What is Ufer stand for ?
The right terminology for the the Ufer ground according to the National Electrical Code (NEC) is Concrete-encased Electrode section 250.52 (A)(3).
The Ufer is the common word being used among the construction workers and electricians.
Ufer Ground Accessibility
All mechanical connectors are used to connect the electrical panel grounding conductor to the Ufer (rebar) are required to be accessible. An access panel on the exterior or interior walls is required.
However, if the connection is irreversible, using exothermic welding or a listed compression connector, instead of being a mechanical clamp, though, then you can pour concrete over it.
It is recommended to make an access for future installations, electrical inspectors will be asking to verify the existing grounding system when upgrading the electrical meter or/ and install new solar system.
Accessibility. All mechanical elements used to terminate a grounding electrode conductor or bonding jumper to a grounding electrode shall be accessible.
Exception No. 1: An encased or buried connection to a concrete-encased, driven, or buried grounding electrode shall not be required to be accessible.
Exception No. 2: Exothermic or irreversible compression connections used at terminations, together with the mechanical means used to attach such terminations to fireproofed structural metal whether or not the mechanical means is reversible, shall not be required to be accessible.National Electrical Code
Ufer ground electrical code requirements
Ufer is required to be 20 ft. long minimum and it shall be one continues piece, or if in multiple pieces, use a rebar tie wires or exothermic welding to achieve the 20 ft length and it shall be covered with a minimum of 2 inches of concrete.
The Ufer (concrete-encased electrode) required to consist of one of the following according to NEC section 250.52 (A)(3) (1)(2),
- A minimum of No. 4 rebar (half inch diameter).
- Bare copper conductor not smaller than 4 AWG.
It shall be installed in the footing to have a direct contact with earth not above the slab on grade because of the vapor visqueen which goes on top of the soil will act as a barrier between the Ufer and earth.
Before pouring footings for a new house or an addition, You should spot the location of the electrical panel and add a minimum #4 rebar, 20 feet long in the footings. #4 Rebar is sufficient for 100 and 200 amps Panel.
Ufer ground VS Ground rod
|Grounding Method||Ufer Ground||Ground Rod|
|Size||#4 steel /|
4 AWG Copper
|5/8″ Rod Copper|
|Length||20 ft||8 ft|
|Contact Surface||Concrete||Any Ground|
Ufer ground can be used as the main grounding system and it is not required by the national electrical code to add a ground rod in addition to the Ufer.
If you have two buildings located on the same lot, for example, if the garage and the main house are not attached and each building has a separate footings and an electrical box then each detached structures require a separate ufer ground when pouring new footings.
It also can be designed by an electrical engineer to be used as the main ground for high rise buildings. It was proved to be affective and its commonly used in new constructions.
Why is Ufer Grounding Important?
Having appropriate grounding, both for electrical Panels, switch gear and the building continues foundation, improves protection against lightening strikes.
Ufer grounding is contained inside any building which prevent ant trip hazard compared to grounding rods located on the outside.
Ufer ground history
Ufer was named after Herbert G. Ufer, he was the former western superintendent for Underwriters’ Laboratories, In. and he was given the task in world war II to find alternative ways for a new grounding system to protect buildings from lighting strikes.
Due to the dry soil conditions, there was a need for a working grounding system since the tradition water grounding and regular ground rod were not efficient in Arizona desert.
The idea of the Ufer was to found a lower cost and more affective than the traditional copper rod grounds for these dry locations.
Ufer was used as a grounding scheme based on encasing the grounding conductors such as steel rebar or a copper conductors in concrete.
This grounding system proved to be very effective, and was implemented after within the electrical Codes.
Reference Code – National Electrical Code