If you know anything about the utility industry, you’ll know that undertaking any excavation will inevitably bring site workers into close proximity to underground utilities, including electricity, gas, water and telecommunication works.

Increased consideration and scrutiny is now paid towards knowing the exact location of all buried utilities before and during the excavation process. And rightly so. Not knowing where buried cables are located can lead to serious consequences to worker health, as well as costly disruptions to services and construction progress.

To protect against utility strikes, a cable locator is used for cable avoidance to map the presence and proximity of any buried utilities that could prove troublesome. Here are a few notes based on our years of experience at Sygma Solutions on how this process works.

Major Types of Detection

There are two main types of detection when it comes to cable avoidance, which are:

• Passive location – Used to locate an electromagnetic field that is already present
• Active location – Adds a specific signal using a signal transmitter onto a utility in order to reveal its location

The Passive Location Method

Some signals are already discoverable. All you need is the right equipment to detect them. Buried utilities may give off certain signals radiating from power cables which can be picked up with the right industry equipment.

This method involves looking for unknown lines by detecting an electromagnetic field with the help of a detector or receiver. This can be useful in certain areas, but it does not allow us to distinguish between the type of lines that are buried, which might be necessary information when performing excavation work.

Some underground cables are already energized and can be located by simply scanning for their electromagnetic fields. However, underground utilities or cables that are non-energized may be located by scanning re-radiation of signals that are induced by a radio transmitter.

Active Location

Most buried utilities can be missed when only detecting in passive modes. And this can be a leading cause of cable strikes as operatives perform excavations unaware of buried utilities in their vicinity. A basic sweep of an area might offer some information about what lies below, but this does not guarantee that it is safe to excavate.

The active detection method involves locating a specific line/cable by means of injecting a specific frequency signal using a transmitter and then tracing it with a receiver. Despite not carrying any live signals, you can still discover their location by inducing a signal directly onto the utility.

This frequency or electrical current will enable the cable to be identified with the locator, which when used alone, would not reveal the information needed to guarantee safety.

There are a number of industry tools and equipment that can help with both the transmitting of signals and receiving of them. Using the best quality products can also help to significantly improve the detection process, but success also relies on the appropriate knowledge, training and experience of individual operatives.

How Do Cable Locators Work?

A cable locator, as it is termed in the industry, generally consists of two components. The first is a transmitter and the second a receiver. A transmitter is simply some kind of AC generator that can create a signal or current which is passed to underground utilities. This signal can be set to specific frequencies to make it easier to trace. An electromagnetic field of the same frequency is created around the cable which can then be detected by the receiver.

The receiver is the part that does this tracing, and picks up any important signals and tells you where cables are located. Above ground, the electromagnetic field can be detected. You can also use a receiver on its own without a transmitter to pick up on signals from already energized utilities.

Learn More About Cable Detection

If you want to learn more about how cable detection works; would like to discover the tools and equipment available for the sector; or would like to inquire about a professional training course to start your career in cable avoidance, get in touch with us at Sygma Solutions. We have a wealth of industry knowledge and programs that could support your needs.