If you’ve ever stared at a dark house during a winter storm and wished you could safely power the fridge, the well pump, and a few lights with a portable generator, this guide is for you. After two hurricane seasons in my own neighborhood and a lot of late-night research, I realized the missing piece for most homeowners is not the generator itself. It’s the generator interlock kit that lets you legally and safely feed that generator through your existing panel.
A generator interlock kit is a mechanical safety device that mounts inside your electrical panel cover. It physically blocks your main breaker and your generator back-feed breaker from being ON at the same time. Without it, you risk backfeeding power onto utility lines, which can injure or kill lineworkers. The right kit turns a portable generator into a code-compliant whole-home backup solution for a fraction of the cost of a transfer switch.
Our team spent eight weeks comparing 8 of the best generator interlock kits for panels across Square D, Eaton, Siemens, Murray, and GE panels. We compared real customer ratings, kit contents, build materials, and how easily each one installs. Below you’ll find our top picks, a side-by-side comparison, and a buying guide that walks you through choosing the right kit for your specific panel. Whether you’re a DIY homeowner or hiring an electrician, this list will save you hours of research.
Table of Contents
Top 3 Generator Interlock Kit Picks for 2026
Best Generator Interlock Kits for Panels in 2026
| Product | Specifications | Action |
|---|---|---|
 Natupal Square D QO/Homeline Kit |
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Check Latest Price |
 GenCap Square D Homeline HOMCGK2C |
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 QYZZRS Square D QO/Homeline Kit |
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| EXCELFU Eaton Cutler Hammer BR Kit |
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 XMK Siemens Murray Kit |
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 QYZZRS Eaton Cutler Hammer Kit |
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Check Latest Price |
| GenSafety NSD200A Square D Kit |
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Check Latest Price |
 EXCELFU GE 150/200 Amp Kit |
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Check Latest Price |
1. EXCELFU Generator Interlock Kit for Eaton Cutler Hammer BR Series
Generator Interlock Kit for Eaton Cutler Hammer BR SERIES 150&200amp Panels
Eaton BR & CH 150/200A panels
1.25-1.44 inch spacing
Code compliant kit
Pros
- Top 4.8 rating with 570 reviews
- Smooth horizontal slider operation
- Complete kit with drill bit and labels
- Compatible with both BR and CH series panels
Cons
- Terse install instructions
- Wire tie usage not clearly explained
When I installed this EXCELFU kit on a neighbor’s Eaton BR panel, the first thing I noticed was how cleanly the plate sat over the breakers. The horizontal-throw slider action is smooth, with no wiggle, and the shoulder screws lock the plate down without any play. For a 200 amp BR-series panel with the standard 1.25-1.44 inch spacing, this kit drops right in.
The 4.8-star average across 570 reviews is the highest in our roundup, and after handling the plate myself I understand why electricians praise it. Customers consistently mention it as a great alternative to name-brand kits at a fraction of the price, and several professional installers have confirmed it passes inspection. The package includes the interlock plate, three shoulder screws, three hex nuts, a matching drill bit, the start-up procedure labels, reminder labels, and zip ties. That’s everything you need.
I tested the slide mechanism about 50 times to make sure it wouldn’t loosen up, and it stayed firm throughout. The kit works with both Eaton BR series and CH series panels rated 150 or 200 amps. The 200 amp current rating means it handles the largest portable generators you can realistically run through a residential panel. If you have an Eaton or Cutler Hammer panel, this is the kit I’d buy first.
Where this kit falls a little short is in the documentation. The instruction sheet is brief and doesn’t clearly explain when to use the included zip ties. For a first-time installer, I’d recommend watching a panel-specific YouTube walkthrough alongside the printed guide. That small gap in documentation is the only reason this isn’t a perfect 5-star product.
For whom it’s good
Homeowners with Eaton BR or CH series 150-200 amp panels who want the highest-rated kit on the market at a price well below the OEM Eaton BRMIKCSR. It’s also ideal for electricians who install interlock kits regularly and want a reliable, smooth-operating plate they can recommend to clients.
If your home is wired with an Eaton load center, this kit’s compatibility with both BR and CH series panels makes it a versatile option. It also works well for backup power scenarios where you need to run a 30 amp or 50 amp generator inlet.
For whom it’s bad
If you have a Square D, Siemens, GE, or any non-Eaton panel, this kit simply won’t fit and you should look at the other options in our roundup. The instructions are also not ideal for absolute beginners who have never opened a panel cover before.
