I am working on a industrial facility that has 2500KVA, 12.7KV-480/277V service. In the past I have always specified a triad ground rod system at a service entrance. The triad ground rod system has been based on utility requirements and best engineering practices. The utility at this site does not require a redundant ground. Are there any codes or standards that I could reference to back up the use of a triad ground rod system at a service entrance.