National Electrical Installation Standards

Standards as High as Your Own

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Monday, January 17, 2022

Question:

Hello Code Question,

In a place of assembly, when we exit the concrete slab and enter into the bottom of panel cans can that 24-30” piece of conduit remain PVC, or must we changeover to EMT at the slab? The panels are inside the building.

Gary Weber

A

Answer:

Greetings Gary,

Section 518.4(A) addresses the required wiring methods for places of assembly. It indicates that the fixed wiring methods shall be metal raceways, flexible metal raceways, nonmetallic raceways encased in not less than 50 mm (2 in.) of concrete, Type MI, MC, or AC cable. The wiring method shall itself qualify as an equipment grounding conductor according to 250.118 or shall contain an insulated equipment grounding conductor sized in accordance with Table 250.122. Based on the information in the question, the EMT would be required for emerging from the slab as long as the PVC remains outside the building. There is the option of concrete encasement, which is not always practical. Section 518.4(B) indicates that In addition to the wiring methods of 518.4(A), nonmetallic-sheathed cable, Type AC cable, electrical nonmetallic tubing, and rigid nonmetallic conduit shall be permitted to be installed in those buildings or portions thereof that are not required to be of fire-rated construction by the applicable building code. So it could depend on where the panelboards are located. It is a good idea to verify this with the AHJ.

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