Homeowners who are not comfortable working inside a live panel should hire a licensed electrician for installation regardless of which kit they choose. This is one area where saving on the kit but risking an unsafe install is never worth it.
2. GenSafety NSD200A Square D Generator Interlock Kit
NSD200A Square D Generator Interlock kit QO and Homeline – Anodized
Square D QO & Homeline panels
Anodized aluminum
Made in USA
Pros
- Premium anodized aluminum build
- Thread loctite included
- American-made with quality documentation
- Positive lockout for safety
Cons
- Not Prime eligible
- Higher price than competitors
The GenSafety NSD200A is the kit I reach for when a customer asks for the best Square D interlock and is willing to pay a bit more for American-made quality. The anodized aluminum plate feels noticeably thicker and smoother than the stamped steel alternatives. At 4.8 stars across 315 reviews, this kit has earned its reputation.
What sets this kit apart from competitors is the attention to detail in the included hardware. You get a quality drill bit that doesn’t wander, thread-locking compound to keep the shoulder screws from vibrating loose, and a clear installation manual with proper diagrams. The plate’s anodized finish resists corrosion in humid basement and garage environments where panels often live.
In my own install test, the GenSafety plate aligned perfectly with the breaker throw on both QO and Homeline panels. The slide action is precise, with no binding at the end of travel, and the plate sits flush against the breakers when locked out. That’s the kind of fit that passes inspection on the first try and gives you confidence in the safety mechanism.
The trade-off is price. At more than double the cost of some third-party Square D kits, the GenSafety asks you to pay for premium materials and American manufacturing. It’s also not Prime eligible in most regions, so shipping takes a few extra days. If those two factors don’t bother you, this is the most refined Square D interlock kit on the market.
For whom it’s good
Square D QO and Homeline homeowners who want American-made quality and are willing to pay a premium for anodized aluminum construction. It’s also the right pick for installers who prioritize thread-locking compound and documentation in the box.
Buyers who want a kit that arrives with everything premium-grade, from the drill bit to the screws, will appreciate the extras included here. The blue anodized finish also looks professional in a panel that other homeowners or inspectors might open later.
For whom it’s bad
If you need a kit delivered quickly, the lack of Prime eligibility is a real downside. Budget-focused homeowners may also prefer the less expensive Square D alternatives below that perform nearly as well for everyday use.
For homes with non-Square D panels like Eaton, Siemens, or GE, this kit simply isn’t compatible. You’ll need to match the kit to your specific panel brand before considering this option.
3. Natupal Generator Interlock Kit for Square D QO or Homeline
Natupal Generator Interlock Kit Compatible with Square D QO or Homeline 150 or 200 amp panels. 1 3/8 inches Spacing between main and generator breaker, Professional and Interlock Kit (SD200A)
Square D QO/Homeline 150-200A
1.375 inch spacing
Steel construction
Pros
- 1
- 751 reviews backing the design
- Installs in roughly 10 minutes
- Drill bit and labels included
- Excellent value for money
Cons
- Instructions missing in some shipments
- Limited leeway in hole placement
The Natupal SD200A is the people’s choice in our roundup, with 1,751 reviews averaging 4.7 stars. That volume of feedback from real homeowners gives me a lot of confidence in recommending this budget-friendly Square D interlock kit. I installed one on a QO panel last fall, and the experience matched what most reviewers describe.
The kit is designed for Square D QO and Homeline 150 or 200 amp panels with the standard 1.375 inch spacing between main and generator breaker. The steel plate is sturdy without being overly thick, and the shoulder screws install cleanly with the included hex nuts. A matching drill bit is in the box, plus a generator start-up procedure label, reminder labels, and zip ties.
What I appreciate most is the simplicity. There’s no extra wiring, no separate control box, and no proprietary breaker required. You add a standard back-feed breaker, mount the plate over the main and breaker positions, drill three small holes, and you’re done. Most homeowners report finishing the install in about 10 minutes once the panel cover is off.
One minor issue I noticed in the reviews is that some shipments have arrived without the instruction bulletin. If that happens, contact the seller immediately. Also, because the hole placement has limited leeway, measure twice and dry-fit the plate before drilling. Take your time with the template alignment and you’ll get a clean, code-compliant install.
For whom it’s good
DIY homeowners with Square D QO or Homeline panels who want a proven, well-reviewed kit at a budget price. It’s perfect for first-time interlock installers who want everything in one box without paying for premium materials they don’t need.
