Footing Rebar Bonding

A W Smith

Just had a call from my client that his footing inspection failed. seems I neglected to bond his rebar with a ground wire long enough to reach his electrical panel. This is new to me. I haven't dug a footer in a few years and have not heard of this. It is a simple 14 x 22 one car garage addition to an existing modular home built in the late seventies. The inspector is returning tomorrow. The client had already pulled his own permits, He is performing some of the work himself. and theres no mention or detail showing bonding on the rebar in the drawings. Inspector said it should have been there. We are scheduled to pour tomorrow at noon. I am hoping the client does the bonding properly with the correct gage wire and bonding clamp. What is the theory and reasoning behind bonding rebar in footings? Is it to supplement the grounding of the service panel? Or vice versa? I'm curious. Since I'm off today maybe ill stop at the library and look through the NEC. This garage is in Jackson NJ and must be built to sustain 100 MPH winds.The hurricane tie detailing scared off ED the carpenter who's brother in law owns the house. The guy ED worked for me 16 years ago. And talked me into helping him with this project. Even though I was confident Ed could have done it himself. So I'm just getting a day rate.

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Al Smith
http://www.awsmith.com

InPhase277

The rebar bond, or "ufer" as electricians call it, is both a supplement and a primary electrode. It can either be used to supplement a cold water electrode, like ground rods do, or it can be the primary electrode in lieu of the metal water line. But in any case it is supposed to be bonded to ground. Alot of times the concrete crew will just bend a 90 into a piece of the rebar so it sticks up out of the slab inside of a wall. The electrician can just clamp his wire on there. The wire is not required to be larger than #4.

InPhase277

TimNJ

I did an addition a couple years ago for a friend and the electrician alerted me to the bonding , but all he did was give me the clamps and a piece of wire about 6' long, enough to come out of the footing coil up in the crawl space. Inspector never even looked at it after the pour.

220/221

It gives the lightning a place to go.

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Just because it's within code doesn't make it safe.

Just because it's against code doesn't make it unsafe.

Magnettica

250.50 Grounding Electrode System.

All grounding electrodes as described in 250.52(A)(1) through (A)(6) that are
present at each building or structure served shall be bonded(A)(6) that comply with 250.56, or ......

(key word being "present" and it is since it's a new pour)

Exception: Concrete-encased electrodes of existing build-
ings or structures shall not be required to be part of the
grounding electrode system where the steel reinforcing bars
or rods are not accessible for use without disturbing the
concrete.



250.52 Grounding Electrodes.

(A) Electrodes Permitted for Grounding.

(3) Concrete-Encased Electrode.

An electrode encased by at least 50 mm (2 in.) of concrete, located within and near the bottom 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 (1⁄2 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 effec-
tive means.

250.66 (B) Connections to Concrete-Encased Electrodes.
Where the grounding electrode conductor is connected to a
concrete-encased electrode as permitted in 250.52(A)(3),
that portion of the conductor that is the sole connection to
the grounding electrode shall not be required to be larger
than 4 AWG copper wire.

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mdshunk

The way they interpret it in my area is that if the footer inspector didn't catch it on the footer inspection, the rebar electrode is not longer "present". I think they enforce it that way because the inspections in my area are done by a 3rd party private company, and often they send out "combo inspectors" who know only a tiny bit about each thing they inspect. I notice that some new construction has the same guy's signature on the permit card for most every inspection for the job.

A W Smith

The owner told me that when the inspector was there this morning he (the inspector) had to call someone for clarification. I assume he called the electrical inspector.

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Al Smith
http://www.awsmith.com

Celtic

That would be my guess also....the EI down there is pretty sharp...especially with the HO permit in effect

Here is a nice picture or two:

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A W Smith

Judging by that second picture the bonding method that the homeowner used today may not pass. He described a stranded wire that he stripped two portions of and clamped to the two half inch Rebar's. But thats what the footing inspector instructed him to do. He said he went to an electrical supply (not a box) and explained to the counter person what he was doing.

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Al Smith
http://www.awsmith.com

Celtic

Here are some more pictures:

http://www.iaei.org/subscriber/magaz...d/johnston.htm






If these 2 pictures are missing goto: http://www.erico.com/products/ERITECH_RC70_RC100.asp

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Jim M

At the last Code update class I took the inspector told me their take on this was if rebar was installed it was present.

If you didn't get the job until after ther footer was poured plan on getting out a jackhammer to access it. They would not accept driven rods in place of the ufer.

mdshunk

Call me crazy, but doesn't jackhammering a footer require an engineer sealed detail print for the repair method?

Magnettica

And wouldn't the exception in 250.50 apply here since the EC is coming in after the pour?

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A W Smith

What electrical? I didn't even see a layout on his approved plans, Yet I know for a fact an outside light by the back door and garage light will be required. He did his little attached garage addition on graph paper.

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Al Smith
http://www.awsmith.com

Celtic

No.

"Errors and omissions" are not an exception

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rino1494

Funny thing is, code doesn't require rebar in footings. What are you supposed to do in this case then ?? Around here, every mason sticks up a piece of bar, but nobody attaches to it, because the inspector doesn't check it.

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Celtic

No rebar?
Toss 20' of stripped #4 in the mix...as shown in the lower picture here:

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wesc

WTF is the point in that?! I'm an electrical engineer that designs power lines for a living, and lives/breathes protect from electricity. Kinda glad I dont' have those "codes" out here. It doesn't even really contact the ground.

By attaching the rebar to ground, you are letting the rebar get charged when a lightning cloud comes overhead, and the chances of lightning going for that rebar are much much greater. Much better to have it floating in the concrete not touching anything.

thom

Interesting the way it's done in different jurisdictions.

Here, the concrete contractor provides a bent up piece of rebar that projects about 24" above the stemwall into the framed wall. We connect a #2 bare (depending on service size) copper to the re-bar with a standard ground clamp. This connection must be accessible so we bend the bar so that it's adjacent to a stud, screw a 4X4 mud ring to the stud then at trim put a double blank cover on it.

Magnettica

I have a UFER now that was installed on the wrong side of the house. The basement concrete has not been poured yet. Is this method applicable here?

(Btw, where has Celtic been for the past few days?)

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