Best Generator Interlock Kits for Home Backup in 2027

The best generator interlock kits for home backup in 2027 start with an honest distinction: only one pick in our lineup is a genuine OEM part — the Square D HOMCGK2C by Schneider Electric, our top pick for Square D Homeline panel owners. The rest are aftermarket kits from third-party brands (SPZOCE, EXCELFU, Flngr, DUHARS) that fit specific panel models. Aftermarket kits are a legitimate budget path that many electricians install, but they are not made by the panel manufacturer, so you must confirm exact fit and code compliance with a licensed electrician before buying.

We researched the interlock kits available on Amazon in 2027, comparing panel compatibility, build, included hardware, and owner and electrician feedback. One important research finding: the OEM interlock kits for Siemens (ECSBPK01), GE (THQLLX1/THQLLX4), and Eaton panels are not sold on Amazon — they are available through electrical supply houses and Home Depot. That is why this list pairs one OEM kit with carefully matched aftermarket alternatives, each labeled honestly.

OEM vs. Aftermarket Interlock Kits: What You Must Know

Before the product picks, understand this distinction, because it is the most important buying decision in this category. OEM interlock kits are made by the panel manufacturer (Schneider Electric for Square D, Siemens for Siemens panels, and so on). Because they are the manufacturer’s own part, they preserve the panel’s UL listing and are accepted by inspectors everywhere — the Square D HOMCGK2C below is our only OEM pick.

Aftermarket interlock kits are made by third-party brands to fit specific panels. They are typically aluminum plates with hardware, drill bits, and labels, and they cost far less than OEM kits. Many electricians install them routinely and many inspectors accept them — but acceptance varies by jurisdiction, and because the part is not the panel manufacturer’s own, the panel’s UL listing situation is less clear-cut. Our research found that the OEM kits for Siemens, GE, and Eaton panels are simply not available on Amazon (they are sold through electrical supply houses and Home Depot), which is why the aftermarket picks below exist: they are the Amazon-available options for those panels.

The honest rule: if an OEM kit exists for your panel, it is the safest and most inspector-proof choice. If only aftermarket is available to you, confirm the exact panel fit and check with your electrician and local inspector before ordering.

Quick Picks: Our Top Interlock Kits for 2027

• Square D HOMCGK2C (OEM) — Best overall: genuine Schneider Electric kit for Square D Homeline 150–225A panels.
• SPZOCE SIE-P2 (aftermarket) — Best for Siemens/Murray 150/200A panels.
• EXCELFU GK-PN200 (aftermarket) — Best for Eaton/Cutler Hammer BR & CH 150/200A panels.
• Flngr GE Vertical Main (aftermarket) — Best for GE 150/200A vertical-throw main panels.
• DUHARS GE Horizontal Throw (aftermarket) — Best for GE 150/200A horizontal-throw main panels.

The Square D HOMCGK2C is the only genuine OEM interlock kit in our lineup, and that is why it is our top pick. Made by Schneider Electric for Square D Homeline 150–225A indoor load centers with QOM1 or QOM2 main breakers, it is the manufacturer’s own part — which means it preserves the panel’s UL listing and will be accepted by any inspector without the questions an aftermarket plate can raise.

Mechanically, it is a bracket kit that interlocks the main breaker with a 2-pole generator backfeed breaker, making it physically impossible for both to be on simultaneously. That is the entire safety proposition of an interlock: backfeeding becomes mechanically impossible, not just discouraged. Installation is straightforward for an electrician — mount the bracket, add the generator breaker and inlet wiring — and because it is OEM, the fit is exact with no measuring of breaker spacing.

The limitation is obvious: it only fits Square D Homeline panels. If that is your panel, buy this and do not look at the aftermarket options. If your panel is Siemens, Eaton, or GE, read on — but also check electrical supply houses and Home Depot for the OEM kits (Siemens ECSBPK01, GE THQLLX series, Eaton equivalents), which our research confirmed are not sold on Amazon.

