Cable Locating

What is cable locating?

Cable locating is the process of determining the location of an underground cables using geophysical detection methods such as electromagnetic tracing or Ground Penetrating Radar (GPR) prior to a digging activity such as mechanical excavation and drilling or designing and planning for these types of excavation works.

The most common way to locate an underground or embedded cable, whether it be an electricity cable, Telstra copper, RMS traffic cables or signals cable on the on railway would be to use electromagnetic induction principles.

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Locating underground cables uses electromagnetic energy to transmit a current and frequency down the coper or other metallic wiring causing it to emit a detectable magnetic field.

Once the target cable or service line is induced with the electromagnetic field, it is then possible to trace and find its location by matching the frequency of the electromagnetic field on our receiver and walking in strategic sweeping grids to pin point the location. This will give us the highest peak reading and current measurement indicating the cable location below.

Cables are used in many ways to provide data and communication transmission as well as supplying electricity used to power homes and businesses worldwide.

They can power heavy industrial machinery down to RMS traffic lights on Sydney roads.

Cables can be found underground, inside walls and ceilings as well as overhead and submarine.

Because cables can be found in what may seem some of the strangest locations, depths and heights, it is recommended to have them found before undertaking any works that may potentially damage them.

Cables, especially underground cables and cabling inside concrete slabs and walls can come in shapes big and small. Some are more dangerous than others to workers and equipment, but both have their fair share of hazards if disrupted.

That’s where we come in. Sydney’s professional and certified underground cable locating company.

Why choose Geoscope to locate your underground cables

We provide underground location solutions to industry professionals helping them be more efficient and confident when undertaking their on-site project using mechanical excavators or drilling machines.

By having the accurate subsurface utility information from the beginning of a project, our clients are better situated to succeed in completing their work on time and on budget by minimising the risks involved with working around buried pipes and cables.

When choosing the right cable locator for you, it makes sense to pick one with the appropriate credentials and experience to complete the required task. One that is friendly and can give you the right advice and information on the location.

By having the accurate subsurface utility information from the beginning of a project, our clients are better situated to succeed in completing their work on time and on budget by minimising the risks involved with working around buried pipes and cables.

When choosing the right cable locator for you, it makes sense to pick one with the appropriate credentials and experience to complete the required task. One that is friendly and can give you the right advice and information on the location.

You can rest assured Geoscope have the cable locating industry standard qualification in the DBYD Certification and the experience to find the traceable underground services at your site.

How to accurately locate underground cables

Electromagnetic cable location can only be so accurate. Afterall, we are locating a field that is generated around the cable and not the actual cable itself.

This is a common misconception that when we locate out on site, we are finding the actual cable but the signal we are tracing is the actual EM field. Because this electromagnetic field can be distorted by outside factors, we should treat this signal only as an indication of the cable location and depth.

Radiodetection list the accuracy of the cable locator as plus or minus 2.5%. It should be noted that this is in ideal soil conditions and areas of minimal to zero electrical disturbance.

Depth accuracy Line: ± 2.5% tolerance 0.1m (4") to
3m (10ft)
Sonde: ± 2.5% tolerance 0.1m (4") to
7m (23ft)

The Australian Standards for utility locating classify the tolerance of electromagnetic trace locating listed as a Quality Level – B (QL-B) as having a depth range of plus or minus 500mm and a location range of plus or minus 300mm.

As you can see, there is quite a large accuracy buffer set out. If you are planning to excavate out an area you need to know where the cables are accurately located.

This is where potholing and non-destructive excavation process comes in. By seeing the underground cable with your own eyes, you can physically measure down and get the most accurate depth any other method or machine can give you.

Potholing works hand in hand with electronic cable locations. To pothole or non-destructive dig, you need to first have an idea where the cables are.

If you think you can just start sucking up the earth with a vac truck and uncover the cables, you can be in for a long day of expensive non-destructive vacuum excavation.

Sydney metro cable detection solutions

Geoscope Utility Detection Services Pty Ltd travel Sydney wide locating underground cables covering the metro. In some cases, we also travel to other areas of NSW if clients wish to have our expertise in those parts of the country.

Being based in Sydney and working at some of the most congested places for underground cables in the country sets us up as being ready for any task possible.

Whether it’s locating Telstra cables in Parramatta, Ausgrid cables in Bondi or fibre optic cables in Haymarket, or complete pipe and cable locating, rest assured Geoscope are well equipped for the job.

With the construction of major infrastructure and tunnelling projects being completed, much of our work is in the heart of Sydney.

Although, Sydney’s West and South West has seen enormous populations increase lately which also means upgrading infrastructure and rail works which has led to busy periods of cable locating in these areas.

What are some examples of the type of underground cables we locate?

Underground cables come in all types of sizes and various functionality. Here are some examples of cables underground that we can locate:
  • High Voltage transmission cables
  • Low voltage electricity cables
  • Street lighting electrical cables
  • Roads and maritime traffic signals
  • Electrical distribution cables
  • Mains and sub-main cables
  • Earth and ground wires
  • Communication cables
  • Fibre optic cables
  • NBN Cables
  • Copper cables
  • Irrigation control solenoid cables

What are the dangers when digging around underground electricity cables?

