POWER GEAR GUIDE · GENERATOR SAFETY & BUYING GUIDE

Best Generator Interlock Kits: Choose by Exact Panel

Compare OEM and independently listed generator interlock options for compatible Square D, Eaton and other load centers. The best kit is the one documented for your exact electrical panel - not the one with the most reviews.

Panel-specific fitOEM vs aftermarketUL 67 contextElectrician installation

Compare Current Options

Generator interlock kits and compatible electrical panel accessories — Verify the panel label, series and breaker configuration before selecting any interlock.

Affiliate disclosure: As an Amazon Associate, we earn from qualifying purchases.

Editorial methodology

This is a manufacturer-documentation comparison, not a hands-on installation test. We prioritize exact load-center compatibility, mechanical interlocking, documentation and local acceptance over price. Never infer compatibility from brand alone or from a photograph of the breaker layout.

Quick Answer

Choose an OEM Kit First When One Is Approved for Your Exact Panel

For a supported Square D QO or Homeline panel, start with Schneider Electric's documented accessory for that precise load-center model and series. For an Eaton BR panel, use Eaton's catalog-number selection guidance. A listed aftermarket kit may be an option if its documentation matches the exact panel and the local authority having jurisdiction (AHJ) accepts it.

Do not buy until your electrician verifies the fit. An interlock that fails to block simultaneous utility and generator breaker operation can create a lethal backfeed hazard.

Generator Interlock Quick Picks by Panel Family

For supported Square D QO panels

Schneider Electric QO OEM interlock

QO family only. Verify the exact load-center catalog number before ordering.

See Prices Read Review

For supported Square D Homeline panels

Schneider Electric Homeline OEM interlock

Homeline family only. Verify the exact load-center catalog number before ordering.

See Prices Read Review

For compatible Eaton BR load centers

Eaton BR mechanical interlock

Eaton BR family only. Verify the exact load-center catalog number before ordering.

See Prices Read Review

Documented third-party QO option

Westinghouse WLock QO

Specified QO G/S series only. Verify the exact load-center catalog number before ordering.

See Prices Read Review

Aftermarket alternative where accepted

GenInterlock panel-specific kits

Exact supported panel only. Verify the exact load-center catalog number before ordering.

See Prices Read Review

Generator Interlock Kit Comparison

Option	Documented panel family	Critical verification
Schneider Electric QO OEM interlock	QO family only	Manufacturer accessory; confirm exact QO load-center catalog number, series, breaker arrangement and approved kit code
Schneider Electric Homeline OEM interlock	Homeline family only	Not interchangeable with QO. Confirm panel series, main breaker location and manufacturer installation sheet
Eaton BR mechanical interlock	Eaton BR family only	Eaton lists multiple BR mechanical interlock kits. Match exact panel catalog and main breaker family; BRMIKBR is not universal
Westinghouse WLock QO	Specified QO G/S series only	Westinghouse limits this kit to certain Square D QO indoor and outdoor series and breaker arrangements. Local approval still required
GenInterlock panel-specific kits	Exact supported panel only	Manufacturer offers panel-specific MET-listed products. Verify the exact SKU, independent listing documentation, and AHJ acceptance before purchasing

Compatibility warning: This table groups products by panel family only. It is NOT a cross-reference proving any individual panel and kit are compatible. Verify catalog number, series, main breaker type/location, generator breaker type, mounting arrangement and manufacturer instructions.

Individual Kit and Manufacturer Options

For supported Square D QO panels

Schneider Electric QO OEM interlock

QO family only

Verify fit

Panel familyQO family only

Selection ruleExact catalog and series

InstallationQualified electrician

Manufacturer accessory; confirm exact QO load-center catalog number, series, breaker arrangement and approved kit code. A matching brand name, main breaker amperage or similar-looking panel cover does not establish an approved fit.

Why consider it

Manufacturer documentation identifies a relevant interlock product family for a compatible installation.

