An Innovation in Wood Pole Testing

By Patrick Larsen, Regional Manager

After decades of working closely with power companies, we have become very knowledgeable about certain aspects of electric power infrastructure. CNUC began developing a service offering around this competency for our clients in 2020, beginning with visual inspections of electrical equipment and wood poles.

Electric utility companies must follow pole inspection and testing requirements defined by regulatory authorities. Historically, assessments have involved invasive techniques and dangerous, carcinogenic chemicals. In our quest to enhance our service offering, we began using a wood pole inspection instrument called a resistograph.

A resistograph is a mechanical resistance measurement device driven by a drill motor. It uses a long, thin needle which is inserted into the wood pole to measure its density and identify areas of decay. The device reads variations in the resistance to torque. Based on these variations, the instrument provides an instant, detailed report of the pole’s internal condition, including a pass or fail rating and decay percentage.

The resistograph delivers actionable insights quickly, without the need for highly invasive drilling. Measurements take less than one minute and can be completed by one person. This technique does not involve destructive drilling, excavation, or the chemical usage typically associated with other methods. The resulting data helps our clients manage wood pole assets and avoid unnecessary pole replacement. This specialized tool can also be used to perform a Level 3 International Society of Arboriculture Tree Risk Assessment.

The resistograph helps us mitigate negative environmental impacts associated with traditional inspection methods, while delivering the quality data our clients need to achieve regulatory compliance. Non-destructive wood pole testing is something we are excited to have in our arsenal as we inspect more than 100,000 wood poles each year.