Whole-home surge protection

The rule

NEC section 230.67 says all services supplying dwelling units must have a surge protective device (SPD). Three details decide most real jobs:

• Type. The device must be Type 1 or Type 2. Both are hardwired into the electrical system. Plug-in strips do not count.
• Location. The SPD is part of the service equipment or sits immediately adjacent to it. An exception lets it go at the next downstream distribution equipment instead.
• When it applies. It covers new services and replaced service equipment. The 2023 NEC text, as summarized by IAEI Magazine, applies it to all services and replacements of service equipment.

A home with an older panel that is not being replaced does not trigger the rule. But a panel swap does, which is why a 200 amp panel upgrade includes one.

Which code edition applies

Check the edition, because both of these are true on the same day.

2022 California Electrical Code. Based on the 2020 NEC, it put 230.67 into force in California on January 1, 2023, along with the outdoor emergency disconnect in 230.85.

2025 California Electrical Code. Effective January 1, 2026 and based on the 2023 NEC. The 2023 NEC widened 230.67 from dwelling units to also cover dormitory units, hotel and motel guest rooms and suites, and nursing home patient sleeping rooms. For a single-family house nothing about the main requirement changed. A city may adopt local amendments, and a state pause on new residential building standards is in effect (AB 130), so ask your building department if you have a question about a specific rule.

The section numbers here follow the NEC and the 2022 California memo above, so confirm the 2025 California wording with your building department.

What a whole-home device does

Voltage spikes come from the utility grid, from nearby lightning and from large motors switching inside the house, such as an air conditioner compressor. A panel-mounted SPD gives the spike a path to ground before it spreads through the wiring. It reduces the stress on televisions, computers, appliance boards, EV chargers and heat pumps.

It does not stop everything. It cannot promise to survive a direct strike, and it does not clean up voltage that stays high or low for long periods. Pair it with point-of-use strips for sensitive gear if you want a second stage.

Type 1 or Type 2

	Type 1	Type 2
Where	Ahead of the main breaker, at the service entrance	After the main breaker, at the panel
Protects against	External surges and lightning	Internal surges and indirect lightning

Some new panels come with the SPD built in. For others, the electrician adds a stand-alone unit next to the panel and wires it to a breaker. Your electrician picks the type, and the inspector checks the label.

Cost

The typical SoCal range for a panel-mounted device, installed, is $200 to $800 as of October 2026. That figure is from Angi’s HomeAdvisor-sourced page, and a different Angi article shows $70 to $700, so quotes vary. The price rises with the device rating, with a hard-to-reach panel, and with a panel that needs a new breaker space. When the SPD comes with a panel swap, it is part of the job. See the surge protector cost page and the panel upgrade cost page.

Adding one to an older panel

Nothing in 230.67 forces you to add one to a panel that stays in place. It is still a reasonable add-on, especially in homes with a heat pump, an EV charger, a home office or a lot of electronics. The electrician checks that the panel has room, that the grounding is in good shape, and that the device has a rating that fits your service. A device that sits next to a Zinsco or Federal Pacific panel does not fix those panels, since replacing the panel is the usual advice.

During a panel upgrade

If you are replacing the panel, ask whether the quote lists a Type 1 or Type 2 SPD by name. The inspector expects to see it. The permit and inspection page covers the other checks, and the 2025 code changes guide lists the rest of what changed.

Reading the status light

Most devices show a green light when protection is active. A red or dark light means the protection modules have worn out or the unit lost power, and the device needs replacing. Check it after storms, and note its location when you read your panel with the panel reading guide.