What is the minimum size EMT required for the installation of eight 12 AWG THW copper current-carrying conductors and one 12 AWG THW copper equipment grounding conductor?

In order to determine the minimum size of Electrical Metallic Tubing (EMT) required for the installation of multiple conductors, we need to refer to the National Electrical Code (NEC) guidelines regarding conduit fill.

According to NEC Article 314, when calculating the conduit fill for circular conductors, you sum the area of all conductors and compare that against the allowable fill percentages based on the size of the conduit. For EMT, there are standards that specify the maximum number of conductors allowed in a given diameter of conduit.

For the task of housing eight 12 AWG THW copper conductors and one 12 AWG copper equipment grounding conductor, we first need to calculate the total cross-sectional area of these conductors. Each 12 AWG copper wire has a specific cross-sectional area, and by summing the areas of all nine conductors, we can then determine the required conduit size.

When this calculation is performed, it becomes evident that a 3/4" EMT can accommodate a sufficient number of current-carrying conductors—the eight 12 AWG wires along with the additional equipment grounding conductor—while still adhering to the NEC's fill requirements.

Choosing a conduit size that is too small could lead to overheating