Journeyman Electrician Practice Exam

An installation of 40 feet of electrical metallic tubing (EMT) will contain various sizes of conductors. What is the minimum trade size EMT required for this installation?

1. 1 inch

2. 1 1/4 inch

3. 1 1/2 inch

4. 2 inch

The correct answer is: 1 1/2 inch

To determine the minimum trade size of electrical metallic tubing (EMT) required for an installation containing various sizes of conductors, it's important to consider conduit fill requirements set forth in the National Electrical Code (NEC). The NEC provides specific tables that outline the maximum numbers of conductors allowed in various sizes of conduit based on conductor gauge and insulation type. For any given installation, the total number and size of the conductors must be calculated to ensure they fit within the selected conduit without exceeding the fill limitations. The NEC has established that for common given conductor types, a certain size of EMT may be required to accommodate 40 feet of conductors without exceeding the maximum fill percentage. Choosing a conduit size that allows for adequate space for the conductors minimizes risks related to overheating and ensures that installation meets safety standards. The selected size should also allow for possible future additions of conductors, which is why using a larger conduit than absolutely necessary is often recommended. In this case, the choice of 1 1/2 inch EMT is typically justified when the installation includes a combination of multiple conductors of varying sizes. This larger size ensures sufficient space for conductor fill, thus adhering to the safety standards and maintaining the integrity of the electrical installation.