Not quite sure what this is, but I need to move it up slightly to fit my baseboards. Is this an electrician job?enter image description here

Update: Unscrewed and uncovered this, is it safe to assume it’s non functional? (This is a shared building I just moved into my unit I have no telephone but I’m not sure if this serves others) enter image description here

  • 11
    It's telephone wiring. Do you have telephones?
    – jay613
    Commented May 31 at 18:40
  • 4
    It's functionally connecting the blue-white pair to the right with the blue-orange pair to the left. Without knowing where the cables go, it's impossible to say if it's in service or not without some testing. It's neither non-functional nor frayed per these pictures, just badly stripped cable jacket and Not Done In a Neat & Professional Manner. It shouldn't be servicing other units being run in your unit, but who knows what sort of sloppy job was done converting the space?
    – Ecnerwal
    Commented May 31 at 19:31
  • 7
    @RMDman - a ringing US POTS phone sends 90V AC. How I know this? Got bit as a kid playing with phone lines.
    – Tiger Guy
    Commented Jun 1 at 4:49
  • 2
    Follow the wires and see where they go... If it is an official BT installation they very much likes surface mounting the entire setup for the whole cable run. If they have been chopped off already there is no need to move, just (unpermittedly) remove.
    – matt
    Commented Jun 2 at 14:53
  • 2
    Go ahead. It's easier to ask forgiveness than to ask permsssion. Commented Jun 3 at 4:06

4 Answers 4


It's a telephone jack, (or surface-mount junction box) albeit a poorly installed one. Apparently British Telecom, between 2003 and 2019, by the logo.

There should be no hazard to moving it. Or removing it, if you don't have landline telephone or data service.

  • 13
    Or an alarm system that uses it to notify the monitoring service.
    – HABO
    Commented May 31 at 19:08
  • Thanks, this building was an old office that’s been split into studios, I have no telephone but can’t speak for the other units. I just uncovered to find frayed wire
    – Brent
    Commented May 31 at 19:24
  • Your uncovered picture shows one pair of wires connected between the two cables. So there is the possibility that the cabling is in use. Commented Jun 3 at 13:04

If you can move it without stressing the wires, there is no harm. Otherwise, it's most likely a low voltage POTS (Plain Old Telephone Service), or less likely, an alarm or other signaling circuit.

To determine which one and whether it’s in use:

  1. Put your meter in DCV mode and measure between the two wires that pass through. A reading of 12-60 Volts (varies with country and system; 50 in UK, 48 in USA) assume it is an active phone circuit.
  2. Put meter in VAC range and measure again. If >6 VAC, assume it is an active signal or control circuit (e.g., doorbell, door latch, entry chime).
  3. If 0 VDC and 0 VAC, put meter in resistance mode and measure again. If <20K (20,000) Ohms, assume it is an active alarm circuit.

If none of above, you should be able to disconnect it with no harm. Disclaimer: most likely is not the same as definitely, and one can’t be sure without tracing the wires to both ends.

  • I wouldn't have thought to check resistance, I'd assume that an alarm would show some type of voltage also, but I guess not?
    – Xen2050
    Commented Jun 2 at 2:02
  • 1
    Difficult to measure between the wires since they're joined inside a sealed single-use connector; you'd need to either break (and possibly re-make) the connection, which requires replacing the connector, or use some sort of insulation-displacement technique such as a bed-of-nails clip.
    – psmears
    Commented Jun 2 at 21:04
  • 1
    @Xen2050 Most alarm circuits use a normally closed switch, thus no voltage across the wires until triggered. Opening the switch or cutting a wire triggers the alarm (that's why they use NC). The crook's workaround is to short the wires together instead of cutting them. The alarm company's next step is to include a resistor in series at the switch, whose value is monitored at the control center. A deviation in resistance triggers the alarm. The current source is fairly small, thus the voltage drop quite small as well, likely not easy to tell from noise on the line.
    – MadMonty
    Commented Jun 5 at 16:22
  • @psmears or just shave a bit of insulation off each wire
    – MadMonty
    Commented Jun 5 at 16:24

It's BT Openreach telephone wiring but these are also used to deliver DSL broadband (ADSL or VDSL/FTTC). You and your neighbours may not have a telephone but they may have broadband. I would not disconnect it unless you are sure that there is nothing on the end of it.

In the most recent Openreach implementations (SOGEA and SOTAP) there is no analogue phone service on the line any more, only DSL, and the phone service is provided via VOIP ('digital voice') This means you may be unable to measure line voltage or detect a dialling tone. I believe there may be still some 'wetting' voltage on the line (to detect/prevent high resistance faults) but not necessarily full ringing voltage as mentioned in another answer.

Legally speaking it belongs to Openreach and that would count as damage to their property. However in practice it would likely be fine to move it a short distance without disturbing the wiring, since any engineer who visits is not going to know how it was originally installed.

  • Yes. Any damage to it on purpose might be vandalism. Just be careful not to snag anything on it or get it wrapped around, say, your foot while walking briskly away from the wall. Have a pet? Make sure they don't go chewing on it either, such as behind a chair in the corner where it enters your apartment, because at that point the wire is ruined and you'd just have to coil it up out of the way.
    – simpleuser
    Commented Jun 7 at 21:23

Looks like it's a BT junction box, should be perfectly safe to move as long as you're careful not to break the insulation. However, it may not actually be legal to move it. The fact that only 2 wires are connected means that it is likely on BT's side of the master socket, which means that the wires and box belong to BT and you would need to call out a BT (or OpenReach) engineer, which they will charge through the nose for.

Having said that it's unlikely anyone will know if you're just moving it up a couple of inches as long as you don't break the wires and disrupt someone's service.

  • It's very unlikely to be on the BT/OR side of the infra. It's almost certainly just a junction box for a telephone extension within the property. Commented Jun 3 at 16:14
  • If it were for an extension inside the property, then I would expect to see 3 wires connected, not just 2 - only connecting 2 wires on an extension will make the extension not ring properly. Also it's quite rare to see those connectors on extension wiring
    – rhellen
    Commented Jun 4 at 13:48
  • I see. We've got numerous of these boxes around our home for extension wiring, which I assume was installed by BT rather than a third party. Commented Jun 4 at 16:56

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