358.10 Uses Permitted.

In the 2023 NEC, Section 358.10(A)(1) was revised to specifically allow EMT in direct burial applications with fittings identified for direct burial.
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In the 2023 NEC, Section 358.10(A)(1) was revised to specifically allow EMT in direct burial applications with fittings identified for direct burial.

Code Change Summary: The permitted use of Electrical Metallic Tubing (EMT) has been revised.

EMT has been allowed “in direct contact with the earth” for many code cycles in Article 358. Direct contact with the earth means touching the earth which is different than being buried in the earth.

In the 2023 NEC®, Section 358.10(A)(1) was revised to specifically allow EMT in concrete, in direct contact with the earth, in direct burial applications with fittings identified for direct burial, or in areas subject to severe corrosive influences where installed in accordance with 358.10(B).

Some installers not familiar with the local soil conditions may still prefer to use nonmetallic wiring methods underground in order to avoid potential service calls from EMT corroding underground or where it emerges from grade.

NEC Table 300.5(A) provides minimum cover requirements for direct-buried cables, conduits, or other raceways installed underground. In the 2023 NEC®, Electrical Metallic Tubing was added to column 3 of Table 300.5(A).

During the 2023 NEC® development process, justification to add EMT to Table 300.5(A) and to modify Section 358.10(A)(1) was heavily reliant on the UL Guide Info for product category FJMX which covers EMT.

Both CMP-3 and CMP-8 made mention of the language in UL product category FJMX in their committee statements regarding the UL Directory recognizing the use of EMT for direct burial applications. Recognizing is different than approving. At the time of the code development process, the UL Guide Info for EMT didn’t actually specify that EMT is suitable for direct burial, it simply stated the following:

Where galvanized steel EMT without supplementary corrosion protection extends directly from concrete encasement to soil burial, severe corrosive effects are likely to occur on the metal in contact with the soil.

The above UL Guide Info statement didn’t recognize EMT as suitable for direct burial, it simply recognized a potential problem.

Another potential problem for the revised code language is that at the time of the code development process, there were no listed EMT fittings identified for direct burial available for purchase. UL Product category FKAV covers EMT fittings and how they are required to be marked based on their suitability. The UL Guide Info for UL product category code FKAV mentions how EMT fittings, or the cartons they are shipped in are required to be marked when they are suitable for wet locations or poured concrete but makes no mention of how EMT fittings are supposed to be marked if they are compliant with the revised language in 358.10(A)(1) and found suitable for direct burial applications.

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:

358.10 Uses Permitted.

(A) Exposed and Concealed. The use of EMT shall be permitted for both exposed and concealed work for the following:

(1) In concrete, in direct contact with the earth or in areas subject to severe corrosive influences where installed in accordance with 358.10(B)

2023 Code Language:

358.10 Uses Permitted.

(A) Exposed and Concealed. The use of EMT shall be permitted for both exposed and concealed work for the following:

(1) In concrete, in direct contact with the earth, in direct burial applications with fittings identified for direct burial, or in areas subject to severe corrosive influences where installed in accordance with 358.10(B)

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358.10 Uses Permitted.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is true?

A: EMT is NOT permitted for underground use.
B: In the 2023 NEC, Section 358.10(A)(1) was revised to specifically allow EMT in direct burial applications with fittings identified for direct burial.
C: EMT is NOT permitted to enclose underground conductors.
D: EMT is NOT permitted above ground.
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