What size Electrical Metallic Tubing is required for a 12/3 NM Cable with a width of 524 mils and height of 190 mils?

To determine the appropriate size of Electrical Metallic Tubing (EMT) for a 12/3 NM cable, we need to calculate the required fill based on the dimensions of the cable—its width of 524 mils (0.524 inches) and height of 190 mils (0.190 inches).

The NEC (National Electrical Code) mandates that conduits have certain fill limits to ensure safety and functionality. For one cable, the maximum fill is typically 53% of the conduit’s cross-sectional area. To select the correct EMT size, we first need to calculate the area of the NM cable. The total cross-sectional area can be approximated by multiplying the width by the height:

• Area = Width x Height

• Area = 0.524 inches x 0.190 inches = 0.09956 square inches

Next, we refer to the NEC tables for the cross-sectional areas of different sizes of EMT. A 3/4" EMT conduit has a cross-sectional area of approximately 0.301 square inches.

Calculating 53% of that area gives us:

• 0.301 in² x 0.53 = 0.15953 in²

Since the area of our