Locating Telstra Cables

Plan your activity. Work out were you will be cutting or digging and work out if you have underground Telstra cables nearby. If you’re not sure, you can always engage a Certified Locator to come out to site and investigate with electromagnetic cable locating methods. 

There are a few methods and processes to locating underground Telstra cables although the best way to locate these cables is by using electromagnetic locating devices. Depending on the Telstra cables construction and make up, further equipment may be necessary, but we’ll start with the basics. 

The Telstra network typically consists of copper and fibre optic cables.  

Copper Telstra cables can be fairly straight forward to find underground with EM locating as they are a metallic service which can carry a conductive signal. 

Copper cables can be traced by inducing a current through the cable via a ring clamp and a transmitter which produces an electromagnetic field that can be picked up by a receiver.  

Once induced with the current, the target cable location can be traced and marked quite accurately to a QL-B quality level. 

Telstra fibre optic cables offer up some challenges when it comes to locating their underground position as they are largely constructed of non-metallic materials, which means they cannot be induced with a transmitter. 

Although we cannot connect up an induction ring clamp or direct connect to these non-metallic fibre optic cables directly to locate them, we can use similar methods to get around the issue of the actual service being non-conductive. Some steps we can take to locate the underground fibre cable location include: 

• Clamping and locating a copper cable inside the same duct/conduit as the target fibre optic cable. 
• Direct connecting and locating a trace wire that is either inside the conduit or laid inside the trench of the fibre optic cable. 
• Feeding a traceable rodder through the length duct or conduit and inducing a current through the rodder 
• Locating buried fibre optic marker ball transponders 

Locating Telstra fibre with copper cables in the same duct or conduit. 

Just to recap, the method to locate these copper cables is to apply a current into the cable through the ring coupling or clamp to produce a traceable electromagnetic field which can be detected by a locator technician following the highest readings. 

This is by far the easiest method to locate Telstra fibre as it eliminates the need to break out the extra rodding gear or dealing with possible broken trace wires. 

Locating a fibre optic cable trace wire 

On the odd occasion, and I’m talking rare, a traceable trace wire is able to be located which has been laid in the fibre optic trench. 

Trace wires found in communication assets can be found:  

• Inside a conduit or duct along side the target fibre optic cable  
• Above, below or to the side of a conduit/cable in the trench backfill 
• In warning tape that incorporates the wiring inside the tape which usually sits anywhere from directly on top of the asset to a couple of 100mm above the service. 

If available to connect onto, trace wires can be tied or wrapped around brackets or fixtures towards the pit opening. They can be floating in or around the bottom of the comms pit or found at the opening of the conduit. It pays to double check if the wire is present as it they are intact, it can be quite the time saver. 

Much like tracing a metallic pipe, we can direct connect our red and black leads to the wire and earth stake to complete a circuit to produce a traceable magnetic field. 

Once we’re connected up to the trace wire, we can mark out the fibre cable (trace wire) location using the peak and null setting on the receiver. 

Locating a fibre optic cable, inside a conduit with no trace wire or metallic cables inside.  

When there’s no metallic lines to trace inside a fibre optic cable duct, we need to get creative to be able to locate the fibre cables position. We do this by pushing a metallic line inside the conduit that can be traced, often known as a duct rodder. 

This duct rodder is made of a fibreglass construction with a thin metal wire core which is the traceable element. It is produced in various diameters to suit the rigidity of the application and the size of the conduit needing to rodded. I find it’s easier to carrier a few different traceable rodder sizes in our work vans so we can be prepared for different situations out in the field whether it be rodding smaller 30-100mm conduits all the way up to 300mm storm drains and in cases even larger. 

Once the rodder is all the way through the conduit, we can use the direct connection procedure to transmit a signal down the rodder which will produce an electromagnetic field. 

One we have an electromagnetic field that is being transmitted, we can locate this position to the best point possible given the situation, short of verifying by potholing. 

Locating buried transponders

Buried Telstra transponders or marker balls as Radiodetection call them are little transmitters that are excited or energised once a special type of cable locator receiver has pasted directly over it which gives off a signal at a set frequency typical to the type of asset.  

The main difference with this special type of locator compared to a normal pipe and cable locator is that it has a flip down antenna to locate the electronic marker ball. Other than that, once the extra antenna is folded away, it can be used to locate other metallic services using passive and active frequencies. 