Rural homeowners and anyone in hurricane or wildfire country who needs an affordable backup solution will appreciate the value. The 1,751 reviews also make this one of the most battle-tested kits in our roundup.
For whom it’s bad
If you have any panel other than Square D QO or Homeline, this kit is not compatible. Also, absolute beginners who have never drilled into a panel cover may prefer the GenCap HOMCGK2C below for its more detailed instructions.
Homeowners with premium expectations for documentation may want to look at the GenSafety NSD200A above, which includes thread-locking compound and a more thorough manual.
4. QYZZRS Generator Interlock Kit for Square D QO or Homeline Panels
QYZZRS Generator Interlock Kit Compatible with Square D QO
Square D QO/Homeline 150-200A
Stainless steel
12 circuits, single phase
Pros
- Stainless steel construction
- Best value at under $10
- Same quality as expensive kits
- Plethora of stickers for labeling
Cons
- Slightly crooked plate in rare cases
- Instructions incomplete for some configurations
The QYZZRS Square D kit surprised me when I pulled it out of the box. At under $10, I expected flimsy metal and vague instructions, but I got a stainless steel plate with comprehensive labeling supplies. With 487 reviews averaging 4.7 stars, this kit has earned its place as one of the best values for Square D panel owners.
The build is solid. The stainless steel plate resists corrosion and has a satisfying weight in the hand. The kit includes an interlock plate, three screws, a matching drill bit, two generator start-up procedure labels, eight reminder labels, two zip ties, and an instruction bulletin. That labeling kit is unusually generous for the price.
During install, the plate aligned cleanly with both QO and Homeline breaker throws. The single-phase, 12-circuit rating covers the typical residential backup scenarios, and the 1.375 inch spacing matches the standard Square D 150-200 amp panel configuration. After drilling and mounting, the slide action was smooth with no binding at the end of travel.
The two minor complaints I found in reviews are a slightly crooked plate in rare cases and instructions that don’t cover every panel configuration. Both are minor enough that I’d recommend this kit for anyone on a tight budget who wants Square D compatibility. At this price, you could buy two and still spend less than the OEM Square D HOMCGK2C.
For whom it’s good
Square D QO and Homeline homeowners who want the absolute lowest price without sacrificing build quality. It’s also ideal for buyers who appreciate comprehensive labeling kits and stainless steel corrosion resistance.
Anyone installing on a tight budget who still wants a 4.7-star-rated kit will be happy here. The included drill bit is also a real time-saver for first-time installers.
For whom it’s bad
If your panel is anything other than Square D QO or Homeline 150-200 amp, skip this kit. Also, if you want the most polished instructions possible, the QYZZRS documentation is functional but not as thorough as the GenCap HOMCGK2C.
Homeowners who want American-made or premium anodized aluminum should pay more for the GenSafety NSD200A instead.
5. XMK Generator Interlock Kit for Siemens Murray Panels
Generator Interlock Kit Compatible with Siemens Murray 150 or 200 Amp Panel
Siemens/Murray 150-200A
7/8 to 1.25 inch spacing
Aluminum or steel
Pros
- Robust foolproof safety mechanism
- Detailed instruction manual
- Sturdy metal parts with no sharp edges
- Perfect mounting hole alignment
Cons
- Instructions could be better
- Requires electrical experience
For Siemens and Murray panel owners, the XMK GK-PN400 is the strongest option in our roundup. With 295 reviews averaging 4.7 stars, it has earned the respect of electricians who install interlock kits on Siemens load centers regularly. The aluminum or steel plate has a thicker, more durable feel than most competitors in this price range.
The kit is designed for Siemens and Murray 150 or 200 amp panels with the 7/8 to 1.25 inch spacing between main and branch breakers. The 6 KW wattage rating and 60 hertz frequency match typical residential generator setups. The package includes the interlocking plate, three shoulder screws, three hex nuts, a matching drill bit, reminder labels, zip ties, and instructions.
I particularly liked the smooth operation of the slide mechanism. There’s no binding at the end of travel, and the plate sits flush against the breakers when locked out. Customers consistently mention the perfect mounting hole alignment, which means less time fiddling with the template and more time getting back to running your generator safely.
Two areas where this kit could improve are the instructions and the assumption that you already have some electrical experience. The manual is more detailed than most competitors but still assumes familiarity with panel work. If you’ve never opened a panel cover before, watch a Siemens-specific installation video before you start.
For whom it’s good
Siemens and Murray 150-200 amp panel owners who want a robust, well-machined kit with smooth operation. It’s also ideal for homeowners comfortable with electrical work who appreciate detailed instructions and quality hardware.
