Project: T193700 #3727
 

This project is to review the need for and methods of grounding concrete walls and foundations around and within substations.

Scope of Study

Alternative fencing designs for substations may be made of a type which has concrete with reinforcing steel within the wall. Questions arise as to how to ground concrete walls or even if it necessary to ground it at all.

Within the substation, concrete foundations include reinforcing steel within them. The steel is often but not always bonded to the substation grounding system. The practice of bonding reinforcing steel to the grounding system is referred to as a Ufer grounding system. Ufer grounding systems are not a common and familiar terminology to many substation designers today.

Corrosion issues when grounding rebar in foundations is sometimes thought to be an issue of concern. There are also concerns on the civil engineering side that the concrete may be damaged due to current passing through the concrete. If current is passing through more than 6 inches, will it rupture or break? Structural concerns may be influenced by whether the concrete is in compression or not.

The project will also investigate and discuss:

  • Grounding of transmission tower footings
  • The use and application of conductive concrete products
  • The influence of treatment methods on concrete surfaces such as with epoxy coatings which would reduce water ingress into the concrete and thus affect the concrete conductivity
  • Considerations when composite poles are installed on the concrete foundation

In CEATI Report 3707, Grounding Practices for Concrete Poles, the failure of steel bolts was investigated. The conclusions and recommendations from Project 3707 should also be considered and discussed in terms of their applicability to grounding of concrete walls and foundations.

This project is to review the practices and methods along with the need to ground concrete walls and bond foundation reinforcing steel to the copper ground system. This project is to include a review and summary of Ufer grounding systems and their applicability to substation grounding systems.

Tasks in this project include but are not limited to:

  1. Literature search including standards and electrical safety codes
  2. Utility survey to identify common utility practices in grounding concrete walls and foundations
  3. Detailed discussion of Ufer grounding systems
  4. Preparation of a report summarizing results