Cable faults
Cable fault location on control, coaxial and telecommunications cables in Austria and southern Germany
The gate stops, the doorbell stays silent, the camera at the entrance gives no picture. With multi-core control, coaxial and telecommunications cables it is often not possible to pull a new cable into the existing duct, and laying a new one would be the most expensive answer. CFT measures on buried multi-core cabling, identifies the cores, locates the fault position and marks it; the repair is carried out by your own technician. Describe the failure on +43 (0) 2252 53169 or in writing to office@cft.at, and we will clarify the cable type, access points and an appointment.
What we do on site
On the disconnected run we measure which core is affected and how far away the fault lies. Only with the route traced does that become a point, which we mark and photograph. You receive the damage report as a PDF and the reflectogram; we do not repair and we do not connect.
Key facts at a glance
| Methods | Time domain reflectometry (TDR), bridge measurement (Murray loop), twist method, electromagnetic cable locating, cable identification in trench and cable tray |
|---|---|
| Application range | Control and signal cables to gates, barriers, pumps and external installations, coaxial cables, telecommunications and data cables, multi-core cabling |
| Duration | Two hours at least, one further hour per complication. One or two faults are usually found in that time. |
| Result format | Damage report as a PDF |
| Service area | The whole of Austria as well as southern Germany (Bavaria and Baden-Württemberg) |
For you as a private customer
The failure shows itself as a malfunction, not as a power cut: the gate only travels in one direction, the intercom hisses, the television signal drops out in wet weather. Between house, gate, garage and garden shed there are often cables dating from the time of construction whose route nobody knows any more. We continue to work with the cable that is already there instead of digging a new route.
For you as a business
For telecommunications providers, IT companies, control engineers and industrial businesses the problem is not the failure but how long it lasts: an installation is out of service for as long as the fault position is unknown. With control cables there is also the identification of the cores at both ends – old terminal diagrams are seldom accurate and core colours repeat. We record which core is affected. Because this measuring equipment and the evaluation behind it justify the journey, we travel for it throughout Austria and to southern Germany – from Traiskirchen within Austria, from Erding into Bavaria and Baden-Württemberg.
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 also clarify which ends are accessible while the installation is running and who releases them.
2. Disconnection and initial measurement. Controllers and end devices come off the run, because only the free cable gives a clean measurement. Core by core we record which connection has failed and what type of fault is present.
3. Prelocation and line tracing. The measurement gives a length along the cable; where that length ends in the ground is shown only by the traced route. Junction boxes and duct bends are the typical places where faults are found.
4. Pinpointing and handover. The fault position is brought down to a point, marked at the surface and photographed. Handover is to your technician or the person responsible for the installation; CFT does not repair and does not connect up.
Equipment and methods
Time domain reflectometry (TDR) on coaxial cable
Coaxial cables have a defined characteristic impedance, and time domain reflectometry depends on it: every deviation – a crushed section, a damp plug connection, a torn screen – reflects part of the pulse, and the shape of the echo reveals the nature of the discontinuity. The limitation lies with long, heavily attenuated runs and with several discontinuities one after another.
Bridge measurement (Murray loop) on multi-core control cables
A control cable offers the most favourable starting point for bridge measurement: all the cores have the same cross-section and the same length, so the reference for comparison lies alongside within the same sheath. Comparing the faulty core with a sound one gives the ratio of the lengths up to the fault position. Both ends and a sufficiently low-resistance fault are needed; an undocumented junction box falsifies the length.
Twist method on twisted-pair telecommunications 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 and cable identification
For a distance to become a point that can be marked, the route has to be known: a locating signal is applied and the route is traced together with a depth reading. Control cables of the same design cannot be told apart from the outside; cable identification decides which cable may be cut on the basis of the signal, not of its appearance.
Choice of method on sensitive installations
Devices that react sensitively to voltage are connected to control and signal runs, so the initial findings determine the method. The choice of measuring method is agreed with the person responsible for your installation.
What you receive
At the end there is the marking above the route. With it you receive the damage report as a PDF: the fault pattern, the method used, the distance determined and the TDR trace as evidence of the measurement – all in one file. With this your technician can open up at the right place, terminate the cores and demonstrate that the system works, without laying a new cable.
Costs and effort
There is no flat rate, because the number of cores, the cable construction, the length of the run and accessibility determine the effort involved; we agree the cost range with you by telephone before the job. Insurance cover is not the normal case with control and signal cables.
If there is no fault at the marked position, we come out to re-survey. This is part of the scope of services. If our measurement was wrong, the re-survey is free of charge for you. If our measurement was correct and the search at the marking was simply not precise enough, or the wall, the chamber or the trench was not opened up far enough, we charge for the call-out, because in that case there is no measurement error on CFT’s part.
Frequently asked questions
Do controllers 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. Bring the terminal diagram along, even if it is old.
Can you establish which core is which?
The measurement establishes which core is affected; open-circuit cores are among the types of fault we locate. Whether the full identification of both ends is part of the scope beyond that is clarified before the appointment – on older installations this is frequently the actual job, and then a subject in its own right.
The fault only occurs occasionally. Is a measurement worthwhile?
Yes. Intermittent faults usually have a physical cause – a damp junction box, a crushed spot – and such places often show up in the TDR trace even when the fault is not present at that moment.
What happens if no fault can be found at the marked position?
Then we carry out a re-survey; the re-survey is part of the scope of services. If the fault lay with our measurement, the re-survey is free of charge for you. If the measurement was correct and the search at the marking was simply not precise enough or it was not opened up far enough, we charge for the call-out, because in that case there is no measurement error on CFT’s part.
Does location also work with cables inside the building?
The measurement is independent of where the cable lies. What is limited is converting the distance into a place, because risers and reinforcement make line tracing more difficult; we then narrow the position down to a section between two known points.
What still has to be measured after the repair?
Both sections. If the run is cut for the repair, two sections are created, and each of them can carry a further fault position. On control and signal runs that only becomes apparent in operation, when the installation is running again and reports intermittently. The check measurement is carried out by your electrical contractor or by us.
Contact and opening hours
For jobs throughout Austria: CFT Group GmbH, Wiener Straße 99, A-2514 Traiskirchen, +43 (0) 2252 53169. For jobs in southern Germany: CFT Group Deutschland GmbH, Lange Zeile 27, D-85435 Erding, +49 (0) 173 6842932. Monday to Thursday 8:00–16:30, Friday 8:00–12:00. Outside office hours, write to office@cft.at and we will come back to you on the next working day.
Describe the findings.
The more precisely you describe the findings, the more directly we can go to work. Plans, readings and photos help us settle the method in advance.
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.