Master Electrician Exam (NEC)Special Occupancies, Equipment, and ConditionsMedium
A master electrician is installing a fuel cell system as a standalone power source for a remote cabin. The fuel cell system generates DC power, which is then converted to AC by an inverter. Which of the following statements regarding the grounding of the fuel cell system is correct according to NEC Article 692?
- AThe AC output of the inverter does not require grounding if the fuel cell system is isolated from the utility grid.
- BThe fuel cell system's DC output circuits must be grounded in accordance with the requirements of Article 250.
- CA grounding electrode system is not required for a standalone fuel cell system if it has no connection to the earth.
- DThe DC output circuits of the fuel cell system are not required to be grounded if the system is isolated from other AC systems.
Show answer & explanationAnswer & explanation
Correct answer: B. The fuel cell system's DC output circuits must be grounded in accordance with the requirements of Article 250.
NEC 692.41 states that fuel cell system grounding shall be in accordance with Article 250. This means the DC output circuits must be grounded, and a grounding electrode system is required, regardless of whether it's a standalone system or interconnected.
Why the other options are wrong
- A. The AC output of an inverter, even in a standalone system, typically requires grounding to provide a reference point for voltage and a path for fault currents, in accordance with Article 250.
- C. Even standalone systems require a grounding electrode system to provide a safe path for fault currents and stabilize voltage, as specified in Article 250.
- D. NEC 692.41 requires grounding of DC output circuits in accordance with Article 250, making this statement incorrect.
Fuel Cell System Grounding (NEC)
The National Electrical Code (NEC) mandates that fuel cell systems, regardless of being standalone or interconnected, must be grounded in accordance with the general grounding requirements of NEC Article 250 to ensure safety and proper fault protection.
- Grounding per NEC Article 250.
- Applies to DC output circuits and AC output of inverters.
- Ensures fault current path and voltage stabilization.
Memory trick: Fuel Cells: Even if isolated, ground them like everything else, by Article 250.