Mike Dolt Enterprises
Mike Dolt Enterprises
User: 02harleyfxdl, Location: Chapel Hill, NC
Asked on: Thursday, March 24, 2011 at 3:49 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:13 am EDT
Question: When the concrete encased electrode utilizing #4 rebar is utilized as the method of grounding on a residential structure and the re-bar is turned verticle to provide the tie in for the grounding conductor please explain the following: If the stub up through the foundation wall exits the wall on the exterior of the wall, below grade with 2-3 feet exposed above grade is this being allowed. Understanding that unprotected re-bar is required to be encased in concrete per ACI 318, but it does not mention re-bar being used as the grounding electrode system. Is there any other justification out there that can be pointed out in black & white othere than the IRC 3608 section and the ACI 318?
NEC Requirements
The National Electrical Code (NEC) does not explicitly address the location of the stub-up for the concrete-encased electrode if it is turned vertical. However, it does state that the grounding electrode conductor (GEC) must be connected to the grounding electrode in accordance with the equipment listing requirements (NEC 250.56).
IRC Requirements
The International Residential Code (IRC) section 3608 requires that the grounding electrode for a residential structure be embedded below permanent grade at least 2 feet in earth or concrete. However, it does not specifically address the location of the stub-up for the concrete-encased electrode.
ACI 318 Requirements
ACI 318-19, "Building Code Requirements for Structural Concrete," states that reinforcement placed near the surface of concrete that will be exposed to moisture, water, or ice must be protected against corrosion by corrosion-resistant reinforcement or other means (ACI 318-19, Section 10.5.
8.2).
Other Justifications
While there is no clear black-and-white justification for allowing the stub-up to be located below grade on the exterior of the foundation wall, the following arguments can be made: Grounding Effectiveness
Placing the stub-up below grade ensures that it is in contact with moist soil, which is a good conductor of electricity. This ensures that the electrode is effective in grounding the electrical system.
Corrosion Protection
The stub-up is protected from corrosion by the concrete encasement, even if it is located below grade.*
Safety
The stub-up is located below grade, so it is not a tripping hazard or a hazard to children playing near the structure.
Conclusion
While there may not be a specific code requirement that explicitly allows the stub-up to be located below grade on the exterior of the foundation wall, the arguments presented above provide justification for allowing this practice. Ultimately, the decision should be made on a case-by-case basis, considering the specific site conditions and the requirements of the local authority having jurisdiction (AHJ). Flag for review