grounding electrode question

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kitsr

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Ref 250.52 20 feet 1/2" rebar as grounding electrode if i have four sections of 5 foot rebar in a column would this count as the 20 feet required for this section
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
As long as they are connected your good.


250.52(A)(3) Concrete-Encased Electrode.

An electrode encased by at least 50 mm (2 in.) of concrete, located horizontally near the bottom or vertically, and within that portion of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (? in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means. Where multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Highlighting another portion of Chris' quote:

(3) Concrete-Encased Electrode. An electrode encased by at least 50 mm (2 in.) of concrete, located horizontally near the bottom or vertically, and within that portion of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (? in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means. Where multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.

Would this not mean the re-bar (or at least 20 ft of it) would have to be in a potion of the column that is in direct contact with the earth ?
 

iMuse97

Senior Member
Location
Chicagoland
Highlighting another portion of Chris' quote:

(3) Concrete-Encased Electrode. An electrode encased by at least 50 mm (2 in.) of concrete, located horizontally near the bottom or vertically, and within that portion of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (? in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means. Where multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.

Would this not mean the re-bar (or at least 20 ft of it) would have to be in a potion of the column that is in direct contact with the earth ?

That's been my take on it.
 

iMuse97

Senior Member
Location
Chicagoland
I've often wondered, is there any rebar available that is LISTED for this purpose? Just playing devil's advocate....

if it was listed, could you read the imprint behind all the oxidation? Humor aside, --Don't know. Good question. Should it be listed? Does it have to be? Driven electrodes obviously must be. Why not these?
 

hurk27

Senior Member
if it was listed, could you read the imprint behind all the oxidation? Humor aside, --Don't know. Good question. Should it be listed? Does it have to be? Driven electrodes obviously must be. Why not these?

driven rods smaller then 5/8" are only required to be listed, if you drive a 5/8" or larger your good to go without a listing.

250.52(A)(5)(b) Electrodes of rods of iron or steel shall be at least 15.87 mm (5/8 in.) in diameter. Stainless steel rods less than 16 mm (5/8 in.) in diameter, nonferrous rods, or their equivalent shall be listed and shall not be less than 13 mm (? in.) in diameter.
 
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