Oklahoma Electrical Practice Exam

What requirement must an underwater junction box for a 12-volt lighting system meet according to NEC?

1. It must be made from aluminum

2. It must be filled with a potting compound

3. It must be above water level

4. It must be accessible for maintenance

The correct answer is: It must be filled with a potting compound

The requirement for an underwater junction box, particularly for a 12-volt lighting system, to be filled with a potting compound is rooted in the need for moisture protection and electrical insulation. The National Electrical Code (NEC) emphasizes the importance of safeguarding electrical connections from water intrusion. Filling the junction box with a potting compound creates a barrier that prevents water from reaching the electrical components, thereby reducing the risk of short circuits and potential failure of the system. Using a potting compound also enhances the durability of the junction box by protecting it from environmental elements and corrosion, which is crucial for underwater applications. This makes the junction box safer and more reliable, ensuring that the lighting system operates effectively without the risk posed by moisture.