Cable faults
Cable fault location on telecoms, data and cable TV lines in Vienna, Lower Austria and Burgenland as well as parts of Upper Austria and Styria
The telephone is dead, the line to the outbuilding no longer carries data, the television picture drops out in wet weather. With buried telecoms, data and cable TV lines the fault is almost never where you expect it, and laying a new cable would be the most expensive answer. CFT surveys in the fault position, marks it on the surface and hands over a written finding; the repair is then carried out at one point instead of along the whole route. Report the failure on +43 (0) 2252 53169 or in writing to office@cft.at, and we will clarify the cable type, access to the ends and the appointment.
What we do on site
We disconnect the active equipment and measure section by section between two accessible points. The measured distance is set out along the located route and the point is marked. You receive a damage report as a PDF with which the area to be excavated can be limited; the repair is carried out by your electrician.
Key facts at a glance
| Methods | Time domain reflectometry (TDR), bridge measurement (Murray loop), twist method on twisted-pair cables, electromagnetic cable locating, cable identification in trench and cable tray |
|---|---|
| Application range | Buried telecommunications and telephone lines, data and network cables, coaxial cable TV lines between the amplifier point, the taps and the customer handover point |
| Duration | 2 hours are the minimum, each additional complication one hour more. One or two fault locations are usually covered. |
| Result format | Damage report as a PDF |
| Service area | Vienna, Lower Austria and Burgenland as well as parts of Upper Austria and Styria; from the Erding site additionally Bavaria and Baden-Württemberg |
For you as a private customer
The failure shows itself as a malfunction, not as a power cut: the television picture freezes or disappears, the data rate collapses, the intercom hisses. Between house, garden shed, garage and street there are often lines dating from the time of construction whose route nobody knows any more. The expensive part is not the repair but the search: anyone who digs without measuring opens up paving, lawn and driveway on suspicion. We work the other way round – measure first, then mark, then open up – and carry on with the cable that is already there.
For you as a business
Cable TV operators, telecommunications providers, IT service providers and managing agents usually do not have the measuring equipment for fault location in their own fleet. We come in as a measurement contractor without taking over the job: we locate, you repair. The problem is not the failure but how long it lasts – a run is out of service for as long as the fault position is unknown. The finding is documented in such a way that it stands up in a site diary, a property file or a fault report.
How the job runs
1. Recording the fault pattern. You describe which function fails and whether the failure is permanent, intermittent or weather-dependent. We clarify by telephone which connection points have to be accessible and who isolates the run.
2. Disconnection and initial measurement. Active equipment is disconnected, because measurement takes place on the free run: amplifiers, modems and end devices are left out. We record which core or which section is affected and whether there is an open circuit, an earth fault, a short circuit or a screen fault.
3. Prelocation and line tracing. The measurement gives the distance of the fault position from the measuring point. We then trace the route at the surface, because only distance and route together give a point.
4. Pinpointing and report. The position is narrowed down, marked and photographed. You receive the damage report with readings, TDR trace and route drawing; the repair is carried out by your technician or by the network operator. CFT does not carry out repairs.
Where in the network measurements are taken
Cable TV and data networks are built up in sections, and these sections are also the measuring points: from the amplifier point via the taps to the customer handover point. Measurement is carried out section by section between two accessible points, because otherwise every tap and every amplifier is superimposed on the measurement. The same applies to telecommunications lines with a cross-connection cabinet and junction box. The first question before the appointment is therefore not which instrument we bring, but which points may be opened and disconnected, and who is allowed to do so.
Equipment and methods
Time domain reflectometry (TDR) on coaxial cable
Coaxial cables have a defined characteristic impedance, and time domain reflectometry depends on it: a short pulse is fed in, every deviation reflects part of it, and from the transit time of the echo the instrument calculates the distance. A crushed section, a damp plug connection or a torn screen each show up differently. The limitation: the method gives a distance along the cable, not a position in the garden, and with long, heavily attenuated runs or several discontinuities one after another the picture becomes unclear.
Bridge measurement (Murray loop) on twisted-pair telecommunications and data cables
Bridge measurement is a comparison of resistances: at the far end the faulty core and a sound core of the same cable are joined into a loop; the fault position divides it into two sections whose resistances are in the same ratio as the corresponding lengths. Twisted-pair cables offer the most favourable starting point for this, because all the cores have the same cross-section and the same length, so the reference for comparison lies alongside within the same sheath. Its limitation: it requires access to both ends and a sound return conductor, and an undocumented junction box falsifies the length.