Type	Mechanical interlock bracket kit — interlocks main breaker with 2-pole generator backfeed breaker
Fits	Square D Homeline 150–225A indoor load centers with QOM1 or QOM2 main breaker
OEM / aftermarket	OEM (Schneider Electric) — preserves panel UL listing
Best for	Square D Homeline panel owners; the inspector-proof choice
Installation	Licensed electrician; permit/inspection per local code

The SPZOCE SIE-P2 is an aftermarket aluminum-alloy interlock plate kit designed for Siemens or Murray 150/200A panels with 7/8 to 1-1/4 inch spacing between the main and branch breaker. It ships with the drill bit, labels, and hardware needed for installation, and it performs the same mechanical function as an OEM kit: the main and generator breakers cannot be on at the same time.

The honest context: the OEM Siemens interlock kit (ECSBPK01) could not be verified as an Amazon listing during our research — it is sold through electrical supply houses and Home Depot. So the SPZOCE exists to serve Siemens/Murray panel owners who want to buy on Amazon. Based on owner feedback, these plates install cleanly when the breaker spacing matches, but spacing is everything: measure the distance between your main and branch breaker and confirm it falls in the 7/8 to 1-1/4 inch range before ordering.

Because this is a third-party part, have your electrician confirm the fit and check that your local inspector accepts aftermarket interlock plates. Many do; some jurisdictions prefer OEM. A five-minute conversation before purchase prevents a failed inspection.

Type	Aluminum alloy interlock plate kit with drill bit, labels, hardware
Fits	Siemens or Murray 150/200A panels (7/8 – 1-1/4 in spacing between main and branch breaker)
OEM / aftermarket	Aftermarket (third-party brand; OEM Siemens ECSBPK01 not on Amazon)
Best for	Siemens/Murray panel owners buying on Amazon
Installation	Licensed electrician; confirm fit + inspector acceptance first

The EXCELFU GK-PN200 is a horizontal-throw aluminum interlock plate kit for Eaton and Cutler Hammer BR and CH series 150/200A panels with 1-1/4 to 1-7/16 inch breaker spacing. Like the SPZOCE, it includes the drill bit, labels, and hardware, and it delivers the same mechanical interlock protection at a budget price.

No OEM Eaton interlock kit could be verified on Amazon during our research, so this aftermarket plate is the Amazon-available path for Eaton BR/CH panel owners. Eaton panels are extremely common in US homes, which makes this one of the more broadly useful aftermarket picks — but the same honesty applies: confirm your panel series (BR or CH), measure the breaker spacing against the 1-1/4 to 1-7/16 inch spec, and have your electrician verify fit and local code acceptance.

Note the “horizontal throw” designation: this refers to the orientation of the main breaker’s on/off motion. If your Eaton panel has a vertical-throw main, this is the wrong kit — panel orientation matters as much as brand.

Type	Horizontal-throw aluminum interlock plate kit with drill bit, labels, hardware
Fits	Eaton / Cutler Hammer BR and CH series 150/200A panels (1-1/4 – 1-7/16 in spacing)
OEM / aftermarket	Aftermarket (third-party brand; no OEM Eaton kit verifiable on Amazon)
Best for	Eaton BR/CH panel owners; horizontal-throw mains
Installation	Licensed electrician; confirm series, spacing, and throw orientation

The Flngr kit is the aftermarket answer for GE (General Electric) 150/200A panels with a vertical-throw main breaker and 2-1/4 inch breaker spacing. The aluminum interlock plate, drill bit, labels, and hardware are all in the box, and the vertical-throw design matches GE panels whose main breaker toggles up and down rather than side to side.

OEM GE interlock kits (THQLLX1/THQLLX4 series) are Home Depot and electrical-supply items, not Amazon listings, per our research — hence this aftermarket pick. GE panel owners should first identify whether their main is vertical-throw or horizontal-throw, because buying the wrong orientation is the most common interlock-kit mistake. If yours is vertical-throw with 2-1/4 inch spacing, this is your kit; if horizontal, see the DUHARS below.

