Ufer?

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Paul B

Senior Member
When we drive ground rods, they are outside near the service entrance. Do you find your Ufer coming up outside or is it inside below the panel? I have never put it anywhere except inside near the panel location. Yesterday a guy on the job asked why is it coming up inside instead of outside? I did not have a good answer. Also if there is rebar in the footer and you are using 20 foot of #4 copper, do you still tie it to the rebar?
 

maghazadeh

Senior Member
Location
Campbell CA
When we drive ground rods, they are outside near the service entrance. Do you find your Ufer coming up outside or is it inside below the panel? I have never put it anywhere except inside near the panel location. Yesterday a guy on the job asked why is it coming up inside instead of outside? I did not have a good answer. Also if there is rebar in the footer and you are using 20 foot of #4 copper, do you still tie it to the rebar?

There is two kinds of uffers. 1) one is rebar 20 ft min, and 2) bare copper wire 20 ft min.
Rebar type is kept inside to protect it from rust, and bare copper is kept inside the wall or free standing cabinet to protect it from physical damage.
 

Gac66610

Senior Member
Location
Kansas
we put two in, one close to electric service entrance and one close to the water entrance, this way when metal water systems, (sometimes they are close enough to gas entrance we can bond to it as well), are used we can bond from electric panel to ufer and from ufer to water entrance, as they are tied together through footings inspectors here allow it , and it can save some $$ since we dont have to run copper across the basement
 

Paul B

Senior Member
OK this morning the inspector required the 20 foot bare copper to be tied to the rebar in the footer. I tied it with tie wire while he looked at the rest of the job. I asked what do you tie it to when there is no rebar in the footer? He said you need saddles to hold it up off the dirt. Doesn't make sense to me, current path is thru the dirt eventually anyway. I was not going to argue, he holds the axe, and I have to deal with him for the rest of the job, the building side anyway.
 

wirenut1980

Senior Member
Location
Plainfield, IN
Does not make sense to me. Is the 20 ft of copper encased in the concrete? If so, that should do it right there. What do you mean by tie wires bonding the 20 ft of copper to the rebar? That does not sound like an approved method for connection to a GEC. The way I understand, the tie wires can be used to bond rebar to rebar, but not rebar to copper. I could be wrong.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I see no reason why you would need to connect them together. A CEE can be comprised of either 20' or more of 1/2" or larger rebar or 20' of #4 Cu. {250.52(A)(3)}

250.50 says that any electrode present must be used so if you have the 20' or more of 1/2" or larger rebar you must use a CEE. The CEE can be either the rebar or the #4 Cu so it's your choice. If I were installing both I would spend the extra few bucks and clamp them togehter but IMO it's not required.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
Does not make sense to me. Is the 20 ft of copper encased in the concrete? If so, that should do it right there. What do you mean by tie wires bonding the 20 ft of copper to the rebar? That does not sound like an approved method for connection to a GEC. The way I understand, the tie wires can be used to bond rebar to rebar, but not rebar to copper. I could be wrong.

My thought too! I thought that bronze was needed between copper and steel to prevent electrolosis. My inspectors have always made me sleeve the copper at each rebar crossing and bond with a listed clamp. Mostly schools have requierd this.
 

John120/240

Senior Member
Location
Olathe, Kansas
My thought too! I thought that bronze was needed between copper and steel to prevent electrolosis. My inspectors have always made me sleeve the copper at each rebar crossing and bond with a listed clamp. Mostly schools have requierd this.

What benifit does a sleeve at each rebar crossing provide ? What signifance that the

building is a school vs a strip mall vs office building ?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I am not sure I agree. If the rebar is present then I believe it must be used. It is your choice whether to put 20' copper in the footer- that is not required however the rebar being there makes it a requirement. I do both just because...:D but the rebar is all that is necessary. Make sure the rebat is at least 1/2" or it would not qualify as an electrode.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I am not sure I agree. If the rebar is present then I believe it must be used. It is your choice whether to put 20' copper in the footer- that is not required however the rebar being there makes it a requirement.

The NEC tells us that if multiple CEE's exist that we only need to use one. 20' of rebar could be one and the #4 cu would be another. Say I have two footings, one that has no rebar, but I installed 20' of #4 cu and the other has 20' of 1/2" rebar, I wouldn't need to connect anything to the one with the rebar. Put them in the same footing and nothing changes.

(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.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
What benifit does a sleeve at each rebar crossing provide ? What signifance that the

building is a school vs a strip mall vs office building ?
The sleeve, by that I meant a piece of schedule 40, keeps the two disimilar metals apart.

The significance of the school is that most commercial applications I have done merely require a copper conductor attached to the rebar, not 20 feet of copper buried in the footer and bonded to rebar (whereas school specs often require this) and residential usually just gets a pice of rebar stubbed out of the concrete to tie on to, but the tie is still required to be with a listed clamp in most cases.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
OK this morning the inspector required the 20 foot bare copper to be tied to the rebar in the footer. I tied it with tie wire while he looked at the rest of the job. I asked what do you tie it to when there is no rebar in the footer? He said you need saddles to hold it up off the dirt.

Technically correct. The copper wire Ufer would need 2" of encasement in all directions to qualify as a concrete encased electrode. You could have slapped a single clamp connecting the conductor to the rebar and used the rebar as the concrete encased electrode instead.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
My thought too! I thought that bronze was needed between copper and steel to prevent electrolosis. My inspectors have always made me sleeve the copper at each rebar crossing and bond with a listed clamp. Mostly schools have requierd this.

I would love to see the code reference to back up the inspector's request. 110.24 only refers to conductor terminations, and I have a really hard time believing that steel and copper with have a galvanic reaction when miles of copper plumbing is strapped with steel straps all over the world.

There is virtually no current alon this path under normal conditions, either.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
My inspectors have always made me sleeve the copper at each rebar crossing and bond with a listed clamp. Mostly schools have required this.

I see no reason to do this or that it's required by the NEC. I'm no metallurgist but just because two metals are different does not mean that they cannot be connected together. For example, copper lugs are connected to a steel enclosure with steel bolts, copper EGC's are connected directly to steel boxes with steel grounding screws, etc. We connect copper to steel everyday without issue.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
I would love to see the code reference to back up the inspector's request. 110.24 only refers to conductor terminations, and I have a really hard time believing that steel and copper with have a galvanic reaction when miles of copper plumbing is strapped with steel straps all over the world.

There is virtually no current alon this path under normal conditions, either.

Do a Google search of electrolysis between steel and copper. Here is a cut of a thing I found in the first 2 seconds.

THE GALVANIC SERIES
1. Aluminum 7. Tin
2. Zinc 8. Lead
3. Steel 9. Brass
4. Iron 10. Copper
5. Nickel 11. Bronze
6. Stainless Steel 400 12. Stainless Steel 300
Series Series
When any two metals in this list are in contact, with
an electrolytic present, the one with the lower number is
corroded. The galvanic action increases as the metals
are farther apart in the Galvanic Series. It is not always
true that there is greater corrosion the further down the
scale one goes. In certain cases one metal immediately
following another may be very corrosive.


The code does require corrosion prevention. I have never been allowed to lay my EMT across a copper pipe in the ceiling, without putting a dielectric between them.
 
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