What is the required EMT size for an installation involving four 12 AWG and four 10 AWG THHN copper conductors?

To determine the required EMT (Electrical Metallic Tubing) size for the installation involving four 12 AWG and four 10 AWG THHN copper conductors, it's important to understand the concept of conduit fill.

According to the National Electrical Code (NEC), you must account for the total number of conductors and their sizes when selecting the correct conduit size. In this scenario, you have a total of eight conductors: four 12 AWG and four 10 AWG. Different sizes of conductors require different fill allowances, and the code provides guidelines on the maximum number of conductors allowed in a given conduit size based on their diameter.

For THHN conductors, the diameter of 12 AWG is approximately 0.205 inches, and for 10 AWG, it's around 0.26 inches. Using the NEC's fill table, you would calculate the total area needed for the given conductors and compare it to the area of the available EMT sizes.

Conduit sizing must also account for a percentage fill that can’t exceed 40% for more than two conductors, and a larger size will likely be needed when multiple conductors are used. After inappropriate options are considered, the proper conduit size that accommodates the