- Location
- Bremerton, Washington
- Occupation
- Master Electrician
What code was the ufer ground first required?
When was the Ufer Ground first introduced into the NEC
- Thread starter tom baker
- Start date
- Status
bphgravity
Senior Member
- Location
- Florida
The concrete-encased electrode first shows up in the NEC in 1968. However, it was not require to used if water pipe or 'other available electrodes" were used.
A change came in 1978 requiring the concrete-encased electrode if avaibale on the premises.
And of course, the 2005 NEC requires the electrode when present...
A change came in 1978 requiring the concrete-encased electrode if avaibale on the premises.
And of course, the 2005 NEC requires the electrode when present...
Well what the heck is it?? I love this forum, come here and read everyday, but some of the abbreviations and whatnot really throw me off. Maybe this isnt an abbreviation at all, but what is ufer? The closest thing I know to that is uf cable.
Thanks in advance.
Thanks in advance.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The word Ufer is from the name of a guy who actually developed the CEE concept. It reality the two terminologies, Ufer and CEE are not really interchangeable.
Look here:
https://psitampa.com/informational-readings/the-ufer-ground/
Look here:
https://psitampa.com/informational-readings/the-ufer-ground/
- Location
- Massachusetts
A 'Uffer' is slang for what the NEC calls a concreate encased electrode in 250.52(A)(3)
It is called a Uffer becuse the man that devloped and tested type of the concrete encased electrode was named Uffer.
It is called a Uffer becuse the man that devloped and tested type of the concrete encased electrode was named Uffer.
LawnGuyLandSparky
Senior Member
From:
https://psitampa.com/informational-readings/the-ufer-ground/
The term "Ufer" grounding is named after a consultant working for the US Army during World War II. The technique Mr. Ufer came up with was necessary because the site needing grounding had no underground water table and little rainfall. The desert site was a series of bomb storage vaults in the area of Flagstaff, Arizona.
The principle of the Ufer ground is simple, it is very effective and inexpensive to install during new construction. The Ufer ground takes advantage of concrete’s properties to good advantage. Concrete absorbs moisture quickly and looses moisture very slowly. The mineral properties of concrete (lime and others) and their inherent pH means concrete has a supply of ions to conduct current. The soil around concrete becomes "doped" by the concrete, as a result, the pH of the soil rises and reduces what would normally be 1000 ohm meter soil conditions (hard to get a good ground). The moisture present, (concrete gives up moisture very slowly), in combination with the "doped" soil, make a good conductor for electrical energy or lightning currents.
Ufer techniques are used in building footers, concrete floors, radio and television towers, tower guy wire anchors, light poles, etc. Copper wire does not function well as a "Ufer" ground due to the pH factor of concrete (+7pH is common). The use of steel reinforcement as a "Ufer" ground works well and concrete does not chip or flake as has been found with copper. The use of copper wire tied to the reinforcement rods outside the concrete shows none of these problems.
The minimum rebar necessary to avoid concrete problems depends on:
The type of concrete, its content, density, resistivity, pH factor, etc.
Amount of concrete surface area in contact with the soil.
Soil resistivity and ground water content.
Size and length of the reinforcement rod, wire, or plate.
Size of the lighting strike current.
The following chart shows the conductivity of lightning current per foot of Rebar (reinforcement rod). Only the outside Rebar can be counted. Rebar in the center of the footer or foundation does not count in this calculation. In a trench footer only the rebar in the sides and bottom of the footer can be counted.
Rebar Diameter In Inches Surge Amperes Per Foot
.375 3400
.500 4500
.625 5500
.750 6400
1.000 8150
Mr. Ufer did not know what he had found until he experimented with various lengths of wire in concrete. Today’s informed engineer benefits from Mr. Ufer’s discovery and will tie in the bars of steel reinforcement in a building or other foundation to the building electrical ground. When bonded to the electrical ground, building steel, etc., the buildings reinforced floor and foundation become part of the building grounding system. The result is a much improved grounding system with a very low overall resistance to earth reference.