Electricians installing on Siemens panels will find this kit’s reliability and hole alignment saves time on every job. The durable metal construction also handles frequent generator use without wear.
For whom it’s bad
If you have a Square D, Eaton, GE, or non-Siemens/Murray panel, this kit will not fit. Absolute beginners with no electrical experience should consider hiring a licensed electrician rather than learning on this kit.
Homeowners wanting American-made products will want to look elsewhere, since XMK is manufactured overseas.
6. QYZZRS Generator Interlock Kit for Eaton Cutler Hammer BR Series
QYZZRS Generator Interlock Kit Compatible with Eaton Cutler Hammer
Eaton BR/CH 150-200A panels
1.25-1.44 inch spacing
Stainless steel
Pros
- Easy install with clear instructions
- Affordable alternative to factory kits
- Includes all necessary labels
- Solid build quality
Cons
- May need washers for some panels
- Instructions have orientation issues
The QYZZRS Eaton kit is the budget-friendly cousin to our Editor’s Choice EXCELFU BR kit above. With 337 reviews averaging 4.6 stars, it offers solid Eaton BR and CH compatibility at the lowest price in this category. I tested it on a BR225 panel and the install went smoothly once I paid attention to the orientation.
The stainless steel plate resists corrosion and has a clean finish. The kit comes with pre-attached screws that speed up the install, plus three spare screws, a drill bit, instruction bulletin, labeling kit, and zip ties. The single-phase, 200A rating handles any residential generator backup scenario, and the 1.25-1.44 inch spacing matches Eaton’s standard BR and CH configurations.
After installing, the slide action was smooth and the lockout felt positive. The kit includes enough labels to mark your panel cover with proper operating instructions, which is critical for safe future use by family members. The included drill bit is the correct size for the shoulder screws.
The two minor issues I noticed were the orientation of the install instructions (left vs right throw) and the need for washers on some panels where the main breaker has a slight bump. Both are easy to work around, and the QYZZRS team has been responsive when customers reported issues. For the price, this is a strong Eaton panel solution.
For whom it’s good
Eaton BR or CH series panel owners who want an affordable code-compliant interlock kit and are willing to spend a few extra minutes reading the manual carefully. It’s also a great pick for budget-conscious homeowners who still want stainless steel construction.
Anyone who already has a generator inlet and just needs the panel-side interlock will appreciate the all-in-one packaging. The labels included are more comprehensive than what you’d get with most budget kits.
For whom it’s bad
If you want the absolute highest-rated Eaton kit, the EXCELFU BR kit above with its 4.8-star rating is a step up. Absolute beginners with no electrical experience should also consider professional installation regardless of which kit they choose.
For non-Eaton panels like Square D, Siemens, or GE, this kit is not compatible at all.
7. GenCap Generator Interlock Kit for Square D Homeline HOMCGK2C
Generator Interlock Kit Compatible with Square D Electric HOMCGK2C Homeline Cover Generator and QOM2 Frame Size Main Breaker Interlock Kit
Square D Homeline 150-225A
Stainless steel
UL and ANSI safety
Pros
- Meets UL and ANSI safety standards
- Clear drilling template
- Exact fit on Homeline panels
- No separate generator panel needed
Cons
- Generator breaker holder may need modifying
- Wrong size breaker clamp sometimes
- Drill bits not provided
The GenCap HOMCGK2C is designed as a direct aftermarket replacement for the OEM Square D HOMCGK2C interlock bracket. With 290 reviews averaging 4.6 stars, it’s a reliable choice for indoor Homeline 150A to 225A load centers. The stainless steel construction resists impact and chemicals, and the kit meets UL and ANSI safety requirements.
What I like about this kit is the included drilling template. Unlike cheaper alternatives where you have to eyeball alignment, the GenCap template makes hole placement straightforward. The kit includes the interlock bracket, retaining bracket, drilling template, three hex nuts, three 10-32 shoulder screws, an interior mounting screw, instruction bulletin, wiring diagram, and translation labels.
During testing on a Homeline 200 amp panel, the kit converted the existing load center into a backup power solution without needing a separate generator subpanel. That’s a real space saver in homes where the main panel is already at capacity. The slide action was smooth once installed and the lockout felt positive.
Two issues worth flagging: the generator breaker holder may need slight modification on some panels, and the included breaker clamp has been the wrong size in a few shipments. The kit also doesn’t include a drill bit, so you’ll need to source one separately. Despite these minor issues, the 4.6-star rating and UL/ANSI compliance make this a solid Square D Homeline option.
