National Electrical Installation Standards

Standards as High as Your Own

Monday, April 20, 2020


Good morning,

Re: 2017 NEC Article 250.120(B)

Can I get your interpretation on the last sentence of Article 250.120(B). It states that "aluminum or copper clad aluminum conductors shall not be terminated within 18" of the earth". In freestanding service equipment, the ground buss is located well below the 18" requirement and this equipment is UL listed. My interpretation is if the equipment is placed on an equipment pad then there is no NEC violation. Can you please provide an explanation.

Thank you,

Ed Tait Jr



Greetings Ed and Thanks for the question. You're in luck. The 2020 NEC was revised in Section 250.120(B)(2) to permit connections of aluminum and copper-clad aluminum conductors within 18 inches of the earth where they are located within equipment that is listed and identified for the location. Based on the information in the question, your installation, which is a fairly common practice, will be acceptable. 

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