Arguably the most important part of any underground excavation job is always the same: accurately locating the utility lines. While there are other pre-work measures, work cannot begin on the jobsite until all utilities are identified.

While locating remains an important safety precaution for contractors, technological advancements have made the process both quicker and easier in recent years. Contractors should always start the locating process by contacting their local 811 or One Call office. Additionally, underground utility locating equipment can quickly and accurately help verify marked and unmarked utilities before work can begin.

Here’s what you need to know before purchasing and using a locator:

Active vs. passive locating
There are essentially two locating methods — active and passive.

Active locating involves searching for a specific line using either the direct connection or inductive method. Each line gives off a signal, so the locator is either attached directly to the line or, if the operator cannot make a direct connection to the line, a frequency is selected and induced into the ground which attaches itself to the utility.

Passive locating is a method used by contractors to check the area for unknown lines. This method detects any frequencies created by energized conductors and radio signals being radiated by utilities. However, this method does not allow the operator to distinguish between the types of lines. Passive locating is often used in two ways: at the beginning of a project to scan the jobsite for utilities where access points are unknown and as a final step after utilities are located to ensure no utilities were missed.

Single vs. multiple frequency units
One way to categorize electromagnetic locators is to break them down into single and multiple frequency units.

Single-frequency systems work well on lines and pipes in areas where the underground is not congested. This is because in congested areas the high frequency may produce a distorted signal making it difficult to distinguish one utility from another. The other limitation is that most single-frequency locators cannot determine the depth of the line.

Depending on the type of locate, different frequencies are going to be more beneficial than others. Multiple frequency locators allow the operator to adjust the frequency to the type of line they are trying to locate. Locating at a lower frequency reduces the chance the receiver will pick up a signal from a nearby line, allowing for a more accurate locate of the correct line. Multiple frequency locators are ideal for crowded underground conditions.

Current measurement index and depth estimator
Locators that offer current measurement index (CMI) help distinguish the target utility from adjacent signals, allowing operators to focus on the target line and help eliminate signal bleed over from other utilities. This along with a depth estimation feature allows contractors to achieve the most accurate locate of a utility before bringing in a vacuum excavator to perform a visible locate on the line.

Before purchasing a unit

While it’s important to select a utility locator that features the cutting-edge technology, the unit should also be durable enough to handle the jobsite conditions.

Durability is key because contractors take equipment in and out of a truck on a daily basis and, unfortunately, the locator may not be handled with absolute care.

Weather can affect electronic locators. Before purchasing, determine if the unit has limitations when being used in various weather conditions, such as rain. Lastly, make sure the instrument features a multi-year warranty.

Your local dealer can help you determine which locator is right for your jobsite applications. For more information about McLaughlin locators, visit


For 90 years, McLaughlin has been actively involved in the drilling tool industry. During that time McLaughlin has developed a reputation for designing and building dependable, low maintenance trenchless construction equipment. McLaughlin takes pride in providing solutions for OEMs and the underground industry.

© 2016 McLaughlin Group, Inc.

All Rights Reserved.

Please fill out the information below