For context, this is in France, in a building where this part of the cabling is probably around 25+ years old.

My apartment has an intercom to answer and open the building door. It is quite simple: there is a single circuit for both the voice and the trigger to open the door. The door is opened by short-circuiting the circuit (during this time you obviously cannot talk).

The original place of the intercom was right next to the door (this is what I saw at my neighbor's), it has been moved elsewhere by a previous owner. At the place where the old intercom was there is a junction box with a bunch of open-ended cables and two wires that have been patched to move the intercom.

What I do not understand is how they have been patched, specifically the something that connects them

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The wires do not come out of the connectors when pulling (but I did not try to pull too hard)

There is a 10V tension between the blue and white wires, in line with the expected voltage for the intercom.

My question: what are these connectors? Can I swap them for a WAGO splicing connector?

  • Any chance they light up? The wires do not look like they connect/touch inside. Maybe for a hearing impaired person?
    – crip659
    Jan 2 at 18:22
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    @crip659: no they don't. If you mean "they would light up so that a hearing impaired person can visually see that someone is ringing then no - this is a closed box and the connectors are inside.
    – WoJ
    Jan 2 at 18:25
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    @crip659 there's a curved metal piece in there that pinches the two wires. It's easier to see it in the second picture and bottom Scotchlok.
    – KMJ
    Jan 2 at 18:34
  • @KMJ It's the metal piece acting as in insulation displacement connector (IDC) which is important. Nobody else has pointed this out, and you've missed the opportunity to put this in an answer. Jan 3 at 7:37
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    Is there a specific issue you're trying to correct by redoing these splices, or is this a matter of "I don't know what it is and I want to replace it with something I'm familiar with"? In America, we have a saying: "If it ain't broke, don't fix it". i.e. you could cause more problems by trying to change something that works simply to change it...
    – FreeMan
    Jan 3 at 13:45

2 Answers 2


These look like an insulation displacement connector. 3M makes a comparable item they call Scotchlok; several other connector makers also offer something comparable. The Scotchlok name is semi-genericized in that some trades people call all connectors of this style by that name. These are permanent connectors. The conductors are inserted into holes in the housing, then the housing is squeezed with pliers so that a movable portion is forced in to engage and connect the conductors.

Yes it looks as if WAGO 221 should do the job equally well.

You can confirm whether these are connectors by cutting one off and measuring resistance between the cut leads. On the outside change we both were wrong and these aren't a connector -- splice the cut wires back together with two of your WAGO 221. :-)

  • I just measured the voltage between the white/blue wires - it is 10V as expected for an intercom.
    – WoJ
    Jan 2 at 18:31

Those are telephone splice connectors. You slide both wires in and press the button, which joins 2-4 wires electrically. They are often filled with a water-repellent goo, so they work outside as well as inside.

You can replace them with a WAGO connector, but I've found these to be more reliable on smaller gauge wire.

  • 6
    Speaking to reliability: on low voltage these are incredibly reliable if gel-filled. They are effectively a permanent splice.
    – KMJ
    Jan 2 at 18:35
  • 6
    They look like they've been installed incorrectly - the insulation has been removed prior to the wires being inserted; that isn't needed, and may possibly make the connection less reliable (eg if the wire gets nicked/flattened in the process of removing the insulation).
    – psmears
    Jan 3 at 11:04

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