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NEC 300.6 Protection Against Corrosion. NFPA 70 2023

jar546

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What the code reads:

300.6(A)(3) In Concrete or in Direct Contact with the Earth.
Ferrous metal raceways, cable armor, boxes, cable sheathing, cabinets, enclosures (other than surrounding fences and walls), elbows, couplings, nipples, fittings, supports, and support hardware shall be permitted to be installed in concrete, in direct contact with the earth, or in areas subject to severe corrosive influences where made of material approved for the condition or where provided with corrosion protection approved for the condition.

What it means:

Metal raceways installed in the earth can be coated with an asphalt compound, plastic sheath, or other equivalent protection to help prevent deterioration. Also, metal raceways are available with a bonded PVC coating. Galvanized steel RMC and steel IMC generally do not require supplementary corrosion protection.
 
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