Code Explained

Whole-Home Surge Protection and NEC 230.67

Since the 2020 NEC, new and replaced dwelling services need a surge protective device. Here is what it does, what changed in 2023, and what it doesn’t do.

By IES team, Innovative Electrical Services (IES), Auburn, CA · Reviewed November 2026 · 2 min read

Key takeaways
  • A surge protective device (SPD) limits brief voltage spikes by sending surge energy to ground.
  • NEC 230.67 requires a Type 1 or Type 2 SPD for services that supply dwelling units.
  • It applies to new services and to service equipment that is replaced.
  • The 2023 NEC added a 10 kA minimum nominal discharge rating and more occupancy types.

A surge is a very short spike in voltage, lasting millionths to thousandths of a second. Some come from outside (utility switching, nearby lightning), and many come from inside the home when large motors start and stop. Modern homes are full of electronics, from furnace boards to appliance controls and EV chargers, and those are what surges damage.

utility surgemeterService panelSPDto groundprotected circuitsType 1 or Type 2, rated 10 kA or more
A whole-home surge protective device (SPD) sits at or next to the service equipment and sends surge energy to ground before it spreads through the house.

What an SPD does

A surge protective device sits across the circuit and does nothing at normal voltage. When voltage spikes, it clamps the spike and diverts the extra energy to the grounding system. A whole-home SPD at the panel handles large surges arriving on the service, and point-of-use strips can catch smaller ones close to sensitive equipment. They work well together.

What NEC 230.67 requires

Paraphrasing the section:

  • Services that supply dwelling units must have surge protection (added in the 2020 NEC).
  • The SPD must be an integral part of the service equipment or located right next to it. The 2023 edition also allows it at the next level of distribution equipment downstream.
  • It must be a Type 1 or Type 2 device.
  • When service equipment is replaced, the requirement applies as well.
  • The 2023 NEC added dormitory units, guest rooms and suites of hotels and motels, and patient sleeping rooms of nursing homes and limited-care facilities, and set a minimum nominal discharge current rating of 10 kA.

Type 1 vs Type 2

Type 1 SPDs are designed to be installed on either side of the service disconnect, including the line side. Type 2 SPDs go on the load side of the service disconnect, typically as a breaker-style device or a small box beside the panel. Both satisfy 230.67.

What an SPD doesn’t do

  • It won’t save equipment from a direct lightning strike to the house.
  • It doesn’t fix sags, outages or a loose utility neutral.
  • It wears with use. Most have an indicator light; check it now and then and replace the device when it says so.
  • It relies on a good grounding and bonding system. Short, straight leads make it work better.

Sources and further reading

  1. Leviton, NEC code requirements for surge protection
  2. NAHB, 2023 National Electrical Code adoption kit
  3. NFPA 70, National Electrical Code, 2023 edition (free read-only access)

Local rules decide. These articles explain general ideas and point to the code sections we use. They are not legal or engineering advice and don’t replace the code itself. California adopts the NEC with its own amendments, cities and counties can add more, and the local inspector (the AHJ, or authority having jurisdiction) has the final say on any job. Read the code free at NFPA’s free access page.