HANDBOOK REQUIREMENTS - Central Maine Power Company

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2. Metal frame of building or structure, where
effectively grounded.
3. Concrete-encased electrode consisting of at least 20
feet of 1/2 inch reinforcing bar or #4 AWG copper wire
encased within and near the bottom of a concrete footing or
foundation.
4. Ground ring consisting of a minimum of 20 feet of bare
copper wire not smaller than #2 AWG, in direct contact
with the earth, buried at least 30 inches deep all the way
around the building or structure.
5. Driven ground rod or pipe, which must be at least 8
feet long; consisting of rod not smaller than 5/8 inch
diameter made of galvanized steel, or copper clad steel; or
pipe not smaller than 3/4 inch trade size and protected from
corrosion. At least 8 feet of electrode must be in contact
with the soil, and it must be driven vertically or up to a 45°
angle where rock is encountered. As an alternative, the
electrode may be buried in a trench that is at least 30 inches
deep. See Notes 1 and 2, below.
6. Other listed electrodes for grounding shall be
permitted.
7. Metal plate electrode with at least 2 square feet of
surface in contact with soil and buried at least 30 inches
deep. Iron or steel plates shall be at least ¼ inch thick;
nonferrous plates at least 0.06 inch thick. See Notes 1 and
2, below.
8. Local underground metal piping system or tank (a gas
piping system shall NOT be used as a grounding electrode).
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