Which statement is true regarding SPD components?

The statement regarding SPD (Surge Protective Device) components being accessible for periodic inspections is correct. Accessibility is crucial for ensuring that SPDs are properly maintained and evaluated for their effectiveness. Periodic inspections can help identify any degradation or failure in the device, which might prevent it from performing effectively during a surge event. Ensuring that SPDs can be easily accessed means that maintenance personnel can routinely check their condition, verify any visual indicators, and replace them when necessary, thus maintaining the integrity of the lightning protection system.

In contrast, while SPDs might be installed in enclosed spaces for practicality, stating they must be concealed for safety overlooks the importance of routine access for maintenance. Additionally, SPDs must be installed following specific guidelines to ensure their effectiveness and compliance with safety standards; neglecting this could lead to improper operation. Lastly, saying that SPDs are designed for permanent installation only does not take into account the necessity for replacement or maintenance, which could be considered a temporary removal or adjustment during inspections.