Passive vs. Active Utility Locating: What’s The Difference?

When you’re beginning a new project, utility location should be at the top of your list of tasks to make sure that everything goes smoothly, without jeopardizing the structure of your existing utility grid. But what if you’re not sure where all the utility lines are, or 811 services just won’t provide the level of detail you need to complete everything safely? Active and passive utility locating services make all the difference between a successful project and one where you spend too much time guessing. Check out this infographic on some key differences between active and passive utility locating, and continue reading to learn more about what we can offer you, including water line locator services in Manhattan, NY, and the surrounding areas.

Active Utility Locating

Active utility locating works best when you need to locate a specific utility that has an unbroken metallic connection from one end to the other. An electromagnetic frequency is sent to the pipe or line on one end and transmitted down its length. This process allows a surface receiver to pick up on the signal and trace it across the surface of the ground, whether it be soil or concrete. Electromagnetic (EM) location uses a transponder to transmit a low-voltage alternating-current frequency in a conductive probe or by attaching directly to the utility line. This method creates an EM field around your property’s utility lines and can be detected by a receiver, allowing a professional to map the line for later reference.

Passive Utility Locating

While active utility locating provides accuracy and specific information about each of the utility lines on a property, there are certain situations where it won’t work. In the event of a broken pipe or line, the frequency won’t be able to transmit across the entire length, making it difficult — if not impossible — to trace fully. Plastic or concrete pipes that don’t conduct frequencies are another area where active utility locating won’t work well. In these cases, using a passive location technology is a better alternative.

Ground Penetrating Radar

One example of passive locating is ground penetrating radar. This method allows you to get a full map of the surface under your soil, including utilities and other features that you may not be aware of, such as voids, old wells, or graves.

EM Location

Passive location uses sensitive equipment to detect EM signals that the line already produces. A transponder isn’t necessary to detect the line, but it will need to be an active electrical power or communications line. If the line doesn’t carry a signal, this method of location will not work.

GPR One Call Utility Locating Services

At GPR OneCall, we offer a wide range of services available to help you with utility locating for your next project. If you require an underground utility survey near Philadelphia, PA, New Jersey, or New York City, contact us today!