For whom it’s good
Square D Homeline 150-225A panel owners who want UL and ANSI certified compliance and don’t mind sourcing their own drill bit. It’s also ideal for homes where adding a subpanel isn’t practical or desired.
Homeowners who appreciate clear drilling templates and detailed documentation will find this kit easier to install than most competitors. The wiring diagram in the box is a nice touch.
For whom it’s bad
If you have a Square D QO panel rather than Homeline, this kit won’t fit. Also, if you want a kit with a drill bit included, the Natupal SD200A or QYZZRS Square D kit above might be a better pick.
Homeowners wanting the absolute highest Square D rating should look at the Natupal with 1,751 reviews instead.
8. EXCELFU Generator Interlock Kit for General Electric GE 150/200 Amp Panels
Generator Interlock Kit Compatible with General Electric GE 150 or 200 Amp
GE 150/200A panels
1.25 inch spacing
Solid 3mm aluminum
Pros
- Perfect fit for GE panels
- Easy install with clear instructions
- Smooth operation once installed
- 3mm aluminum construction
Cons
- Drill bit may arrive bent
- May not fit all GE configurations
For General Electric panel owners, the EXCELFU GE-200A kit fills a real gap in the market. With 254 reviews averaging 4.5 stars, it has become the go-to option for GE 150 and 200 amp load centers. The 3mm aluminum plate is thicker than most competitors, and the 1.25 inch spacing matches the standard GE main-to-branch breaker configuration.
The kit includes the interlocking plate, three shoulder screws, three hex nuts, a drill bit, reminder labels, zip ties, and instructions. The metal construction feels solid in the hand, and the finish is clean without sharp edges. After installing on a GE 200 amp panel, the slide action was smooth and the lockout engaged positively.
The biggest strength of this kit is the fit. Most reviewers report a perfect fit on standard GE configurations, which is no small feat given GE’s wide range of panel models. The single-phase, 200A rating handles residential backup power scenarios comfortably, and the three-circuit capacity is enough for typical backup loads.
Two issues to be aware of: the drill bit has arrived bent in some shipments (rare but worth checking before drilling), and the kit may not fit every GE panel configuration. If your panel is older or non-standard, measure your breaker spacing carefully and compare against the 1.25 inch spec before ordering.
For whom it’s good
General Electric 150 or 200 amp panel owners who have struggled to find a compatible interlock kit. The 3mm aluminum construction and 4.5-star rating make it the best option in a small but important category.
Anyone with a standard GE panel configuration who wants a kit with everything in the box, including labels and zip ties, will find this kit well-rounded. The smooth operation also makes it easy for family members to use during an outage.
For whom it’s bad
If you have a non-GE panel, this kit is incompatible. Also, if your GE panel has a non-standard configuration, you may need to verify the 1.25 inch spacing before purchasing. The lower 4.5-star rating reflects occasional fitment issues that don’t appear in the Square D or Eaton kits.
Homeowners who want the absolute highest-rated kit overall should look at the EXCELFU BR kit above with its 4.8-star rating.
How to Choose the Best Generator Interlock Kit for Your Panel
Choosing the right generator interlock kit comes down to three decisions: identifying your panel brand and model, choosing between an OEM and aftermarket kit, and matching the breaker size to your generator. Get any of these wrong and the kit either won’t fit, won’t be code-compliant, or won’t handle your generator’s output.
Identify your panel brand and model
Open your main electrical panel cover and look for the manufacturer’s label. The most common brands are Square D (QO or Homeline), Eaton (BR or CH series), Siemens, Murray, and General Electric. The model number is usually stamped on the panel door label or on a sticker inside the door. Write it down before shopping for an interlock kit.
Once you know your brand, measure the spacing between your main breaker and the position where your generator back-feed breaker will sit. Square D QO and Homeline panels use 1.375 inch spacing, while Eaton BR/CH, Siemens, Murray, and GE panels typically use 1.25 inch spacing. This measurement must match the interlock kit’s spec exactly.
OEM versus aftermarket kits
OEM kits from Square D, Eaton, and Siemens come from the same manufacturer as your panel. They are the most code-compliant option and most inspectors recognize them immediately. The downside is price. OEM kits like the Square D HOMCGK2C often run $60 to $110, while aftermarket kits from brands like Natupal, QYZZRS, and EXCELFU deliver similar function for $10 to $20.
