What species of timber are permitted for cross arms?

Timber species are selected based on structural strength, natural durability, and treatability, typically categorized into groups as listed in Table 1.

Is preservative treatment mandatory for wooden cross arms?

Yes, to ensure longevity against termites, fungi, and weather, chemical pressure treatment conforming to IS 401 is strictly required.

What are the commonly prohibited defects?

Decay, live borer infestations, large shakes, cross-grains, and splits that compromise structural integrity are prohibited.

IS 2203

: 1993

Wooden cross arms

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This standard specifies the requirements for wooden cross arms used on overhead electrical power and telecommunication poles, covering acceptable timber species, dimensions, permissible defects, and preservation methods.

Wooden cross arms

Quick Reference Values

maximum moisture content20% (before preservative treatment)

tolerance on length± 10 mm

tolerance on cross section± 2 mm

Practical Notes

Wooden cross arms are highly susceptible to weather and biological decay; ensure strict adherence to IS 401 for preservative treatments like CCA or Creosote.

Inspect bolt hole areas closely, as knots, shakes, or grain deviations in these zones significantly reduce the bending strength of the arm.

This material has been largely replaced by steel (MS channels) and FRP in modern infrastructure due to durability and maintenance considerations.