24.1-06-03-01. (NEC 300) Wiring methods.

In some states, EMT installed in direct contact with the soil requires supplemental corrosion protection such as this pipe wrap.
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In some states, EMT installed in direct contact with the soil requires supplemental corrosion protection such as this pipe wrap.

NEC Section 358.10 allows electrical metallic tubing (EMT) to be used underground. This is a general rule which is often modified or amended by states that are known to have corrosive soil conditions.

According to UL product category FJMX, which covers electrical metallic tubing, “galvanized or stainless steel EMT installed in concrete on grade or above generally requires no supplementary corrosion protection. Galvanized steel EMT in concrete slab below grade level may require supplementary corrosion protection”.

 In North Dakota, the rules on installing EMT underground or in concrete are different. Refer to the Laws, Rules and Wiring Standards of North Dakota for additional rules pertaining to lighting standards.

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24.1-06-03-01. (NEC 300) Wiring methods.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:
In North Dakota, which of the following is true?
A: Electric metallic tubing is permitted where encased in concrete that is embedded in the earth.
B: Electric metallic tubing is permitted in direct contact with earth.
C: Electric metallic tubing shall not be used in direct contact with earth unless supplemental corrosion protection is provided.
D: Electric metallic tubing shall not be used in concrete below grade, in concrete slab or masonry in direct contact with earth.
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