Another frequently-searched phrase according to Google is “how to fix cut underground phone line”

It Happens Frequently – Don’t Worry.

Only last night I was contacted by a home-owner.  His builders had unexpectedly met a cable when doing some groundwork. The situation was the usual “we are holding the builders up/we need to get out internet back on/what are these wires?/how do I joint them?” mild panic.

Technically, You Have Damaged Openreach’s Infrastructure.

(“Wait a minute! You said “don’t worry” – now you are trying to panic me!”) Not so. I just need to make this absolutely clear. The official line is that you must call in Openreach to fix it.

Therefore, anything in this blog from this point on should be read as hypothetical.

It is written from the basis that, due to a fundamental change in responsibility, you were allowed to fix it yourself.  Currently, only Openreach should carry out repairs.

(Meanwhile, do independent engineers carry out unofficial repairs on Openreach’s damaged cables? I understand that they do. 😉 )

What Would Openreach Charge? How Fast Can They Attend?

At least £130.00 to turn up.  Then an hourly rate of approximately £85.00, plus parts (£50.00?). You may wait upwards of five days to get a visit.  There is no “fixed fee” repair, so costs are not predictable. Yikes.

What Would an Independent Engineer Charge (Hypothetically)?

Possibly around 30 to 50% less. Furthermore, they might be able to respond quickly.

How Is The Damage Repaired?

Openreach may use a “mechanical joint closure” (A what?)

One of these…

They are two halves of a very strong plastic “Easter Egg” with a hole at each end. Furthermore, the two halves equipped with multiple high-grade flexible seals. Finally, they are clamped together very firmly. Therefore, they make a highly-waterproof chamber. However, the wires themselves will have first be jointed by jelly crimps and tested (of course).

What If I Wanted To Repair The Damage Myself (Unofficially)?

First Trace Your Wires

Identify each pair of wires – this is easier said than done. Internal wires which have a clear colour identification as a pair, (blue/white-white/blue). However, underground cables will have “solid” colours only (blue-white, orange-white, green-white, brown-white, grey-white). The job suddenly got more difficult.

The basic way of proving which solid white colour wire goes with which solid coloured wire is by simply seeing which ones are twisted together when viewed in a suitable length. Yes, really. This is the time-honoured professional cable-jointer’s method. However, if the cables have been truly mangled, and you can’t strip any more of the sheath back (or don’t have the length of spare cable to do it),don’t worry. Fortunately, there are alternative ways of finding which pair is the one that is carrying your service.

  • Use the detachable front-plate of your master socket to attach the most likely pair of wires to. If you plug in a phone and hear dial tone – success!

  • Use a multi-meter set to DC voltage to check for the 50V DC across the live pair.

Joint The Wires.

Use jelly crimps and try and joint all of them. Check in your premises for dial tone. N.B. This is essential – your broadband will work on one wire but slowly, forever. Make sure both are connected by checking for dial tone. Simply looking at the green light on your broadband router won’t be sufficient.

Find a Suitable Joint Enclosure

The MJC, Openreach-type joints occasionally pop up on eBay. Tyco Electronics produce one that suits the 5-pair cable feeding houses perfectly. Try them direct in Swindon.

Here’s the MJC, with cables jointed, ready to be snapped shut.

Alternatively, the resin-sealed underground electrical joints used by electricians can be adapted to work, so I understand. They are used reliably on highway lighting, where they are exposed to all sorts of potential damp and pressure. Furthermore, they are more readily available. It’s absolutely vital that the jelly crimps are encased in something totally moisture-proof. If you can imagine them suddenly being encased in the very middle of a hard butterscotch-type sweet, you’ve got some idea of how effective they are.

Apart from the Openreach-specification MJC joints mentioned above, I can’t think of anything else, apart from a resin-fill joint, that will offer the same degree of protection. Heat-shrink tubing may not be 100% impermeable if it fails to seal around the cable sheath ends. I’ve dug these up deliberately and found them wide open. Most of all, don’t even think about using yards of insulation and gaffer tape. Water will always find a way if there’s a weakness.

Re-Test For A Dial Tone Before You Fill In The Hole.

It’s a little too late, but it saves having to dig again, and risk hitting the cable.

An Even Better Way?

Call in your local independent (probably ex-BT) engineer to do the job for you, as they will be well familiar with the question “How to Fix Cut Underground Phone Line” . If you are looking for an engineer, please drop me a line, as I network with many across the UK. If you are in the North East, it might be me. Please get in touch!