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 ~ National Lightning Safety Institute ~

Section 5.3.4

Relative Advantages and Disadvantages of the Principal Types of Earth Electrodes

Type Advantages Disadvantages
Vertical rods Simple design. Easy to install in good soils. Hardware readily available. Can be extended to reach the water table. High impedance. Hard to install in rocky soil. Step voltage on earth surface can be high under large fault currents or during a direct lightning strike.
Plates Can achieve low resistance contact in limited area. Most difficult to install. Should be installed vertically.
Horizontal bare wires
Low impulse impedance. Good RF counterpoise when laid in star pattern. Subject to resistance fluctuations with soils drying. Not recommended with unstable soils.
Incidental electrodes
(water pipes,
ufer grounds,
buried tanks)
Can achieve very low resistance in certain applications. Little or no control over future alternations. Must be employed with other electrodes, not as sole electrode.
Ring ground Straightforward design. Easy to install around existing facility. Hardware readily available. Very efficient due to volume. Problems with asphalt and concrete around the facility? Not desirable where large rocks are near surface.


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