Single Pole or Dual Pole—What’s the Difference?

When spec’ing a truck, selecting between a single pole system and a dual-pole system can be a larger decision than people realize. However, we are here to help! In this quick tip, we will compare the purpose and benefits of a single pole vs. a dual pole system so you can feel confident in your decision and choose a system that is perfect for your needs.

Single and dual pole systems serve the same purpose; they form an electrical connection between the tractor and the trailer. This connection is what moves electrical power between the two and is what is most often used to charge liftgate batteries.

The main difference between these systems lies in the connection they make. For electricity to flow, an electrical connection requires two paths: one path from the source to the load, and a second (return path) from the load to the source.

In a single pole connection, the chassis of both the tractor and trailer provide the return path from the load to the source, with the ground connection being made through the 5^TH wheel. Since the 5^TH wheel does not always provide a good connection (depending on how much contact is being made between it and the king pin plate), this results in a system connection that is often intermittent and unreliable.

An intermittent ground circuit, in this case generally due to 5^th wheel grease, turning, or corrosion, can cause interruptions in the circuit.

In a dual pole connection, however, copper wires provide both paths—one single positive cable and one single negative connection between the tractor batteries and the trailer batteries, connected with an insulated plug. This results in a system that has a better, more solid electrical connection that will be reliable and long lasting.

So, why is a single pole system even in the running when a dual pole provides a better and more reliable electrical connection? Simply put, the only advantage to the single pole costs slightly less.

Purkeys always recommends a dual pole over a single pole.

Purkeys experienced customer service and sales representatives are available to answer your questions, provide on-site training, and help you select the right products for your fleet. Contact us today!

Check back later for the best ways to use a dual pole to power your liftgate or other auxiliary equipment!