Someone please clarify for me for required ground rod spacing, here is what I recalled from NFPA780 and NEC:
NFPA780 (lightning protection system): the spacing between rods shall not be smaller than the sum of all ground rod length..
NEC article 250...spacing between ground rod is min. 6 feet.
So, which rule should we go with? If we go with NEC, we are ok at spacing ground rod 6' apart as minnimum. If we go with NFPA 780, we have to space them at least 24 feet apart (assume 8' long ground rod)...
Or ground rod spacing rule per NFPA-780 only applies to lightning protection system? I saw several electrical grounding details where they showed the rod either 20' or 15' apart for tri-rods system.