Article 250.52(A)(3) in the 2008 NEC

[north star]

& & &

I recently came across this memo from the City of Rogers, Arkansas requiring

compliance from their builders, in regard to the bonding [ i.e. - now known as

"connecting" ] of the steel reinforcement in the concrete footings vs. having

2 ground rods.

http://www.rogersarkansas.com/inspections/Electrical%20grounding%20memo.pdf

Interesting requirement by the City of Rogers, Arkansas, and other municipalities.

Some pics. on various installations

http://www.ashireporter.org/articles/articles.aspx?id=1676





Your thoughts! What is your AHJ requiring?

& & &

 

[jar546]

If there is more than 20' of rebar, it must be bonded and used as the GE. This is a requirement but the problem is that the footers are ofter poured before the electrical inspector gets involved. On a new construction that uses rebar in the footer, there is no reason to have ground rods.

The acorn in the bottom photo ain't gunna cut it. Not rated for connection to rebar.

 

[Bryan Holland]

I strickly enforce Section 250.50 of the NEC which requires all the electrodes that are present to be bonded together to form the grounding electrode system. So, if the design of the building or structure calls for steel reinforcement that meets description outlined in Section 250.52(A)(3), a concrete-encased electrode is present and must be bonded.

 

[jar546]

250.50 is where the requirement comes from

If there is no rebar then there is no reason to require it for the NEC requirements. If there is rebar that complies with 250.52(A)(3) then it must be bonded.

Only 1 builder around here does not use rebar in the footing (Seismic B)

 

[jar546]

Bryan, looks like we essentially posted the same thing at the same time without knowing it. Great minds think alike!

 

[Bryan Holland]

Following is a list of ground clamps listed for use with rebar...

There are currently only (2) “acorn” style clamps listed for use with REBAR:

Erico (Eritech): Model # CP58 - #4 rebar

ILSCO: Models # GRC-38, GRC-48, GRC-68 - #3, 4, and 5 rebar

Other UL listed Clamps for use with REBAR:

Erico (Eritech): Model # EK 16 / EK 17

ILSCO : Model # BGC-2T-DB, BGC-2P-DB, BGC-2PS-DB, BGC-4/0P-DB, BGC-4/0S-DB

Galvan: Model # JRD

Bridgeport: Model # RB-16, RB-17

Regal Fittings: Model # 8181

Consolidated Manufacturing International: Model # JRD

Greaves Corp: Model # J29-DB, J30-DB, J31-DB

NSI Polaris: Model # G140DB / GLC140DB

Sigma Electric: Model # C-11N, C-11BN, C-11, C-11D, C-11DN, RBC-1D

Halex Company: Model # C-11

Thermocraft: Model # JRD, JRD+

Thomas and Betts: Model # CC1C-45R, CC2C- 45R, CC10C-56R, CC20C-56R, CC40C-56R

 

[north star]

* * *

I know that the NEC requirement is there for the grounding of encased electrodes,

but some jurisdictions may not be aware of the requirement, or like us, we

cannot enforce it. That darned "powers that be" thingy again! :sad: It

would upset the "Apple Cart Kingdoms" around here.

Also, what do ya'll do if there are ' post tensioned type cables ' used in the

foundation. What about grounding encased "cables"?

FWIW, we are Seismic Zone "B" also. The builders around here use "post

tension type" foundations a lot. Not that they install them correctly, but

that is what is used here regularly.

Bryan,

Good list of approved clamps!

* * *

 

[fatboy]

We require it, the foundation crews stub it up like the picture shows, Sparky connects to it at roughin.

 

[Mule]

On post tension the concrete crew throws in a couple of pieces of rebar. They tried just throwing in one piece of steel but I showed them where a 20' piece of rebar bent and turned up wasn't totally encased. That they would need to add whatever distance that was turned up to the length of the rebar that was in the beam.

 

[pwood]

sometimes throwing a not required stick of rebar in the footings can save time and money over a rod. i noticed a 30" piece of freshly cut ground rod laying 25' from a freshly cut ground rod driven in the ground next to the new service. i told the homeowner to buy another rod and lay it in the 36" deep open trench nearby. "you can do that?" he said. some areas have bedrock and hardpan that makes the ufer option or 30" burial option look good.

 

[chris kennedy]

I strickly enforce Section 250.50 of the NEC which requires all the electrodes that are present to be bonded together to form the grounding electrode system. So, if the design of the building or structure calls for steel reinforcement that meets description outlined in Section 250.52(A)(3), a concrete-encased electrode is present and must be bonded.

Same here on Florida's east coast. I don't do dwelling units and I always clamp directly to the footers bottom bar with a listed clamp. I have never seen re-bar stubbed up out of the footer/slab like that. I belong to the camp that believes that the portion of the re-bar between the clamp and the pour is a grounding electrode conductor that does not meet the requirements of 250.62, not the grounding electrode described bellow.

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 (½ 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.