If Ufer grounding alone was enough, the manufacturers of ground rods would go out of business. But a Ufer ground alone it is not adequate. Few buildings, even those under construction today are built to take advantage of the Ufer ground. It is common to see the use of "Ufer grounding" in military installations, computer rooms, and other structures with very specific grounding specifications. It is not common in most industrial plants, office buildings and homes. More common today is grounding to national and local electrical codes. This will involve one or more driven ground rods connected (bonded) to the neutral wire of the electrical service entrance. The purpose of this bond is what is known as life safety ground. It is used for many other things but the code required life safety ground is why it is there to begin with.
https://psitampa.com/informational-readings/the-ufer-ground/
The term "Ufer" grounding is named after a consultant working for the US Army during World War II. The technique Mr. Ufer came up with was necessary because the site needing grounding had no underground water table and little rainfall. The desert site was a series of bomb storage vaults in the area of Flagstaff, Arizona.
The principle of the Ufer ground is simple, it is very effective and inexpensive to install during new construction. The Ufer ground takes advantage of concrete’s properties to good advantage. Concrete absorbs moisture quickly and looses moisture very slowly. The mineral properties of concrete (lime and others) and their inherent pH means concrete has a supply of ions to conduct current. The soil around concrete becomes "doped" by the concrete, as a result, the pH of the soil rises and reduces what would normally be 1000 ohm meter soil conditions (hard to get a good ground). The moisture present, (concrete gives up moisture very slowly), in combination with the "doped" soil, make a good conductor for electrical energy or lightning currents.
Ufer techniques are used in building footers, concrete floors, radio and television towers, tower guy wire anchors, light poles, etc. Copper wire does not function well as a "Ufer" ground due to the pH factor of concrete (+7pH is common). The use of steel reinforcement as a "Ufer" ground works well and concrete does not chip or flake as has been found with copper. The use of copper wire tied to the reinforcement rods outside the concrete shows none of these problems.
The minimum rebar necessary to avoid concrete problems depends on:
The type of concrete, its content, density, resistivity, pH factor, etc.
Amount of concrete surface area in contact with the soil.
Soil resistivity and ground water content.
Size and length of the reinforcement rod, wire, or plate.
Size of the lighting strike current.
The following chart shows the conductivity of lightning current per foot of Rebar (reinforcement rod). Only the outside Rebar can be counted. Rebar in the center of the footer or foundation does not count in this calculation. In a trench footer only the rebar in the sides and bottom of the footer can be counted.
Rebar Diameter In Inches Surge Amperes Per Foot
.375 3400
.500 4500
.625 5500
.750 6400
1.000 8150
Mr. Ufer did not know what he had found until he experimented with various lengths of wire in concrete. Today’s informed engineer benefits from Mr. Ufer’s discovery and will tie in the bars of steel reinforcement in a building or other foundation to the building electrical ground. When bonded to the electrical ground, building steel, etc., the buildings reinforced floor and foundation become part of the building grounding system. The result is a much improved grounding system with a very low overall resistance to earth reference.
If Ufer grounding alone was enough, the manufacturers of ground rods would go out of business. But a Ufer ground alone it is not adequate. Few buildings, even those under construction today are built to take advantage of the Ufer ground. It is common to see the use of "Ufer grounding" in military installations, computer rooms, and other structures with very specific grounding specifications. It is not common in most industrial plants, office buildings and homes. More common today is grounding to national and local electrical codes. This will involve one or more driven ground rods connected (bonded) to the neutral wire of the electrical service entrance. The purpose of this bond is what is known as life safety ground. It is used for many other things but the code required life safety ground is why it is there to begin with.
bphgravity
Senior Member
- Location
- Florida
Go here for an early paper on the CEE:
http://www.mikeholt.com/files/PDF/Use_of_Conc_Encased_GR_as_GE_Fagan_Lee_1970.pdf
http://www.mikeholt.com/files/PDF/Use_of_Conc_Encased_GR_as_GE_Fagan_Lee_1970.pdf
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