Is It True You Can’t Detect Plastic Pipes with a CAT? Find Out!

 If you have ever been on a site and heard someone say that plastic pipes are invisible to a CAT, then you have heard one of the most dangerous myths in the industry, because the answer is not as simple as yes or no.

While the literal answer is yes, a standard CAT does not detect a plastic pipe on its own, as plastic does not carry an electromagnetic signal; however, that is only half of the equation, and if you do not know how to proceed from that point, then you are leaving your job and your safety to chance.

The real question is how you can use your equipment to make those invisible services appear.

The Science of Why Plastic Stays Hidden

To understand the solution, one must first understand the problem. The way a CAT works is by detecting the electromagnetic fields emitted by metallic cables or pipes. Plastic does not emit an electromagnetic field because plastic is an insulator. It also won't pick up a signal broadcast by a Genny through induction. The mistake most operators make is when they run a standard sweep and find nothing. They then assume the trench is clear. This is exactly why CAT training is so important. During training, you will learn that a silent device does not mean a clear trench.

How to Bring Plastic into Focus?

The most common professional means of accomplishing this feat is through the use of a signal sonde or a traceable duct rod. This means that you are providing the CAT something to see as it travels through the network. Essentially, you are creating a temporary transmitter out of a non-conductive plastic pipe. Thanks to your CAT training, you will be able to determine the depth of this sonde as well as its path of travel through the network, thereby providing a 3D image of the plastic assets.

The Role of Tracer Wires and Marker Tape

In many contemporary installations, the utility companies now run a tracer wire with plastic gas and water mains. If one is informed as to where the connection is, it is possible to apply an active signal directly onto this wire. In some installations, detectable mesh or marker tape is buried above the pipe. While these are useful, they are not infallible. One has to be skilled enough to distinguish between the signal from a thin wire and bleed-through from a nearby high-voltage cable.

The Bottom Line

The idea is to move away from that beep-and-dig mentality. By learning how to effectively utilise accessories like dual frequency sondes or flexi-traces, you guarantee that no plastic or other type of utility is left lurking beneath your feet unseen.

Learning about the capabilities of your equipment is the first step to becoming a competent user of it.