Before purchase

Obtain the exact kit instructions, labeling requirements and acceptance from your installer and AHJ. Confirm compatible breaker and inlet equipment separately.

Manufacturer reference: Official documentation.

Check Price

For supported Square D Homeline panels

Schneider Electric Homeline OEM interlock

Homeline family only

Verify fit

Panel familyHomeline family only

Selection ruleExact catalog and series

InstallationQualified electrician

Not interchangeable with QO. Confirm panel series, main breaker location and manufacturer installation sheet. A matching brand name, main breaker amperage or similar-looking panel cover does not establish an approved fit.

Why consider it

Manufacturer documentation identifies a relevant interlock product family for a compatible installation.

Before purchase

Obtain the exact kit instructions, labeling requirements and acceptance from your installer and AHJ. Confirm compatible breaker and inlet equipment separately.

Manufacturer reference: Official documentation.

Check Price

For compatible Eaton BR load centers

Eaton BR mechanical interlock

Eaton BR family only

Verify fit

Panel familyEaton BR family only

Selection ruleExact catalog and series

InstallationQualified electrician

Eaton lists multiple BR mechanical interlock kits. Match exact panel catalog and main breaker family; BRMIKBR is not universal. A matching brand name, main breaker amperage or similar-looking panel cover does not establish an approved fit.

Why consider it

Manufacturer documentation identifies a relevant interlock product family for a compatible installation.

Before purchase

Obtain the exact kit instructions, labeling requirements and acceptance from your installer and AHJ. Confirm compatible breaker and inlet equipment separately.

Manufacturer reference: Official documentation.

Check Price

Documented third-party QO option

Westinghouse WLock QO

Specified QO G/S series only

Verify fit

Panel familySpecified QO G/S series only

Selection ruleExact catalog and series

InstallationQualified electrician

Westinghouse limits this kit to certain Square D QO indoor and outdoor series and breaker arrangements. Local approval still required. A matching brand name, main breaker amperage or similar-looking panel cover does not establish an approved fit.

Why consider it

Manufacturer documentation identifies a relevant interlock product family for a compatible installation.

Before purchase

Obtain the exact kit instructions, labeling requirements and acceptance from your installer and AHJ. Confirm compatible breaker and inlet equipment separately.

Manufacturer reference: Official documentation.

Check Price

Aftermarket alternative where accepted

GenInterlock panel-specific kits

Exact supported panel only

Verify fit

Panel familyExact supported panel only

Selection ruleExact catalog and series

InstallationQualified electrician

Manufacturer offers panel-specific MET-listed products. Verify the exact SKU, independent listing documentation, and AHJ acceptance before purchasing. A matching brand name, main breaker amperage or similar-looking panel cover does not establish an approved fit.

Why consider it

Manufacturer documentation identifies a relevant interlock product family for a compatible installation.

Before purchase

Obtain the exact kit instructions, labeling requirements and acceptance from your installer and AHJ. Confirm compatible breaker and inlet equipment separately.

Manufacturer reference: Official documentation.

Check Price

How to Find a Kit That Actually Fits Your Panel

Ask your electrician to identify the exact load-center manufacturer, catalog number, series, main breaker configuration and required generator breaker type from the factory labeling and approved documentation. The outer panel door may expose identifying labels; do not remove the dead-front cover or contact internal electrical components.

01 - IdentifyManufacturer + catalog number

QO and Homeline are different panel families; Eaton BR has multiple configurations.

02 - MatchSeries + breaker layout

Compare the exact model against the official compatibility chart and instructions.

03 - ApproveListing + local inspector

Have your electrician confirm the listing, permitted configuration and AHJ requirements.

OEM vs Aftermarket: What Listing Actually Means

Schneider Electric explains that its QO and Homeline generator interlock accessories are evaluated under the load center's UL 67 listing, rather than necessarily having separate standalone UL listings. Eaton also documents UL-listed mechanical interlock solutions. Aftermarket manufacturers may provide independent MET listing documentation; that does not automatically make every kit approved for every panel. Confirm the exact product, installation configuration and local acceptance.