Often times the transponders are indicative of a change of direction between certain points or at a ‘tee’ intersection of a service. This is would be indicated on the Telstra plan as a letter T or TR inside a circle. 

When the rough location of the transponder has been established by referencing the plans and the Telstra assets on site, we can lay out a mental grid and sweep the site till we receive a reading with the marker ball locator.  

Once the transponder locations have been marked, we can align the points and proceed to pothole and visually confirm the optic lines. 

To be truthfully honest, being a Sydney based locator, buried transponders are not really used in town. I have personally only come across 2 sites in my time being a DBYD certified locator which had a buried transponder. The first location was in Lithgow, near the Zig Zag rail way line and the 2nd was towards Bathurst area. 

As you can see above from the only 2 examples of where I located buried transponders, they are usually found in areas outside of the Sydney metropolitan locations areas and mainly in places of large stretches cable runs. They could also be installed in areas of rough terrain where direct buried fibre runs were the most cost-effective installation method vs the actual cable protection. 

 Because the cable has been backfilled with no conduit or wire, we are unable to complete the procedures above using the traceable flexi-rodder or direct connection method onto a trace wire. The equipment we need to use to locate the transponder is a electromagnetic receiver that has a built in.

Multi conduit duct banks 

It’s not unusual, and quite the norm in built up city and metro areas like Sydney, Parramatta, Blacktown, Rockdale and Liverpool that Telstra have multi conduit duct runs from pit to pit running underneath the footpath and roads we walk and drive on in everyday life. 

You will find the closer you are to a Telstra Exchange building, the larger the pair cables and more major fibre cables will be. This means that more conduits are needed to carry the cables through the underground network out to the customers. 

Many times, on site we’ve come across duct banks which have included 24, 36 and 56 sets or more of P100 conduits running down the main streets of the CBD and even across train stations railway tracks. 

The challenge with locating these large banks for Telstra cables and conduits are: 

• Manhole depth and access to conduits 
• Often are classed as special work location – SWL by Telstra 
• Confined space entry 
• Extra personnel 
• Pedestrian management control 
• Time taken to confirm each bank pit to pit 
• Locating only the traceable copper lines vs rodding the fibres as well 
• Hazardous substances located within the Telstra pit  

With large Telstra conduit banks comes large manholes. 

Special Work Locations (SWL) are often marked on the Telstra DBYD plans in areas were some of the above challenges have been identified. It could be manholes that are deeper than 2 metres or have non-Telstra assets running through the chambers such as gas mains and water mains.  

Either way, special care has to be taken and this is what needs to be factored in when working on the large projects in town. Safety is paramount and no cable location job is worth risking a life for. 

What someone needs to locate Telstra cables? 

Here’s a small list of what someone may need to locate Telstra cables. 

• Telstra Accredited Plant Locator – TAPL
• DBYD Certification 
• Calibrated locating equipment. Radiodetection, viavax, Rycom or rigid etc 
• Current Dial Before You Dig Plans  
• Telstra pit barriers and guards  
• Gas detector 
• Pit lid lifter 
• Pit lid seal breaker 
• Marking paint 
• First aid kit 

Before you rip open a Telstra lid cover, a requirement to access the network is to be Telstra accredited.  

To get your Telstra accreditation, you will need to have firstly completed your DBYD Certification. The process to complete your DBYD certification is all on the website. 

By having your DBYD Certification, you would have displayed the skills and knowledge to locate not only the Telstra network safely and by the book, but all types of underground services using electromagnetic locating and marking to the Australian Standard – the Classification of Subsurface Utility Information. 

Then comes the actual piece of equipment that will locate the Telstra cables. You will need an electromagnetic locating device. We only use Radiodetection equipment that has multi frequencies built in. The advantage of having multiple frequencies to select from are the choice of lowering the frequency in congested areas with many underground services or raise the frequency higher to induce a signal in areas of blind searching. 

There are risks involved when working on the Telstra network which may seem like common sense but the problem with common sense is that it isn’t all that common.  

Things like barricading the open man hole safely with a set of barricades so pedestrians don’t fall in or testing the manhole for gaseous substances. Its all about safety. 

If you’re after further information on what you need to locate Telstra cables, feel free to contact Geoscope via email.