NEC Commercial Electrical Practice Test

The sum of the cross-sectional areas of all the contained conductors in an auxiliary gutter shall be a maximum of what percent of the interior cross-sectional area of the gutter?

1. 10%

2. 15%

3. 20%

4. 25%

The correct answer is: 20%

The maximum allowable sum of the cross-sectional areas of all the contained conductors in an auxiliary gutter is specified to be 20% of the interior cross-sectional area of the gutter. This regulation is in place to ensure adequate space for air circulation and to minimize overheating, which can occur when conductors are densely packed. Providing a sufficient percentage of free space within the gutter helps maintain proper thermal management, preventing damage to insulation and reducing the risk of electrical faults due to overheating. The choice of 20% strikes a balance between maximizing the amount of conductors that can be accommodated while also ensuring safety and reliability in the electrical system. This regulation is part of the NEC guidelines designed to promote safe electrical installations, and adherence to these standards is critical for maintaining performance and safety in electrical systems.