Renewable Energy — Texas Master Practice Questions

6 questions · 4% of the NEC Knowledge exam

Worked questions

1. A PV system with a rated output of 5 kW is installed on a residential property. The PV array is connected to a single-phase, 120/240V service. What is the minimum conductor size required for the PV array branch circuit, according to 2026 NEC Article 690.31(A)?

A8 AWG
10 AWG
C12 AWG
D14 AWG

Exam tip

Always check the rated output and the specific requirements for the conductor size in the NEC.

Why B is correct

According to 2026 NEC Article 690.31(A), the minimum conductor size for a PV array branch circuit is 10 AWG for systems with a rated output of less than 10 kW. Options a, c, and d are not the correct minimum conductor size for this scenario.

2. A residential addition requires the installation of a geothermal heating and cooling system. The system includes an outdoor unit and an indoor unit. What is the minimum size of the disconnect required for the outdoor unit, according to 2026 NEC Article 440.9(A)?

A100A
B150A
200A
D250A

Exam tip

Be aware of the specific requirements for disconnects in geothermal systems as outlined in the NEC.

Why C is correct

According to 2026 NEC Article 440.9(A), the minimum size of the disconnect required for an outdoor unit of a geothermal heating and cooling system is 200A. Options a, b, and d are not the correct minimum size for this application.

3. A small-scale hydroelectric plant has a generator with a rated output of 50 kW. The generator is connected to a single-phase, 120/240V service. What is the minimum conductor size required for the generator branch circuit, according to 2026 NEC Article 690.31(A)?

A6 AWG
8 AWG
C10 AWG
D12 AWG

Exam tip

Always check the rated output and the specific requirements for the conductor size in the NEC.

Why B is correct

According to 2026 NEC Article 690.31(A), the minimum conductor size for a generator branch circuit is 8 AWG for systems with a rated output of less than 100 kW. Options a, c, and d are not the correct minimum conductor size for this scenario.

4. 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.

5. A wind turbine generator with a rated output of 10 kW is installed on a rural property. The turbine is connected to a single-phase, 120/240V service. What is the minimum conductor size required for the turbine branch circuit, according to 2026 NEC Article 690.31(A)?

A10 AWG
B12 AWG
C14 AWG
16 AWG

Exam tip

Always check the rated output and the specific requirements for the conductor size in the NEC.

Why D is correct

According to 2026 NEC Article 690.31(A), the minimum conductor size for a wind turbine generator branch circuit is 16 AWG for systems with a rated output of less than 10 kW. Options a, b, and c are not the correct minimum conductor size for this scenario.

6. An industrial facility has a solar water heating system with a storage tank volume of 1000 gallons. What is the minimum size of the overfill vent required for the storage tank, according to 2026 NEC Article 490.31(A)?

A3/4 inch
B1 inch
C1 1/4 inch
1 1/2 inch

Exam tip

Always refer to the specific volume requirements for overfill vents in the NEC.

Why D 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 1000 gallons is 1 1/2 inch. Options a, b, and c are smaller than the minimum required for this tank size.

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Renewable Energy — Texas Master Practice Questions

Worked questions

1. A PV system with a rated output of 5 kW is installed on a residential property. The PV array is connected to a single-phase, 120/240V service. What is the minimum conductor size required for the PV array branch circuit, according to 2026 NEC Article 690.31(A)?

2. A residential addition requires the installation of a geothermal heating and cooling system. The system includes an outdoor unit and an indoor unit. What is the minimum size of the disconnect required for the outdoor unit, according to 2026 NEC Article 440.9(A)?

3. A small-scale hydroelectric plant has a generator with a rated output of 50 kW. The generator is connected to a single-phase, 120/240V service. What is the minimum conductor size required for the generator branch circuit, according to 2026 NEC Article 690.31(A)?

4. 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)?

5. A wind turbine generator with a rated output of 10 kW is installed on a rural property. The turbine is connected to a single-phase, 120/240V service. What is the minimum conductor size required for the turbine branch circuit, according to 2026 NEC Article 690.31(A)?

6. An industrial facility has a solar water heating system with a storage tank volume of 1000 gallons. What is the minimum size of the overfill vent required for the storage tank, according to 2026 NEC Article 490.31(A)?

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