Doug Miller wrote:

Not obvious if you are saying there is no grounding electrode at the
shower building. It is code required. Rods are notoriously poor, but the
easiest if an electrode is not now present. Code is 8' (as someone said)
and 2 are usually installed.

Actually, Code is 8' or to the depth of permanent soil moisture, whichever is
deeper. [Article 250.53(A)]

250.53-A is installation and is not whichever.
250.52-A-5 has requirements for the electrode - min 8'.

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