Master Electrician Practice Exam

In a commercial setting, what is the typical primary voltage for a transformer?

1. 120 volts

2. 208 volts

3. 277 volts

4. 480 volts

The correct answer is: 480 volts

In a commercial setting, the typical primary voltage for a transformer is 480 volts. This voltage level is commonly used for three-phase electrical systems that power larger equipment and machinery. The use of 480 volts helps to reduce the current flow required for a given power demand, which is advantageous for minimizing voltage drop across conductors and for increasing the efficiency of the electrical distribution system. Transformers are utilized to step down this voltage to usable levels for different types of equipment and lighting within commercial buildings. While other voltage levels like 120 volts, 208 volts, and 277 volts are also used in commercial applications, they are generally secondary voltages or used in specific scenarios, such as for lighting or smaller appliances. Thus, the 480 volts is a standard for many commercial applications because it balances performance and efficiency when powering robust equipment.