Whole-house surge protection at the service
Services supplying homes, dorm units, hotel and motel guest rooms, and certain nursing-home sleeping rooms need a Type 1 or Type 2 surge-protective device at or next to the service equipment, rated at least 10 kA.
What the code requires
A surge-protective device (SPD) is required on services that supply dwelling units, dormitory units, hotel and motel guest rooms and suites, and nursing-home and limited-care areas used only as patient sleeping rooms.
The SPD must be part of the service equipment or installed immediately next to it. It must be a Type 1 or Type 2 device, and its nominal discharge current rating (In) must be at least 10 kA.
When service equipment is replaced, all of 230.67 applies. That means replacing the service equipment on an existing home brings in the SPD requirement.
On the job
- Replacing service equipment without adding an SPD is a common correction.
- A Type 3 point-of-use device does not satisfy this rule.
- An SPD rated below 10 kA nominal discharge current (In) does not meet the 2023 rule.
Exceptions that matter
- The SPD may instead be installed at each next-level distribution equipment downstream toward the load, such as the interior panelboard fed by an exterior meter-main. If the service feeds more than one such piece of equipment, each one needs its own SPD.
What changed in 2023
The 2023 code expanded the rule from dwelling units only to dorms, hotel and motel rooms and nursing-home sleeping rooms, added the 10 kA minimum rating, and added companion rules for feeders (215.18) and outside feeders (225.42).
Related sections
- NEC 215.18
- NEC 225.42
- NEC 230.82
- NEC 242.9
Where this comes from
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