250.64(G) Enclosures with Ventilation Openings.
Code Change Summary: New code section on the routing of grounding electrode conductors through equipment with ventilation openings.
New Section 250.64(G) in the 2023 NEC®, was added to ensure that grounding electrode conductors are not installed through equipment ventilation openings which can compromise air flow. A reduction in air flow and proper ventilation can result in equipment overheating.
Many enclosures have ventilation openings. Dry type transformers for example typically have a perforated metal bottom that allows air flow. It is very common to see grounding electrode conductors routed through the ventilation openings as they make their way to the building grounding electrode system as required in Section 250.30(A)(4). This practice is no longer permitted.
Electricians will need to route grounding electrode conductors (GEC’s) through transformer enclosures and other enclosures without running the GEC through the ventilation openings.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2023 NEC® edition of NFPA 70.
2020 Code Language:
This code section did not exist.
2023 Code Language:
N 250.64(G) Enclosures with Ventilation Openings. Grounding electrode conductors shall not be installed through a ventilation opening of an enclosure.