Grounding Sonotubes

calicocal

Member
Location
Detroit, MI
I'm installing 12" Sonotubes with a plastic coating wrapped around the outside. I know that the note on NEC 250.52(3) says "Concrete installed with insulation, vapor barriers, films, or similar items separating the concrete from the earth is not considered to be in 'direct contact' with the earth." If the bottom of the Sonotube is not wrapped and is direct contact is that adequate for grounding even though the sides are?
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
I would consider this a design issue. What does your engineer-of-record say?

As an inspector, working to the NEC, I would say, "not considered to be in 'direct contact' with the earth"

Critique on a design spec:
Consider a 1' x 6' sonotube. (no, I don't know the length is 6' - just an example)
Side area is 18.8 ft^2
Bottom area is .78 ft^2
Total area is 19.6 ft^2
Only 4% of the area is in contact with earth.
Yep, that design sucks

So, give us some context. And it would likely help if we knew if you had a dog in the hunt.
 
In addition to what ice worm said, note that even without any plastic, that would not be considered a CEE. Further, there is probably no need for an electrode at a pole base. Considering those two thing, what are y'all trying to accomplish exactly?
 

Besoeker3

Senior Member
Location
UK
I'm installing 12" Sonotubes with a plastic coating wrapped around the outside. I know that the note on NEC 250.52(3) says "Concrete installed with insulation, vapor barriers, films, or similar items separating the concrete from the earth is not considered to be in 'direct contact' with the earth." If the bottom of the Sonotube is not wrapped and is direct contact is that adequate for grounding even though the sides are?
Sorry, ignorant Brit here.
Sonotube?
 

PaulMmn

Senior Member
Location
Union, KY, USA
Sorry, ignorant Brit here.
Sonotube?
Imagine the core of a roll of toilet paper or paper towels, blown up to humongous size. Typically anywhere from 6" diameter, up to sizes that can form the pillars of a highway overpass! Lengths for home users are typically in the 6-foot range.

Just like the TP cores, the Sonotubes are diagonally-wound; you can still see the diagonal line where the inner layer has imprinted on the concrete.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I don't think such a tube meets the requirements to be a CEE even if it has enough rebar in it.

250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(3) Concrete-Encased Electrode. A concrete-encased electrode
shall consist of at least 6.0 m (20 ft) of either (1) or (2):
(1) One or more bare or zinc galvanized or other electrically
conductive coated steel reinforcing bars or rods of not
less than 13 mm (1∕2 in.) in diameter, installed in one
continuous 6.0 m (20 ft) length, or if in multiple pieces
connected together by the usual steel tie wires, exothermic
welding, welding, or other effective means to create a
6.0 m (20 ft) or greater length; or
(2) Bare copper conductor not smaller than 4 AWG
Metallic components shall be encased by at least 50 mm
(2 in.) of concrete and shall be located horizontally within that
portion of a concrete foundation or footing that is in direct
contact with the earth or within vertical foundations or structural
components or members that are in direct contact with
the earth. If multiple concrete-encased electrodes are present
at a building or structure, it shall be permissible to bond only
one into the grounding electrode system.
The rebar if any would be vertical in such a tube and so does not meet the requirements of a CEE for vertical rebar in a foundation.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
... The rebar if any would be vertical in such a tube and so does not meet the requirements of a CEE for vertical rebar in a foundation.
... or within vertical foundations or structural
components or members that are in direct contact with
the earth.

Vertical components should be okay. Just looking at the physics they should work fine.
 

Mystic Pools

Senior Member
Location
Park Ridge, NJ
Occupation
Swimming Pool Contractor
Imagine the core of a roll of toilet paper or paper towels, blown up to humongous size. Typically anywhere from 6" diameter, up to sizes that can form the pillars of a highway overpass! Lengths for home users are typically in the 6-foot range.

Just like the TP cores, the Sonotubes are diagonally-wound; you can still see the diagonal line where the inner layer has imprinted on the concrete.
Oh Man. After reading that I gotta go!!! Where's the latest Northern Tool catalog, the newspaper, sports section-something!
One exit and no waiting:D
 
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