![]() Many electrical engineers believe a Ufer grounding system without any of the extra connections listed above should suffice for most situations with large foundations/footings. The NEC and IEEE do not specifically address these details. These supplemental connections add to the cost of the system and also add to the problems of installation coordination between trades. Is it required to run a separate electrical wire connection (installed by electrical trade) from the footing (rebar/anchor bolt) to the structural steel column? Does it assume a bolted connection of the anchor bolt to the column is not adequate? This again requires the simultaneous presence of electrical and concrete trades.Is a separate electrical wire connection (installed by electrical trade) required to connect the foundation to earth even though the foundation sits in earth itself? The installation of such a connection requires that electrical trades be on site early with concrete trades.Ĭonnection of anchor bolt to steel column. ![]() But if concrete is a good conductor and there are multiple foundations/footings, then why is this connection needed? Is it because the rebar itself is the electrode and not the concrete encasement? Is a separate direct connection of rebar to at least one anchor bolt required even though concrete itself is a conductor? There is some belief that without this connection a lightning strike will cause the footing to explode due to the presence of moisture in the concrete.Is more than the usual tie wire connection provided by the foundation contractor required? Should they be welded, thus adding to the cost?.The lack of detailed Ufer grounding standards can be demonstrated by the following design issues: Connection of rebar to rebar The episode ultimately encouraged “never again” attitudes.Ĭurrently, there are National Electrical Code requirements for concrete encased electrodes including length and diameter of rod and amount of concrete encasement, but there are no real consensus standards regarding the details of the system. The inspector was dismissed by the client and subsequently filed a complaint to the State Board who took no action. The client’s inspector rejected the installation during final inspection although the Ufer system was indeed safe and met all Codes. In one illustrated case, concerted efforts were made to reduce plant construction costs and an Ufer system was designed and installed for a large chemical plant in the Gulf Coast area. Certain National Electrical Code interpretations.A belief that “grounding is cheap” compared to total plant cost.Lack of current consensus & standards for concrete encased electrodes.Lack of attention paid to grounding in general.Lack of motivation to try something “new”.Fear of failure during final inspection.Lack of understanding of the use of concrete encased electrodes.The belief that the buried loop and rod system provides lower resistance.There is much more experience with the ground loop and rod method.However, Ufer grounding in large process and power plants is not widely accepted for a number of reasons including: In addition to cost savings, underground corrosion due to the presence of differing metals, primarily copper and steel, can be mitigated by eliminating copper underground. In addition, eliminating the need for early and often inefficient electrical engineering and construction allows for fast track construction with a minimum amount of rework. ![]() Reducing or eliminating buried ground loops and ground rods generates savings. The use of concrete encased electrodes, commonly referred to as Ufer grounding, can save much money and time on new construction of large industrial facilities such as process, power, and pharmaceutical plants. Photo: Rebar cage with embedded Ufer concrete encased grounding electrodes (before concrete pour) The author recognizes the subject is somewhat controversial among electrical engineers and designers. This article is intended to stimulate thought and discussion on concrete encased grounding electrodes (Ufer grounding) and is the result of an outgrowth of a recent assignment the author assisted with. ![]()
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