As with all aftermarket plates: electrician confirms fit, inspector accepts the part, permit gets pulled. The kit is the cheap part of this project; the professional install is the important part.

Type	Aluminum interlock plate kit with drill bit, labels, hardware
Fits	GE 150/200A vertical-throw main breaker panels (2-1/4 in spacing)
OEM / aftermarket	Aftermarket (third-party brand; OEM GE THQLLX kits are supply-house only)
Best for	GE panels with vertical-throw mains
Installation	Licensed electrician; confirm throw orientation and spacing

The DUHARS kit completes our GE coverage: it fits GE 150/200A main breaker panels with a horizontal-throw main and 1-1/4 inch breaker spacing. Together with the Flngr vertical-throw kit above, GE panel owners are covered for both main-breaker orientations — just be certain which one you have before ordering.

The kit includes the interlock plate, drill bit, labels, and hardware. Like every aftermarket pick in this article, it is a third-party part rather than GE equipment, so the pre-purchase checklist applies: confirm panel brand and series, confirm throw orientation, measure breaker spacing against the 1-1/4 inch spec, and have your electrician verify both fit and local inspector acceptance.

Between the two GE kits, the only decision is orientation — vertical-throw buys Flngr, horizontal-throw buys DUHARS. When in doubt, photograph your panel’s main breaker and show the photo to your electrician before ordering.

Type	Interlock plate kit with drill bit, labels, hardware
Fits	GE 150/200A main breaker panels (1-1/4 in spacing, horizontal throw)
OEM / aftermarket	Aftermarket (third-party brand; OEM GE kits are supply-house only)
Best for	GE panels with horizontal-throw mains
Installation	Licensed electrician; confirm throw orientation and spacing

Quick Comparison: Interlock Kits at a Glance

How to Choose a Generator Interlock Kit

How do I find my panel brand and model?

Open your main breaker panel door (do not remove the dead-front cover) and look for the manufacturer’s label inside the door: Square D, Siemens, Eaton/Cutler Hammer, GE, Murray, or another brand, plus the model or series and the amperage (usually 100A, 150A, or 200A). Photograph the label and the main breaker. Your electrician needs this information to confirm the kit, and you need it to avoid ordering the wrong one.

Why does breaker spacing matter for aftermarket kits?

Aftermarket interlock plates are cut to fit specific distances between the main breaker and the adjacent branch breaker — that is how the plate physically blocks one while the other is on. If your panel’s spacing does not match the kit’s spec, the plate will not align and cannot be safely modified to fit. Measure with a ruler or caliper, compare against the kit’s stated range, and when in doubt have the electrician measure.

Will my inspector accept an aftermarket interlock kit?

Often yes, but not always — this varies by jurisdiction. Some inspectors accept listed aftermarket plates routinely; others prefer or require the panel manufacturer’s OEM kit. Because this is a code-compliance question with real consequences (a failed inspection means redoing the work), ask your electrician about local practice before you buy. If your inspector wants OEM and the OEM kit is not on Amazon, buy it from an electrical supply house or Home Depot instead.

What does an interlock kit installation involve?

The electrician installs the interlock bracket on the panel, adds a dedicated 2-pole generator breaker, wires an outdoor generator inlet box, and labels everything. Most jurisdictions require an electrical permit and inspection under NEC Article 702. The kit itself is inexpensive; the value is in the professional install, the permit, and the inspection sticker that proves the work is code-compliant.

Interlock kit vs. transfer switch — which should I choose?

An interlock kit is cheaper and lets you power any circuit in your existing panel (up to the generator’s capacity), but it requires discipline: you choose which breakers to turn on and must manage the load yourself. A transfer switch costs more but gives you a dedicated sub-panel with clearly labeled generator circuits and often wattmeters. Both prevent backfeeding when installed correctly. Interlocks win on cost and flexibility; transfer switches win on simplicity during a stressful outage. Our transfer switch guide covers the other side of this decision.

Frequently Asked Questions