Quick Answer
Rapid shutdown is required for detached structures when the electrical system is connected to a photovoltaic (PV) array that exceeds 1,000 volts and is installed in a detached structure that is not part of a dwelling unit, such as a detached garage, shed, or outbuilding. --- Definition and Requirements Rapid shutdown is a safety feature that rapidly reduces the DC voltage of a PV array to a safe level, typically 30 volts or less, in the event of an emergency or during maintenance. This feature is mandated by the National Electric Code (NEC) in the United States for PV systems installed in detached structures that are not part of a dwelling unit and have a DC voltage rating of 1,000 volts or more. According to the NEC 690.12, rapid shutdown is required for PV systems installed in detached structures, including garages, sheds, and outbuildings, unless the system is designed and installed to meet the NEC 690.12 exception for systems with a DC voltage rating of 1,000 volts or more.
Installation and Testing Requirements
To ensure compliance with the NEC, rapid shutdown devices must be installed in accordance with the manufacturer’s instructions and the NEC. The devices must be installed between the PV array and the electrical panel and must be capable of reducing the DC voltage to a safe level within 30 seconds or less. Additionally, the devices must be marked with their certified ratings and must be listed by a recognized testing laboratory, such as UL or ETL. After installation, the rapid shutdown devices must be tested to ensure they are functioning properly and are reducing the DC voltage to a safe level within the required time frame.
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