Let’s not beat around the bush when it comes to personal safety and potential disruption to critical cables and underground services.

The fact is, death and serious injury is a real threat when it comes to contacting live electricity cables.

Digging around electricity cables should not be taken lightly. Even if you scratch the insulation layer off to reveal the live conductor, there is a risk of contact which can serious from up to thousands of volts is something no worker should be exposed to.

Can fibre optic cables be found with our cable detection tools?

We can locate fibre optic cables with our electromagnetic and GPR locating methods, but this depends on a few factors. As these cables are non-metallic, we can use a few different techniques to locate them Here is a list of what we can do to locate fibre optic cables.
  • Locate a copper cable located inside the same duct or conduit as a fibre optic cable
  • Feed a traceable rodder through a duct or conduit which an active electromagnetic signal can be located.
  • Direct connect to a trace wire which has been laid in the fibre optic cable trench or pulled through the duct or conduit.
  • Use Ground Penetrating Radar – GPR to locate a trench or disturbance where a fibre optic cable has been dug through. Ideally this location will be confirmed by potholing.
  • Locating buried transponder at intervals on a direct buried fibre optic line
  • Pothole and slit trenching

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What is the best way to locate underground cables?

The best way to locate cables is to use a form electromagnetic field induction locating method.

The ideal way to induce a signal into a cable would be to use the direct connection leads, although this has its complications when coming into contact with live electrical conductors. It’s for this reason we use the coupling ring clamp to surround the cable and induce a signal into the line that way.

This method is preferred as we don’t need to touch or expose the wiring underneath the insulation and do not have to compromise safety to complete our works and 99% of the time there is minimal distortion on the trace signal. If we do have a poor signal, there are other techniques out there such as transmitter position and frequency and gain selection we can employ.

Electrical cables and conduit

Electrical cables can be found underground in conduit as a well as being direct lay or buried. Direct buried electrical cables will usually have some form or warning tape over them while depending on the voltage of the cables they will have a hard-mechanical protection poly cover.

Electrical cables can be connected from pit to pit by conduit but often times there can be sections where the cables have open points where they are direct buried for joint bays. Care should be taken when excavating in these areas as the

Electrical conduits used underground can vary in size from being 20-30mm inside diameter to 250mm. The smaller diameter conduit is used for low voltages while larger diameter conduit needs to cater to larger high voltage cables.

Direct buried Telstra cables

For ease and speed of installation, Telstra cables were at times buried directly in the ground with no conduit.

These direct cables are indicated on the Telstra DBYD as a straight line with a short perpendicular dash coming off it. This detail should be checked on the plans at the planning and locating stage of the project. This will help identify this cable any extra lines that may be present inside Telstra pits.

If you need help identifying any information on Telstra plans including direct buried cables, feel free to contact us and we’ll do our best to help you out.

Warning and marking tape for underground services

Underground marking tape is laid above a service at the time of installation to provide a warning to those excavating and digging that directly below are buried pipes and cables.

This has saved many a contractor from a potential service strike. Especially when the service wasn’t originally identified before the excavation process because it wasn’t on a plan or made of traceable metallic materials or one reason or another.

As the warning marker tape is a few 100mm above the service, the machine operator and spotter will see the coloured tape and proceed with caution.

In some cases of non-metallic underground services such as fibre optic cables and pvc water pipes, the installing contractor may install a conductive tracer tape.

This warning tape has a built-in wire that can be direct connected to with a transmitter and located just like any other metallic pipe or cable.

Unfortunately, this safety measure is not always covering every underground service due to varying methods and requirements of service installation.

Services that have been Horizontal Directional drilled or bored through earth and rock usually do not require warning tape due to the pulling method and the cover between the service and the tape if it survived would be negligent in terms of contact to the underground service.

Why are Geoscope the best choice in the Sydney area for underground cable locating?

Geoscope are underground cable locators, specialising in precise detection of underground cables in Sydney and the surrounding areas.

We work with professionals in the construction and building industry helping them to speed up their workflow by knowing what cables are underground before they make run into them accidently.

We use world leading cable detection equipment and techniques to accurately identify the position and depths of any underground services beneath your site.

Using both electromagnetic and Ground Penetrating Radar methods, Geoscope are able to quickly and accurately identify underground utilities. We subscribe to the Australian Standard – AS 5488-2013 Classification of Subsurface Utility Information – SUI, and are certified DBYD locators, so our clients have peace of mind.

Working with us to locate underground services will not only reduce unexpected delays from possible damages but also reduces design and construction costs.

If you’ve got excavation, cutting or drilling works in the pipeline, contact Geoscope. Our highly-skilled technicians are experienced in subsurface utility engineering processes all across the city. Start your project on the right track with Sydney’s Cable Locating Specialist – Geoscope.

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