Tracer Wire vs. THHN Wire

Kelly Benjamin
May 2, 2017

*Tracer wire is a big part of what we do here at Performance Wire and Cable. The purpose of this post is not to say electric wire tracer is better than THHN wire or vice-versa. It intends to point out differences between the two and help explain why the two options are suitable for different applications. 

We have seen some articles that debate using tracer wire for this or THHN wire for that; we’ve also received questions about the difference between the two wires. Read on for the answers.

First off, what is tracer wire? What’s THHN wire?

Multicolored Tracer Wire made in USA from Performance Wire and CableTracer Wire: while used in general purpose wiring circuits, machine tools, and appliances, tracer wire’s primary use is to locate buried water/gas pipes and fiber optic cables. That’s why it is often referred to as underground locator, locating wire, electric wire tracer and more.

THHN Wire: Thermoplastic High Heat-resistant Nylon (THHN) is also used in machine tooling and some appliances, but its main claim to fame is being the most popular type of building wire. In simpler terms, THHN wires transmit electricity throughout buildings.


We’ll start with THHN wire in this section as it makes describing tracer wire below a little easier. As stated above, THHN stands for thermoplastic high heat-resistant nylon. The main difference is the nylon coating that this wire possesses. The actual wire is either copper or aluminum (as it must conduct electricity). The next layer is polyvinyl chloride – better known as PVC. Last comes the nylon coating.

Underground tracer wire can be referred to as either TH wire or THW wire. Like THHN wire, the TH stands for Thermoplastic Heat resistant. The added “W” in THW signifies that the wire is also resistant to water. Unlike the nylon, locator wire’s outer layer consists of a polyethylene coating.


THHN wire is approved for up to 600 volts, which satisfies most residential and industrial electrical needs. It rates up to 90 degrees Celsius in dry settings. Unless it is THWN rated, THHN wire does not perform well in wet environments. The nylon outer layer gives the wire much flexibility, which is crucial for wiring and cabling needs.

Tracer wire, or electric wire tracer, is comparable to THHN wire in many aspects. It also is approved up to 600 volts and performs well up to 90 degrees Celsius. It ranges from 8-14 AWG. Tracer wire can withstand up to 75 degrees Celsius in wet conditions thanks to its polyethylene coating. This outer layer also provides resistance to corrosion, water damage, and exposure to gas and oil. That’s why it is ideal to use for locating gas pipes, water tubing and more.

For a more comprehensive description of tracer wire benefits, click here.


THHN is just a bit cheaper than tracer wire; hence its claim to being the most popular building wire. In some residential, industrial or construction scenarios that require a lot of building wire, THHN wire is the logical choice because it can create substantial savings.

However, problems arise when contractors choose THHN for applications and uses that would be better suited for tracer wire. They may see initial cost savings, but constant repair, maintenance, and replacement costs can quickly turn those immediate savings into a monumental loss over a long-term period. Notice how the THHN wire (black wire in the middle) wore down compared to the yellow tracer wire on the outside.

yellow and black wires

We hope this feature cleared up any confusion you had about the differences between THHN wire and tracer wire. Visit our blog for more articles on the cable and wire industry.