Where should surge-protective devices be located in dwelling units and similar facilities?

Surge-protective devices (SPDs) should be located in or adjacent to distribution equipment or connected to the load side of the feeder to provide maximum protection against transient voltage surges. This position allows the SPD to effectively intercept and mitigate surges before they reach sensitive electrical equipment and devices throughout the dwelling unit. By being close to the main electrical distribution panel or service equipment, the SPD can operate more efficiently and minimize the length of the wiring run, which would otherwise increase the likelihood of surges impacting the system.

Additionally, this strategic positioning complies with the National Electrical Code (NEC) requirements, ensuring that all electrical wiring and devices remain safe and secure from potential voltage spikes. SPDs located within distribution or connected to feeders help protect against disturbances caused by nearby lightning strikes, utility grid surges, and other sudden increases in voltage.

Locating SPDs in areas such as the garage, near the front door, or in the attic may not provide optimal protection due to their distance from the main distribution panel. Such placements can expose connected equipment to potential surges for longer periods before the SPD can respond effectively, thus diminishing its protective function. Therefore, the best practice aligns with placing SPDs in relation to the main electrical distribution system.