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WOOD ARMS VS. STEEL ARMS FOR TRANSMISSION SYSTEM

Short Comparison between using wooden arms vs. steel arms in power transmission system.

Wooden crossarms used in power transmission system are lower in cost than steel arms of the same strength and, aside from the shorter life, the possibility of being shattered by lightning, and the risk of burning due to leakage current at 345kV and above, are satisfactory. On wood pole construction, the advantages of steel arms - resistance to lightning damage and longer life - are not usually sufficient to offset the insulation strength of wood crossarms.

In any event, lightning damage to arms is usually not a major operating problem; and on lines thoroughly shielded with overhead ground wires, crossarm and pole damage is practically eliminated. At higher voltages, crossarms are sometimes equipped with bonding wires to prevent leakage current from burning.

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