HOLT Electricians Practice Exam

What aspect of the equipment must be complied with when selecting the actual conductor size for a motor feed?

1. Voltage rating

2. Power factor

3. Terminal temperature rating

4. Installation environment

The correct answer is: Terminal temperature rating

When selecting the actual conductor size for a motor feed, it is essential to comply with the terminal temperature rating of the equipment. The terminal temperature rating indicates the maximum allowable temperature at which the terminals of the equipment can operate safely without risk of damage. If conductors are undersized, they can overheat, leading to potential insulation breakdown or failure, which can cause shorts, fire hazards, or system failures. Choosing the correct conductor size ensures that the current flowing through the wires will not exceed the temperature limits specified for the terminals. This safety factor is critical, especially in motors, which can draw significantly higher current during startup (inrush current) compared to their running condition. Therefore, adhering to the terminal temperature rating safeguards the integrity of both the motor and the wiring system, promoting reliable operation and longevity. While factors like voltage rating, power factor, and installation environment are important considerations in selecting conductors, they do not directly influence the safe temperature operation of the terminal connections as the terminal temperature rating does.