Oklahoma Electrical Practice Exam

What is the smallest allowable depth for direct burial cable operating at 600v or less?

1. 12 inches

2. 18 inches

3. 24 inches

4. 30 inches

The correct answer is: 24 inches

The correct choice for the smallest allowable depth for direct burial cable operating at 600 volts or less is based on the National Electrical Code (NEC) standards. According to NEC Article 300.5, the minimum burial depth for direct burial cables, such as those rated for 600 volts or less, is 24 inches when the cables are being buried without any additional protection or conduit. This minimum depth is required to provide protection against potential damage from surface activity and environmental factors. Burial at this depth ensures that the cables are less likely to be accidentally disturbed by activities such as gardening, landscape work, or other excavation activities, thereby reducing the risk of electrical hazards. In terms of construction practices, establishing a minimum depth of 24 inches also takes into consideration frost lines and the potential for settling, helping to maintain the integrity of the installation over time. By adhering to these guidelines, electricians ensure that the system remains safe and operable under various conditions.