A single rod, pipe, or plate electrode shall be supplemented by an additional electrode of a type specified in Sections E3608.1.2 through E3608.1.6. The supplemental electrode shall be bonded to one of the following:
- A rod, pipe, or plate electrode.
- A grounding electrode conductor.
- A grounded service-entrance conductor.
- A nonflexible grounded service raceway.
- A grounded service enclosure.
Where multiple rod, pipe, or plate electrodes are installed to meet the requirements of this section, they shall not be less than 6 feet (1829 mm) apart.