Do not mix panel brands. Schneider specifically warns against using a Square D interlock on another manufacturer's load center because that combination is not tested or listed by Schneider.

Generator Backfeed, Transfer Equipment and Safety

A properly designed mechanical interlock prevents the main utility breaker and the generator supply breaker from being ON simultaneously. The device is only one component of a compliant generator connection: the installer must also address an approved power inlet, compatible breakers and retainers, wiring, overcurrent protection, labeling, grounding/bonding, generator neutral configuration, permits and inspections as applicable.

What an interlock can do

Mechanically prevent simultaneous operation of the intended main and generator breakers.
Allow a qualified electrician to design selected circuit backup using an approved panel configuration.
Keep existing branch circuits in the panel available for managed generator use.

What it cannot do

Make an incompatible panel or breaker arrangement safe.
Increase the generator's wattage or eliminate the need for load management.
Replace required grounding, neutral, inlet, permitting or inspection work.
Authorize connecting a generator with a double-male cord or household receptacle backfeed.

Professional installation only: Do not install, modify or operate panel interlock hardware based solely on an online article. An incorrect interlock can expose people to energized conductors and dangerous utility backfeed. Hire a qualified licensed electrician, follow the panel and generator manufacturers' instructions, and obtain AHJ approval.

Interlock Kit vs Manual Transfer Switch

An interlock uses the existing compatible service panel and typically requires manual load management. A manual transfer switch can offer a dedicated, clearly labeled circuit-selection interface. Generac notes that interlocks are not universally accepted in every jurisdiction and recommends a manual transfer switch for its own backup-system guidance. A transfer switch may be the better route if no approved interlock exists for your exact panel.

What to Check Before Ordering

Exact panel: Manufacturer, model, series, main breaker style and position.
Official fit: Matching kit part number and approved breaker arrangement.
Certification: Applicable load-center listing or independent kit documentation.
AHJ: Local permit, inspection and acceptance requirements.
Generator system: Inlet, cord, breaker, neutral configuration and load plan designed by the electrician.
Product: Installation instructions, included hardware and required labels.

Final Verdict: Fit and Approval Matter More Than Price

Start with the panel manufacturer's approved interlock for your exact load center. If no OEM option exists, a documented aftermarket kit may be considered only after a qualified electrician and local AHJ verify the installation. If neither option is approved, use properly designed transfer equipment rather than forcing a near match.

Frequently Asked Questions

Are generator interlock kits universal?

No. Fit depends on the exact panel model, series, main breaker location and compatible generator breaker. A similar-looking plate is not proof of compatibility.

Is a Square D QO kit compatible with Homeline?

Not by default. QO and Homeline are distinct load-center families with different manufacturer-documented interlock accessories.

Does a generator interlock prevent backfeeding?

A correctly installed, approved interlock is designed to block simultaneous ON positions of the main utility breaker and generator breaker. The rest of the electrical system must also be installed correctly.

Are aftermarket interlock kits code compliant?

Some have independent listing documentation, but local acceptance and exact panel compatibility must be confirmed. A blanket claim for all aftermarket kits would be inaccurate.

Can I install a generator interlock myself?

Panel modifications involve potentially lethal electrical hazards. Use a qualified licensed electrician and comply with local permitting and inspection requirements.

What if my panel has no compatible kit?

Ask an electrician about a properly rated manual transfer switch, approved transfer equipment or a panel upgrade instead of adapting an incompatible kit.

Can an interlock power the entire house?

It does not increase generator capacity. Connected circuits still need load management and may exceed the generator's output if operated together.

Do I need a generator inlet and a special cord?

A compliant installation typically uses appropriate listed connection equipment. The exact inlet, cord, breaker, neutral and protection arrangement must be designed for the generator and panel.

Sources and Editorial Methodology

We compared documented panel-specific accessory families and manufacturer safety guidance. This is not a field test or an electrical installation tutorial. No product is presented as compatible without a panel-specific verification.