For utility companies and contractors, out of sight is never out of mind. Before any excavation, crews must always locate buried water and sewer pipes or risk costly repairs, service disruptions, or project delays. Contractors also need to find pipes damaged by corrosion, cold weather, tree roots, or other causes.
In both cases, burying tracer wire with water and sewer pipes is a simple way to locate those assets. Provided, of course, the tracer wire is installed correctly.
Tracer wire (also called locating wire or locator wire) is used to locate pipes and other buried utility lines. It is constructed using a solid copper and copper clad steel. The wire core is wrapped with a high molecular weight polyethylene (HMWPE) insulator that provides excellent moisture, chemical, and abrasion resistance. Different colored insulators denote specific types of buried utilities — for example, green for sewer lines and blue for potable water.
To lay tracer wire, crews place it length-wise along the buried pipe with an above-ground termination at each end. Once the wire is buried, utility workers and construction teams use a frequency generator (or transmitter) to send a current through the wire and a receiver to pinpoint the pipe’s location.
Buried tracer wire is subject to moisture, freezing temperatures, and other environmental challenges. Contractors should follow best practices when installing tracer wire to ensure the system will perform as designed — for years and even decades.
1. Effective Grounding
All electrical circuits require a ground to complete the circuit and work properly. If the installed tracer wire isn’t properly grounded, the signal will not leave the transmitter. Therefore, all dead ends or terminations must be grounded. This is typically done by attaching dead ends to grounding rods (usually made of copper, zinc, or magnesium) that are driven into the ground.
2. Tracer Wire Placement
Installers should tape tracer wire to water and sewer pipes every 8 to 10 feet. Taping keeps the wire from shifting away from the pipe during or after burial.
Some contractors make the mistake of taping the tracer wire to the top of the pipe. When the line is buried or dug up for repair, it’s easy for crews to scrape the pipe’s top surface with a backhoe and damage the wire. Therefore, it’s best to protect the tracer wire by taping it on the side of the pipe, either in the 3 or 6 o’clock position.
It’s also important to be consistent with the wire placement. If one day it’s taped on the left side of the pipe and the next day on the right side, locators will have difficulties pinpointing the pipe’s center. Engineers should always write wire placement into the job specifications. For example, “tracer wire placed on the east side of the pipe.”
3. Making the Right Connections
It is critical to terminate tracer wire properly. It’s normally exposed to harsh conditions, and over time, copper wire ends can corrode. Installers should always use purpose-built, waterproof connectors to terminate the wire. That will help maintain its integrity, even after being buried for years.
4. Tracer Wire for Ductile Iron Pipes
Many cities and jurisdictions use ductile iron pipes for sewer and water utilities. A common misconception is that because iron conducts electricity, buried ductile iron pipes are easy to locate and don’t require tracer wire.
That’s not the case. Often ductile iron pipes are wrapped in polywrap or exposed to earth and grounded. Either condition can distort transmitter signals and make pipes difficult to locate. Installing tracer wire is an inexpensive means to help crews quickly find buried ductile iron pipes.
5. Know the Local Specifications
Virtually every city or municipality has its own published specifications for using tracer wire. Those specs will include wire and jacket types and detail how the wire must be installed.
Contractors need to review and follow those local guidelines carefully. This ensures the installation’s long-term viability and helps installers avoid failing an inspection and the need to modify or replace their initial work. A short pre-construction meeting with local authorities will help clarify any grey areas before installation begins.
Some jurisdictions partner with wire manufacturers to offer training and certification for tracer wire installation based on those local specs. This training can save time and assure that installers will do the job correctly.
6. Post-Installation Inspection and Testing
The last step might be the most critical. Once the tracer wire is installed, the municipal representative and the contractor need to do an actual locate before they sign off on the job. If something’s not working, there’s no better time to address it.
It’s expensive and time-consuming for the contractor to dig it and fix the tracer wire installation if there is something wrong. But the alternative — not being able to locate the water and sewer pipes for repairs or before excavating — can be even more problematic.
Contractors and utility companies can save time, money, and avoid costly repairs by quickly locating buried water and sewer pipes. Employing best practices to install tracer wire will ensure crews can find those underground assets for years to come.
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