Which of these is not a requirement for surge protective devices?

Surge protective devices (SPDs) have several important requirements to ensure their effectiveness and safety in electrical systems. Among these requirements, having adjustable settings is not a mandated necessity.

The necessity of being listed by recognized bodies is critical. This listing ensures that the SPDs have been tested and meet certain performance and safety standards, providing confidence in their usage. Correct installation following the National Electrical Code (NEC) regulations is also vital, as improper installation can lead to failures or hazards, compromising the protection that the devices are designed to offer. Furthermore, a defined operational range is important since it specifies the voltages within which the device can effectively operate and protect connected equipment.

While adjustable settings may offer flexibility in some applications, they are not a fundamental requirement for all surge protective devices. Many SPDs function effectively without such adaptability, focusing instead on providing reliable protection against overvoltage transients.