Hi Joe, thank you for your question regarding reversible and accessible grounding
electrode connections. There are a variety of different types of ground
electrode connections available in the market place, however they generally
fall into one of three (3) categories:
1. Welded (such as exothermic welding)
2. Irreversible mechanical (such as high-compression fittings)
3. Revisable mechanical (such as mechanical fittings that can be removed
3a. Rated for above grade only (often indoor only)
3b. Rated for below-grade direct burial
One of the most common grounding electrodes, is the standard 10-ft x 3/4-in
copper-clad driven rod which has many requirements under the National
Electric Code (NEC) (see Article 250), including the burial depth, length,
angle, resistance, and of course the type of connection used. NEC Article
250.10, 250.53(B), & 250.56 require that the connections to any electrode
must be made with properly rated clamps. If the rod is to be completely
buried, it must have either # 1, 2, or 3b from above. It may not have 3a.
We always recommend exothermic welding for buried connections.
In your case it sounds like you have a requirement for access to the rods.
We recommend that you install a cover box with a 10-ft ground rod and a 3b
rated clamp. That way you can have the rod buried at least 9.5-ft and only
have 6-inches of the top exposed, yet protected by the cover box. The box
can be installed flush to grade level. With the clamp above grade level, yet
in the box, you can always access the connection and maintain it.
The E&S Grounding Solutions Engineering Team