What is the definition of a surge arrest according to the National Electrical Code (NEC)?

The correct definition of a surge arrest, according to the National Electrical Code (NEC), is that it is a device designed to limit surge voltages by discharging surge current to ground while being capable of repeating this function as necessary. This means that the surge arrestor is specifically engineered to respond to high-voltage spikes, such as those caused by lightning or switching surges, by diverting the excessive voltage to the ground. This action helps protect electrical equipment from damage caused by these transient surges.

This ability to discharge current to ground and reset for future events is crucial in maintaining the functionality and longevity of electrical systems. When a surge occurs, the surge arrestor operates quickly to ensure that the voltage does not exceed a specified threshold, thus safeguarding connected devices.

The other options, while referring to surge-related concepts, do not accurately describe the operational characteristics and primary purpose of a surge arrestor as outlined by the NEC. For instance, a device that merely stores surge current or creates airdrops does not encompass the direct function of discharging voltage to ground, which is an essential aspect of how surge arrestors work.