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How Does a Utility Locator Work?

Blog how does a utility locator work As the vast network of lines running underground continues to increase, locating them has become more of a challenge. And because the ground has become so congested with utility lines, it’s important to know where they are before you start digging. This will ensure the safety of not just yourself but everyone around you. The first step is to call your state’s one-call office and give them the location of the area you want to excavate. Then, a contractor will mark the location of all of the utility lines running underground. However, the markings may not be as accurate as you need them to be. And sometimes, privately owned lines that the contractor isn’t aware of may not be marked. Many contractors start excavating without double-checking each marking, which is fine if they're accurate. But if one of them is slightly off, you may not know if a line is running through that area. You can either keep going or have the one-call contractor come out again. Either way, it will cost you both time and money. But if you have a utility locator, you'll be able to confirm each marking so you can find any underground facilities that might have been missed.

How a Utility Locator Can Find Underground Lines

Blog how does a utility locator work

Finding an underground utility line is similar to tuning into a radio station. Each one transmits a different signal, and an underground utility locator is meant to pick up signals that run through these lines. Many of them give off some type of electrical charge or radio signal. And like a radio station, most of them will have their own distinct charge or signal. However, some lines don’t give off a charge or transmit a radio signal of any kind. And in these situations, a transmitter can be used to run a signal through a metal line (which the pipe locator can pick up).

Types of Underground Location Methods

A utility locator can use one of the following methods:
  • Active Locating — This method looks for a specific utility line through the use of a direct connection or an inductive method. A specific frequency is directed through the line from an above-ground facility (such a gas or electrical meter).
  • Passive Locating — This method is often used by contractors who want to check the location of unknown lines. They will sweep the area with the receiver, so they can find a utility line that's sending off a signal. However, the contractor won’t be able to determine what type of line is running through the area.


Because utility lines and pipes can be made of different materials, a higher or lower frequency may be needed to find them. This is how an underground utility locator that can tune to different frequencies may be an advantage. Many of these multi-frequency systems can tune up to five different signals. If you’re looking for a pipe locator or any other underground location device, feel free to look at what we have at Engineering Supply. We’re sure you’ll be able to find a product that will meet your specific needs.
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