The NEMA Publibication mentioned by mjl2023 is quite excellent as applied to fresh water incidents or sweet water as it is sometimes called.
Exposure to salt water splashing or spray with only surface contact can be easily resolved using plenty of warm fresh water to remove any salt with...
Thanks to dpc, busbar, and ongchazira for their correct responses.
We are a little embarrased by this incident as we know what the described measurements indicate. We just could not find the groundfault.
However, after further investigation we found that the grounding resistors and...
