Code of practice for maintenance of wood poles for overhead power and telecommunication lines
1972 Edition

The standard suggests routine inspections every three years up to the twelfth year, then every two years thereafter. Detailed inspections should be conducted every six years up to the twelfth year, then every four years subsequently. Routine inspections involve shallow soil excavation and sounding the pole with a hammer, while detailed inspections require deeper excavation and thorough examination including rot depth measurement using increment borers.

Biological damage should be managed by first inspecting poles regularly for signs of termite or fungal attack, especially at ground level. Decayed areas must be scraped clean before treatment. The standard prescribes application of preservatives such as hot coal tar creosote or copper-based pastes either by brush or injection. Periodic retreatment is essential since preservative effectiveness diminishes over time. Detailed inspection records are to be maintained.

Replacement is mandated if the decay or defects surpass safe structural limits or if any allowable defect enlarges to more than 2.5 times its original dimension. Replacement poles should be treated solid or jointed wood types and installed at least one meter away from the original pole's position. Inspections determining these criteria involve both routine and detailed soil excavation and hammer sounding procedures.

The code specifies applying two generous brush coats of hot creosote or a 5% solution of pentachlorophenol in a petroleum solvent from the pole top down to 40–60 cm below ground level. This treatment is first applied after 12 years of installation and repeated at every detailed inspection. For rot found on the pole tops, soft portions should be removed and coated with pentachlorophenol solution, and cavities filled with a paste composed of pentachlorophenol and fly ash. Injectable preservative pastes are also used for deeper treatment around the ground line.

Mechanical damage repair involves thorough inspection to identify rot or structural issues. Poles not rejected for excessive damage receive remedial treatment similar to biological damage, including the application of hot creosote or pentachlorophenol solution in two brush coats extending from the top down to 40–60 cm below ground. Damaged areas are excavated, hammered to check integrity, and increment borers are used to assess rot depth. Borer holes are plugged with treated wood dowels to prevent further decay.