NULCA was formed in 2004 with the mission “to define, establish and maintain best work practices performed by the underground utility locating industry. To establish work standard and competencies which will assist in providing a safer work environment for the general public, excavators, and all people in the civil works and underground service locating industry.”

In a membership survey the same year, training and accreditation was ranked as the most important strategic objective. Running a close second was the development of standards as a benchmark on which competence and accreditation are based.

NULCA saw the first step as developing a set of standards that would form the basis from which competency based training would be built. JB Hunter Technology, a Newcastle based national registered training organisation, was requested to develop a course based on the use of electronic utility equipment.

JB Hunter is one of the major telecommunications training organisations in Australia, and is well known for the national presentation of the current Accredited Telstra Cable Location course.

Electronic location

Today, electronic locators are the worldwide standard for locating buried pipes and cables. A number of specialised manufacturers offer a choice of locators ranging from simple equipment to detect the presence of buried cables to the sophisticated instruments for pinpointing, identifying and fault finding buried pipes and cables in the most complex situations.

To locate cables effectively the operator must know their equipment, as well as use their intuition and good judgement. Certain techniques can alert the operator to potential problems and make the difference between a good locate and a bad one.

When using electronic location the flow of an alternating current generates an alternating magnetic field that can be detected with what is basically a radio receiver. If the receiver is tuned to the frequency of the alternating current signal, the operator will get a response that increases in strength the closer the field becomes. By finding the peak signal, the operator can find the position of the cable or pipe.

It is important to remember that the operator is locating a frequency specified electromagnetic field that emanates from the cable or pipe that is being searched for.

If the end view of a buried cable with a locate signal applied to it is looked at, in a non-congested area, an electromagnetic field emanating around it in a circular shape would be seen. The field is strongest where it is closest to the cable.

In the NULCA training course, the basics of locating buried cable or pipe using a transmitter to apply a signal to the conductor is discussed, as well as tracing the conductor’s path using a receiver.

Other utilities create other paths for current travel. Currents always take the path of least resistance particularly in a congested area. For example, if a current has the choice of travelling 650 m through earth or travel 30 m over to an adjacent copper wire and 630 m down the copper, it becomes clear how a signal on the wrong utility can be obtained.

Although congestion cannot be reduced, the frequency of choices, transmitter location and ground stake positions can reduce the conflicting signals.

It has to be metal

Electronic location relies on a continuous metallic object that can carry the signal to be detected.

Optical fibre cables typically do not contain any conductive or metallic elements that can carry a direct or induced trace signal.

In addition, empty PVC or earthen ware conduits cannot be located electronically. The introduction into empty conduits, of a self powered Sonde (a battery operated device that emits a specific signal), or a conductive metallic snake for direct signal connection, may assist in the accurate location of the non-metallic underground asset.

Although the electronic locator can be invaluable is avoiding damage to services, the operator should always avoid assuming too much from the readings given by the machine.

NULCA says that it is important to always perform a ‘sanity’ check. For example, always trace a pipe or cable to the next pit or access point to ensure that the right conduit is being traced.

In many cases it is essential that the cable be exposed by careful hand excavation to confirm the electronic location that the operator has found.

The Utility Asset Location course

The three day course provides a detailed introduction to electronic locating principles, with a focus on:

* transmitter and receiver operation * applied signal frequencies, signal injection and grounding * effects of different soil conditions * blind searches and tracing techniques

A detailed workbook identifies location problems and solutions to correctly identify the target pipe, line or cable.

The second day of the Underground Asset Location course is an extensive training component that addresses the industry obligations in regard to cable location practices and procedures. An understanding of and compliance with current occupational health and safety legislation and adherence to acceptable NULCA industry guidelines is required to ensure common national work standards.

Day three has a Telstra focus, which will include an extensive introduction to Telstra plan and drawing interpretation combined with the access requirements for the Telstra network. The Telstra theory will be followed by a practical in-the-field use of location instruments.

The third day will also provide the first of a number of utility location endorsements.

All course attendees will receive a certificate indicating their successful completion of the NULCA recognised industry training program and completion of the Telstra accredited cable locator course.