IS 7683:1975 is the Indian Standard (BIS) for design, fabrication and maintenance of nail-jointed timber posts from small dimensional timber for overhead electric distribution lines for low voltage. This standard provides guidelines for the design, fabrication, and maintenance of nail-jointed timber posts. These posts are constructed from smaller, readily available pieces of timber and are intended for use as supports for low-voltage overhead electrical distribution lines, offering a cost-effective solution particularly for rural areas.
Code of practice for design, fabrication and maintenance of nail-jointed timber posts from small dimensional timber for overhead electric distribution lines for low voltage
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Factor of Safety on Working Load | 2.5 (Clause 5.3) | Not directly comparable; modern codes use partial safety factors on loads and material resistances (Limit State Design). However, traditional ASD methods often result in effective safety factors in the range of 2.0-3.0. | General principle from NDS (ASD) / Eurocode 5 (LSD) |
| Minimum Nail Spacing (Parallel to Grain) | 10d (where 'd' is nail diameter) (Clause 6.2.2.1) | Typically 10d for pre-drilled holes, or (5+5cosα)d for nails without pre-drilling, where α is angle of load to grain. For many cases, this is 5d-10d. | EN 1995-1-1:2004 |
| Minimum End Distance (Parallel to Grain) | 12d (Clause 6.2.2.1) | Typically 10d for pre-drilled holes, or (10+5cosα)d for nails without pre-drilling. For many cases, this is 10d-15d. | EN 1995-1-1:2004 |
| Minimum Edge Distance (Perpendicular to Grain) | 5d (Clause 6.2.2.1) | Typically 3d for pre-drilled holes, or (3+2sinα)d for nails without pre-drilling. For many cases, this is 3d-5d. | EN 1995-1-1:2004 |
| Pole Planting Depth (for 9m Pole) | 1.5 m (Appendix B) | Approx. 1.5 m (Common rule of thumb: 10% of pole length + 2 feet / 0.6 m) | Common US utility practice (e.g., based on RUS Bulletins) |
| Governing Standard for Preservative Treatment | IS 401: Code of practice for preservation of timber | EN 351-1: Durability of wood and wood-based products - Preservative-treated solid wood | BS EN 14229:2004 |
| Nail Penetration into Final Member | Full penetration is preferred; where not possible, nails should penetrate at least two-thirds the thickness of the last member. (Clause 4.1) | For shear connections, point-side penetration must be at least 4d. For withdrawal, penetration is typically specified as 8d to 12d. | EN 1995-1-1:2004 |