Pole Inspection Methods
Is there a national standard for pole inspection?
Although the National Electrical Safety Code defines minimum safety factors for strength, there isn't a national inspection specification. Several states have adopted inspection mandates. In all other cases, utilities are free to choose inspection methods that meet their requirements.
Defining the Pole Inspection Process
The keys to pole inspection are identifying decay, measuring defects and estimating the percent remaining strength to determine pass/fail. Osmose introduced StrengthCalc® and LoadCalc® software to increase the precision of these calculations. Attempts to develop pole inspection instruments have not yet fully succeeded. Wood is a highly variable material; there are many possible decay patterns and they differ by species. The most accurate option remains a highly trained, professional inspector using time-proven procedures and tools.
Pole Inspection Methods Review
- Visual Inspection, or Visual and Sound is suitable for identifying gross defects visible above the ground level.
- Sound & Bore allows the inspector to bore inspection holes after hammer sounding identifies areas where decay is suspected. A shell thickness indicator may be used to measure internal decay.
- Partial Excavation Plus Sound and Bore allows the inspector access to a portion of the pole below grade, helping to identify external decay and termites.
- Excavation to a Depth of 18" to 24" Plus Sound and Bore allows the most complete access to the decay-prone region of poles, where moisture and oxygen encourage decay.
- Electronic Inspection Devices - these instruments typically depend on theories, such as frequency or time of flight of a sonic wave, or physical characteristics such as hardness to identify anomalies. The Shigometer differs from others in that it can identify early stages of decay, but it is not a pass/fail device.
The Realistic Expectation of an In-Place Wood Pole Inspection Program
Selecting Your Pole Inspection Method
The species and ages of poles in your system, and previous inspection and treatment history are factors for consideration. We can help you to match your program objectives with an inspection method, optimizing your maintenance investments.
For assistance with inspection methods, please contact Tom Pope at 770-632-6783 or [email protected].