In previous articles, I explored what makes a utility locate not just good but meaningful and accurate - a true recipe for success. Like any good recipe, a successful locate includes key ingredients:
Skip one of these steps, and you might still end up with a result—but much like a recipe missing a key ingredient, the final outcome could leave you with a bitter taste.
We continued with the question of, “Are you well grounded?” In that article, a fair amount of time was spent on understanding the best practices centered on the proper grounding of a utility, combined with the placement of the grounding rod, and factoring in the electromagnetic field distortions in the soil.
So, we have the recipe, and we get that grounding is important, but is that it? Not quite, now we need to talk about frequency.
Grounding + Frequency = Accuracy
The frequency is transmitted onto the utility and is always seeking a return path through the soil. A factor influencing the success and accuracy of the locate, and one that can be easily overlooked, is the soil’s conductivity. The amount of moisture or the lack of the existence of the types of soil ranging from sandy to clay and all in between can have a profound impact on the frequency (signal).
No matter the type of locate set one uses in the field to identify the targeted utility, all operate on the same basic principle that has remained the same for decades. The electromagnetic field is generated by the locate set’s transmitter emitting a (pre-selected) frequency on the intended target utility (Active Locating). Think of the electromagnetic field as a wave, with high points (Peaks) and low points (Nulls). When a locate technician follows these waves, they aren’t finding the utility itself - they’re reading the invisible signal it radiates. It is the Peak and Null of each frequency used that aids the locate technician in pinpointing the targeted utility. The highly trained locate technician can determine the utility’s location by accurately determining the Peak (the most accurate) signal strength location.
The next step in the evolution of locating is the choice of what frequency I should use and why. The skilled locate technician has a strong understanding of locate theory and the locate set used daily. Choosing the right frequency is both an art and a science. Frequencies are typically categorized into three bands:
Always start with the lowest frequency that will get the job done. Lower frequencies reduce leakage and prevent signal bleed, leading to more accurate locates and fewer utility strikes.
A successful locate isn't just about the tools—it's about the technician’s judgment, the conditions on-site, and choosing the right frequency for the job. Take the time to assess, ground properly, and adjust your settings. Because when safety, accuracy, and knowledge work together, you don’t just find utilities—you avoid disasters.