Active vs. Passive Utility Locating: Which is Better?

Underground service location is always an important pre-work measure for any excavation project. That said, locators need to have in-depth knowledge & extensive experience in the industry to perform their job as accurately as possible. Speaking of knowledge, they must be more than familiar with the different methods involved (active & passive locating). Moreover, they should know which solutions should be used based on the project requirements, from direct connection to ground penetrating radar.

Sydney locating companies with sound knowledge on these like Geosurv ensure clients that they are in expert hands. On that, which is exactly the better locating method? Active or passive?

Active Locating

In this method, Our locators use a transmitter & a receiver to search for a utility line. The transmitter introduces an electromagnetic frequency (EMF) to the line down its length. The receiver then picks up the signal. The signal allows tracing the linear depth & direction of the utility on the surface. Afterwards, locators put markings on the ground based on the readings. This method provides the highest accuracy as it can distinguish between different utilities.

Active service locating can be done either through a direct connection (conductive) or an inductive method.

  • Conductive Locating – This involves directly attaching the transmitter to the utility line which creates an electromagnetic field on the outside.

  • Inductive Locating – This introduces the EMF to the line by positioning the transmitter directly over it above ground. Aus locators use the inductive method when a direct connection is not possible.

Some of the equipment used in Active Locating are inductive clamp & split-box locator.


This method is highly effective if you need to locate a metallic or conductive utility line that has a clear connection from one end to another. Also, this is suitable when a tracing wire or cathodic protection is present. This location method is a must for rail services.

Passive Locating

Passive locating involves identifying the location of an underground utility by detecting the radio transmissions or frequencies that are already present in it. Here, locators look for electromagnetic signals being reemitted by the utilities. However, passive locating cannot differentiate between service lines as active locating can.


If utilities are broken & frequencies cannot be fully transmitted, locators use this method. Non-conductive pipes or lines also require passive locating. A popular passive locating service is the ground penetrating radar, Sydney locators usually conduct passive locating at the beginning of a project when access points are unknown. They also do this at the end to make sure no utilities were missed.

Final Thoughts

In summary, deciding which is better between active & passive locating depends on the needs of a project. Each method has its pros & cons. Moreover, a single project may require conducting both methods depending on the location of different utilities. Example: Locators can use an inductive clamp along with a ground penetrating radar. Sydney clients who need experts to do underground utility locating can rely on Geosurv. With our extensive experience & use of high-quality equipment, we know best how to conduct the job. To get a quote, call us today at 1300 554 675 or send us an email via