Choosing a whole-house surge protector: do not shop by the biggest kA number

Compare the application before comparing kA

A homeowner asking whether a surge protector was correctly installed pointed to its green indicator as possible proof. A brand name, indicator light or large surge-current number does not establish a suitable installation. Begin with the electrical system, the device’s intended location, applicable listing and instructions, and a practical way to verify its condition after installation.

Source: Is my surge protector correctly installed?

Read five separate ratings before comparing surge capacity

UL 1449 Type 1 and Type 2 identify permitted application categories. A listed Type 1 device can be used in permitted supply-side or load-side locations; Type 2 is for the load side of the service overcurrent device. The selected model’s instructions still control its supported connection and any required protection. Type is not a quality ranking.

Voltage protection rating, or VPR, reports limiting performance under a defined test. Maximum continuous operating voltage, or MCOV, concerns the continuous voltage applied to a protection mode. Nominal discharge current, In, is an impulse-test rating. Short-circuit current rating, SCCR, concerns fault-current suitability. These are different from the advertised maximum surge-current capacity and must not be added into one score.

Source: Surge protection FAQ | Eaton · Eaton: surge protection frequently asked questions

The mounting route changes the installed result

Illustrative scenario: two proposals offer different surge-current ratings. The higher-rated unit requires a less favorable mounting route in the existing equipment arrangement, while the other can be installed as intended with a more direct connection. That does not automatically make the smaller unit better; it means the complete installation must be evaluated. The quote should explain the selected model and location rather than using the advertised number as the sole justification.

Ask for the exact product and supported connection

Ask the electrician to identify the exact product, compatible system configuration, intended installation type and location, protective-device requirements, and indicator visibility. Keep the work within the manufacturer's instructions and applicable local requirements. Owners should not infer compatibility from a similar-looking breaker or attempt to share terminals because another forum user reported doing so. Internal connection details are professional design and installation decisions.

Compare installed scope and monitoring

Compare total scope: equipment, installation labor, any panel corrections, labeling, inspection requirements, and handoff. An unusually low price may exclude necessary supporting work, while an expensive product does not excuse poor installation. Ask how normal status is demonstrated and what the owner must do when it changes. Keep model and receipt information with the electrical records so a later service provider can identify what was installed.

Accept a documented installation, not a protection promise

The acceptance conversation should be concrete: this model, in this location, on this system, following these instructions, with this status indication and support process. That is more useful than a broad assurance that the whole house is now protected from everything. A properly bounded explanation helps the owner compare proposals and maintain the protection after the installer leaves.

Document the code check separately from the marketing rating

The service design should identify the applicable California Electrical Code surge-protection requirement, including §230.67 where relevant, and the permit’s code edition. A 2025 CEC change summary by the Sacramento Valley Association of Building Officials, posted by El Dorado County, identifies a minimum 10 kA nominal discharge current requirement in the surge provisions. That is In, not the larger maximum-surge or short-circuit number on a sales sheet.

Service replacement can make surge protection a permit requirement rather than an optional product purchase. Humboldt County’s 2023 residential service-panel handout expressly includes a Type 1 or Type 2 SPD for replacements and upgrades. Alameda’s May 29, 2025 service-permit handout also lists surge protection under §230.67. These dated local examples are not the complete 2025 CEC. For the proposed replacement or upgrade, have the electrician confirm the requirement with the permitting authority under the permit’s code edition and include it in the scope.

Have the electrician document the provision that applies to the actual service, feeder or replacement scope and the selected product’s compliance. A change-summary sheet is not the complete adopted code, and it does not establish that every existing home needs an immediate retrofit. The purpose of the code check is to prevent a catalog comparison from overlooking a required rating or installation condition.

Source: Sacramento Valley Association of Building Officials: 2025 CEC Significant Changes, hosted by El Dorado County · Humboldt County: building forms, including the service panel replacement handout · City of Alameda: Residential Electrical Services Permit Requirements, revised May 29, 2025

Put it into practice

A decision table to keep handy