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IS 2203 : 1993Wooden cross arms

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ANSI O5.3 · RUS Bulletin 1728F
CurrentRareSpecificationMaterials Science · Timber and Timber Stores
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Link points to Internet Archive / others. Not hosted by InfraLens. Details
OverviewValues3InternationalTablesFAQ3Related

IS 2203:1993 is the Indian Standard (BIS) for wooden cross arms. 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

Overview

Status
Current
Usage level
Rare
Domain
Materials Science — Timber and Timber Stores
Type
Specification
International equivalents
ANSI O5.3-2015 · American National Standards Institute (ANSI), USARUS Bulletin 1728F-810 · Rural Utilities Service (RUS), U.S. Department of Agriculture, USA
Typically used with
IS 287IS 399IS 401IS 1141IS 1708
Also on InfraLens for IS 2203
3Key values2Tables3FAQs
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.
Frequently referenced clauses
Cl. 4Species of TimberCl. 5Dimensions and TolerancesCl. 6Prohibited DefectsCl. 7Permissible DefectsCl. 8Seasoning and Preservation
Pulled from IS 2203:1993. Browse the full clause & table index below in Tables & Referenced Sections.
timberwoodpreservative-treated timber

International Equivalents

Similar International Standards
ANSI O5.3-2015American National Standards Institute (ANSI), USA
HighCurrent
Solid Sawn Wood Crossarms, Crossarm Braces and Wood Products for Overhead Powerline Construction - Specifications and Dimensions
Directly covers manufacturing, materials, and dimensions of solid sawn wood crossarms.
RUS Bulletin 1728F-810Rural Utilities Service (RUS), U.S. Department of Agriculture, USA
HighCurrent
Specification for Wood Crossarms (Solid and Laminated) and Wood Braces
Provides detailed specifications for wood crossarms used in rural utility systems.
AS 3894.1-1991Standards Australia (AS), Australia
MediumWithdrawn
Cross-arms for overhead line systems - Timber
Covered specification, timber quality, and testing of Australian hardwood crossarms.
Key Differences
≠Timber Species: IS 2203 specifies Indian timber like Sal, Teak, and Deodar, whereas international standards like ANSI O5.3 specify North American species such as Douglas-fir and Southern Yellow Pine.
≠Strength Grading: ANSI O5.3 often requires timber to be stress-graded to a specific bending strength (e.g., 1900f), providing a quantitative performance measure. IS 2203 relies primarily on species selection and visual inspection for defects.
≠Standard Dimensions: The standard cross-sectional dimensions and lengths are different. IS 2203 uses metric sizes (e.g., 100 mm x 75 mm), while US standards use imperial-based nominal dimensions (e.g., 3-3/4 in x 4-3/4 in).
≠Preservative Retention Levels: While similar preservatives (like CCA) are used, the specified minimum retention levels can differ based on regional biological hazards and local wood species' permeability. For example, IS 2203 specifies 12 kg/m³ for CCA, which may differ from species-specific requirements in AWPA standards referenced by ANSI.
Key Similarities
≈Control of Defects: Both IS 2203 and its international counterparts provide extensive guidelines on limiting natural wood defects like knots, splits, checks, slope of grain, and decay to ensure structural soundness.
≈Mandatory Preservative Treatment: All standards mandate the preservative treatment of wood to protect against fungal decay and insect attack, recognizing it as essential for achieving a long service life.
≈Manufacturing and Finish: Requirements for general workmanship, such as ensuring pieces are sawn true to size, holes are drilled cleanly without excessive splintering, and marking for traceability, are common across all standards.
≈Moisture Content: All standards require the timber to be seasoned to a specific moisture content (typically below 25%) before preservative treatment to ensure proper penetration and minimize in-service cracking.
Parameter Comparison
ParameterIS ValueInternationalSource
Permitted Timber SpeciesSal, Teak, Deodar, KailDouglas-fir, Southern Yellow PineANSI O5.3-2015
Preservative Type (Example)Copper-Chrome-Arsenic (CCA), Creosote-fuel oilCCA, Creosote, Pentachlorophenol (Penta), ACQ, CA-C (references AWPA U1)ANSI O5.3-2015
Preservative Retention (CCA)12 kg/m³9.6 kg/m³ (0.60 pcf) for Southern Pine in severe exposureRUS Bulletin 1728F-810
Moisture Content before TreatmentNot exceeding 22%Shall be 25% or less (for waterborne treatment)ANSI O5.3-2015
Dimensional Tolerance (Width/Thickness)± 3 mm± 1/8 inch (≈ 3.2 mm) on sawn facesANSI O5.3-2015
Tolerance on Hole Diameter+1.5 mm, -0.0 mm+1/16 inch (+1.6 mm), -0.0 inchRUS Bulletin 1728F-810
Slope of Grain (Limitation)Not steeper than 1 in 15Not steeper than 1 in 12 (typical for structural grades)ANSI O5.3-2015
⚠ Verify details from original standards before use

Key Values3

Quick Reference Values
maximum moisture content20% (before preservative treatment)
tolerance on length± 10 mm
tolerance on cross section± 2 mm

Tables & Referenced Sections

Key Tables
Table 1 - Recommended Species of Timber for Cross Arms
Table 2 - Standard Dimensions of Cross Arms
Key Clauses
Clause 4 - Species of Timber
Clause 5 - Dimensions and Tolerances
Clause 6 - Prohibited Defects
Clause 7 - Permissible Defects
Clause 8 - Seasoning and Preservation

Related Resources on InfraLens

Cross-Referenced Codes
IS 287:2022Code of Practice for Design of Timber Structu...
→
IS 399:1966Classification of Commercial Timbers and Thei...
→
IS 401:2001Code of Practice for Preservation of Timber
→
IS 1141:1993Seasoning of timber- Code of practice
→
IS 1708:2014Methods of Testing Small Clear Specimens of T...
→

Frequently Asked Questions3

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.

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