ICC Residential Electrical Inspectors Practice Exam

What is the maximum percent of unbalanced load considered for a feeder neutral load in certain electric appliances?

1. 60%

2. 70%

3. 80%

4. 50%

The correct answer is: 70%

The maximum percent of unbalanced load considered for a feeder neutral load in certain electric appliances is set at 70%. This figure reflects an established guideline that ensures safety and functionality in the electrical system. The rationale behind this specific percentage is to manage the potential for overheating and to safeguard against excessive current that can occur due to unbalanced loads. In practical terms, unbalanced loads arise when the current distribution among the phases of a three-phase system is unequal. If the neutral conductor is not adequately sized to accommodate the unbalanced load, it can lead to increased resistance and heating, posing risks of failure or fires. Consequently, a 70% threshold on the unbalanced load is deemed safe and reliable for most residential applications and adheres to the National Electrical Code standards, which are pivotal for maintaining quality electrical installations and preventing hazards. This assessment helps electrical professionals make informed decisions when designing and implementing electrical systems, ensuring they meet safety requirements while providing efficient operation.