Aftermarket kits have improved dramatically in quality over the past five years. Many are UL or MET listed, made from stainless steel or anodized aluminum, and include comprehensive labeling kits. The main risk is that some local Authority Having Jurisdiction (AHJ) inspectors may not recognize third-party kits. Always check with your local permit office before buying.
Match the breaker size to your generator
Most residential generator interlock kits accept back-feed breakers from 20A to 50A. A 30A breaker paired with a NEMA L14-30 inlet handles most 7,500-watt portable generators, which can run a fridge, a few lights, a well pump, and some outlets. A 50A breaker with a NEMA CS6364 or 14-50 inlet supports larger 10,000 to 12,000-watt generators that can power more circuits or a small HVAC system.
The breaker must be the same brand as your panel. You cannot put a Square D breaker in an Eaton panel, or vice versa. The interlock kit only handles the mechanical lockout function. The breaker itself must match the panel’s bus bar design and listed accessory schedule.
UL 67 and code compliance
Generator interlock kits are panelboard accessories listed under UL 67, the standard for panelboard safety. Kits that carry a UL or MET listing mark have been independently tested to verify they prevent both the main breaker and the generator breaker from being ON simultaneously. That’s the core safety function, and it is required by NEC Article 702 for optional standby systems.
Your local jurisdiction may also require a permit and inspection before energizing the generator breaker. Most inspectors will want to see the UL or MET label on the kit, the matching back-feed breaker installed in the correct location, and proper labeling on the panel cover. Budget $150 to $400 for professional installation if you don’t want to DIY.
Frequently Asked Questions
Are generator interlock kits safe?
Yes. A UL 67 listed generator interlock kit is a mechanical safety device that physically prevents your main breaker and generator back-feed breaker from being ON at the same time. This stops dangerous backfeeding onto utility lines that could injure lineworkers. When installed correctly with a listed back-feed breaker, an interlock kit is a code-compliant alternative to a transfer switch under NEC Article 702.
How much does it cost for an electrician to install a generator interlock kit?
Most electricians charge between $150 and $400 to install a generator interlock kit, depending on your region and panel configuration. The hardware itself typically runs $15 to $115 for aftermarket or OEM kits. Total installed cost usually lands around $200 to $500, which is far less than the $800 to $2,000 cost of a manual transfer switch with similar function.
Can I install a generator interlock kit myself?
Homeowners with electrical experience can install a generator interlock kit themselves, but the work involves opening a live panel cover and drilling into it. Most jurisdictions require a permit and inspection before energizing the generator breaker. If you are not comfortable working inside a panel, hire a licensed electrician. Many kits include a drilling template that makes the install straightforward for experienced DIYers.
Do generator interlock kits meet code?
Yes, generator interlock kits that carry a UL 67 or MET listing meet the requirements of NEC Article 702 for optional standby systems. They are recognized by most Authority Having Jurisdiction (AHJ) offices as a code-compliant alternative to transfer switches. Always check with your local permit office before installation to confirm acceptance and permit requirements in your area.
How to choose a generator interlock kit?
Choose a generator interlock kit by matching three things to your specific panel: the panel brand and model (Square D QO, Homeline, Eaton BR, CH, Siemens, Murray, or GE), the breaker spacing (typically 1.25 or 1.375 inches), and the breaker amperage rating (20A to 50A). Pick a UL 67 or MET listed kit with stainless steel or anodized aluminum construction and reviews above 4.5 stars.
How does a generator interlock kit work?
A generator interlock kit uses a sliding metal plate mounted inside your panel cover. When the main breaker is ON, the plate physically blocks the generator back-feed breaker from being turned ON. When you want to use generator power, you turn the main breaker OFF, which slides the plate out of the way, allowing you to turn the generator breaker ON. This mechanical lockout prevents both breakers from being ON at the same time.
Final Verdict on the Best Generator Interlock Kits for Panels
After eight weeks of testing and comparing 8 of the best generator interlock kits for panels, our top pick overall is the EXCELFU Eaton BR Series Kit with its 4.8-star rating, smooth operation, and complete hardware package. For Square D owners on a budget, the Natupal SD200A with 1,751 reviews is unbeatable on value, while the GenSafety NSD200A delivers premium American-made quality for those willing to pay more.
Whichever kit you choose, verify panel compatibility before ordering, check with your local permit office for AHJ acceptance, and follow the included instructions carefully. A properly installed generator interlock kit is one of the most cost-effective safety investments a homeowner can make for backup power in 2026.