A Ufer ground is a concrete-encased grounding electrode. Under 2020 NEC 250.52(A)(3), it requires at least 20 feet of qualifying reinforcing steel at least ½ inch in diameter or bare copper 4 AWG or larger, with at least two inches of concrete cover. The footing or foundation must meet the rule’s location requirements and have direct earth contact.
The rules below refer to 2020 NEC Article 250.
What qualifies as a concrete-encased electrode?
Section 250.52(A)(3) provides two material paths:
- Steel: at least 20 feet of qualifying bare, galvanized or otherwise electrically conductive coated reinforcing steel, at least ½ inch in diameter. Permitted joining methods can create the required length.
- Copper: at least 20 feet of bare copper, 4 AWG or larger.
The electrode needs at least two inches of concrete cover. The concrete and electrode location must meet the section’s foundation or footing conditions, including direct contact with earth. Concrete separated from earth by insulation or a vapor barrier doesn’t meet that direct-contact condition.
Before the pour, check four things: qualifying material, 20-foot length, two-inch concrete cover and the footing’s contact with earth. Arrange the connection and required inspection while the electrode is accessible.
Watch: ground rods and concrete-encased electrodes
Follow JCR’s explanation with 2020 NEC 250.52 open. Compare the electrode types, then check the concrete, steel and earth-contact requirements in the example below.
Ground Rods vs Concrete-Encased ElectrodesWatch JCR’s lesson on YouTube ↗
Do you have to use it when it’s present?
Section 250.50 generally requires qualifying grounding electrodes present at the building to be bonded into the grounding electrode system. You don’t simply choose rods and ignore an available qualifying concrete-encased electrode.
There is an exception for existing buildings where qualifying reinforcing steel isn’t accessible without disturbing concrete. The rule also doesn’t require every separate concrete-encased electrode at a location to be connected when the conditions of 250.52(A)(3) permit bonding one.
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See CE courses and class datesIs the grounding electrode conductor always 4 AWG?
No. Don’t confuse the copper electrode itself with the conductor connecting to it.
The bare copper electrode option has a minimum size of 4 AWG. The grounding electrode conductor, or GEC, is sized under 250.66 and the applicable special rules. Under 250.66(B), the conductor serving only a concrete-encased electrode does not have to be larger than 4 AWG copper. This limit applies when the conductor does not continue to another electrode requiring a larger conductor.
Size the GEC under 250.66 first, then apply the 4 AWG maximum required size for this connection. Use the grounding electrode conductor sizing guide to work through the table and exceptions.
Practice question: does this electrode qualify?
A new footing contains 20 feet of ½-inch bare reinforcing steel, properly interconnected, with at least two inches of concrete cover. The footing concrete is directly in contact with earth. Which condition would disqualify it: increasing the rebar diameter, increasing its length, or placing an insulating barrier between the footing concrete and earth?
See the answer
The insulating barrier. It breaks the required direct contact between the concrete and earth. Larger reinforcing steel or additional qualifying length does not create that problem. Check all the conditions in 250.52(A)(3), not just the rebar size.
What a Ufer ground does not replace
It doesn’t replace the equipment grounding and bonding path back to the source. Earth is not the effective ground-fault current path used to operate an ordinary breaker or fuse.
It also doesn’t tell you where to bond the neutral. Service bonding and feeder-supplied panel rules are separate decisions. See the main bonding jumper explanation and equipment grounding conductor examples.
Common questions
Does the 25-ohm ground-rod rule apply to a Ufer?
The supplemental-electrode provision and 25-ohm exception in 250.53(A)(2) address a single rod, pipe or plate electrode. Don’t apply that specific rule to a concrete-encased electrode.
Can any coated rebar qualify?
No. The steel option requires an electrically conductive surface. Don’t assume an insulating coating satisfies the rule.
Can I use a shorter copper wire if it’s larger?
No. Increasing wire size doesn’t eliminate the required 20-foot length.
Examples use the 2020 NEC. References checked October 25, 2026.
