What are the ground rod requirements for manholes?

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Grounding rods for manholes are sized to reach deeper, moister soil and provide a stable, low-resistance path to earth. The standard practice is an 8-foot (2.4 m) rod with a 3/4 inch diameter because this combination offers enough length to reach suitable soil while providing sufficient surface area and mechanical strength. This size helps keep grounding resistance down in typical soil conditions and is the commonly used specification in telecom manhole grounding. The other options either don’t reach the standard depth or use a diameter that isn’t aligned with common practice, which can increase resistance or reduce durability.