Twist method on twisted-pair cables
Telecommunications and data cables are twisted in pairs so that interference acts equally on both cores. This lay can be put to use: a signal fed in produces a pattern at the surface in the rhythm of the twist, and this pattern ends at the fault position. With an irregular lay length or with screened designs the method does not work.
Electromagnetic cable locating
A locating signal is applied to the isolated and de-energised line and traced at the surface. This produces the route line on which the measured distance is set out, together with a depth reading. The limitation: in densely occupied trenches the signal couples across to other services and the depth reading remains an approximate value, which is why the route is cross-checked several times.
Cable identification in trench and cable tray
In front of the house, power, telecoms and cable TV frequently share a trench, and the cables belong to different owners. Before anything is opened up, cable identification establishes from the signal and not from the appearance which cable is the one being sought, so that nobody ends up holding a third party’s cable or a live one. Its limitation: if several cables are of identical construction and in service, the network operator has to be involved.
What you receive
You receive a marking on the surface and a damage report as a PDF: it sets out in black and white what the distance was read from, and for the network operator or the property management it is the evidence that the ground had to be opened at this point.
Costs and effort
There is no flat rate: the cable construction, the length of the run, the number of taps and amplifier points, the accessibility of the ends, the type of fault and the surface above the route determine the effort involved. We agree the cost range with you by telephone before the job.
A fixed rule applies to the re-survey, and it is set out here deliberately: the re-survey is part of the scope of services. If our measurement was wrong, it is free of charge. If it was correct and the search at the marked position was simply not precise enough or the excavation not deep enough, the call-out is charged. The reason in one sentence: in the second case there is no measurement error on CFT’s part.
Whether an insurer covers the cost of the location work depends on the policy.
Frequently asked questions
We have excavated and found nothing. What happens now?
We carry out a re-survey. If our measurement was wrong, it costs nothing. If it was correct and the search at the marking was simply not precise enough or the excavation not deep enough, the call-out is charged, because in that case there is no measurement error on CFT’s part.
Do amplifiers, modem and end devices have to be disconnected?
Yes, measurement takes place on the free run, otherwise you measure the device and not the cable. We clarify in advance who disconnects them and who is allowed to open the sections.
Can you find the fault if nobody knows where the line runs?
Yes, that is the normal case: the route is recorded and marked using electromagnetic cable locating before the distance from the prelocation is set out along it.
The fault is only there when it rains. Can you still measure?
Faults that depend on moisture are typical of damaged cable sheaths and of damp plug connections and taps. If the fault is not present at the time of measurement, it is harder to capture – tell us when it last occurred.
How precise is the marking on the surface?
The aim is a marking at which the ground can be opened up at a single spot. How tight that turns out to be depends on the depth of cover, the ground conditions and the type of fault; the degree of narrowing down achieved is stated in the report.
Is the matter settled once it has been repaired?
Not quite. The line is cut for the repair, and afterwards there are two sections, both of which belong measured: a line that has once drawn moisture has rarely done so in only one place. Whether your electrician handles that in the same visit or we come out for it is a question of coordination – it should not be left open.
Contact and opening hours
CFT Group GmbH, Wiener Straße 99, A-2514 Traiskirchen, +43 (0) 2252 53169, Monday to Thursday 8:00–16:30, Friday 8:00–12:00. For Bavaria and Baden-Württemberg: CFT Group Deutschland GmbH, Lange Zeile 27, D-85435 Erding, +49 (0) 173 6842932. We deliberately stay within our own area: short journeys, site appointments at short notice and local knowledge of routes and network operators. Outside office hours, write to office@cft.at and we will come back to you on the next working day.
Related services
Service and supply cables
When the power supply cable is affected, from the service connection to the sub-distribution board.
Heating mats and heating cables
When the fault lies in the floor, wall or ramp construction.
Cable and pipe locating
When it first has to be established what is in the ground at all.
Describe what you are observing.
Just describe what you see – add a photo, and we can often settle on the right method before we even call back.
What happens next
- We read your message and match the case to a method.
- We come back to you – usually with a question that shortens the appointment.
- We confirm the appointment and what it costs before anyone sets off.
Rather talk?
+43 (0) 2252 53169
Mon–Thu 8:00–16:30 · Fri 8:00–12:00
Describe your case.
Fastest by telephone – then we settle straight away which method fits and what you should prepare.
Outside office hours, write to office@cft.at.