at 13:27
  • 4
    Land lines work when the electricity is down.
    – Xanne
    May 27, 2022 at 3:19
  • 3
    @Xanne: Telcos seem to put much less effort into ensuring that's the case than they used to.
    – supercat
    May 27, 2022 at 17:50
  • 3
    @Xanne Land line provides its own voltage, around 48 VDC (probably depends on where you live). Granted, if the reason the electricity is down is because someone knocked down a utility pole, you'll likely lose both power and land line, since they run on the same poles in many places. May 27, 2022 at 17:52

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