A solar thermal system is installed on the roof of a commercial building. The system includes a storage tank with a volume of 500 gallons. What is the minimum size of the overfill vent required, according to 2026 NEC Article 490.31(A)?
- A1/2 inch
- B3/4 inch
- 1 inch
- D1 1/4 inch
Exam tip
Be aware of the specific requirements for overfill vents based on the volume of the storage tank.
Why C is correct
According to 2026 NEC Article 490.31(A), the minimum size of the overfill vent for a storage tank with a volume of 500 gallons is 1 inch. Options a, b, and d are larger than the minimum required for this tank size.