Definition
A panel-mounted device (SPD) that clamps voltage spikes from grid switching, storms, and large motors before they reach your electronics — required on new panels by the 2023 NEC.
Don't power strips already do this?
Only for what's plugged into them, and only until their small clamping element wears out — silently. A whole-home surge protective device mounts at the panel and clamps the spike where it enters, protecting hardwired equipment strips can never reach: the heat pump, the induction range, the water heater's electronics, every LED driver and GFCI in the house. Strips then become a second layer, not the only one.
Where do damaging surges actually come from?
Mostly from inside and nearby, not lightning: utility grid switching, transformers re-energizing after an outage, and your own large motors cycling. The Puget Sound pattern that kills electronics is the windstorm outage-and-restore cycle — power flickering back on is a spike event, repeated every storm season. Homes with generators or battery backup see extra transfer events on top.
What does installation involve and what does it cost?
A Type 2 SPD lands in or beside the panel on a dedicated breaker — about an hour of licensed work when panel space exists, commonly a few hundred dollars installed, device included. Since the 2023 NEC requires surge protection on panel replacements anyway, pairing it with any planned panel work makes it nearly free to add. Look for a status indicator and replace the module after a major event.
In the Puget Sound
November-through-February windstorms make outage-restore cycles routine across Puget Sound — each restore is a surge event, which is why SPDs earn their keep here faster than in calmer grids.
Related terms
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Trade: Electrical