New York State Master Electrician Practice Exam

What is typically not listed on a motor disconnect switch?

1. Voltage rating

2. Power conductor size

3. Laboratory approval

4. Disconnecting means

The correct answer is: Laboratory approval

The correct choice is that typically, the laboratory approval is not listed on a motor disconnect switch. Disconnect switches are designed to provide a clear and safe means of disconnecting a motor from its power supply for maintenance and safety purposes. The voltage rating is essential for ensuring that the disconnect switch can handle the specific voltage used by the motor, which is why it is prominently included on the switch. Additionally, the power conductor size is often specified, as it informs the user of the appropriate conductor gauge to use with the switch to ensure safe and efficient operation. The disconnecting means is also clearly marked, reflecting the switch's function in cutting the electrical supply. In contrast, laboratory approval, while relevant in the context of overall safety and compliance standards for electrical equipment, is usually not a specific detail listed on a disconnect switch itself. Instead, such certifications would typically be documented elsewhere, such as in product literature or compliance ratings, rather than directly marked on the equipment.