When the power goes out, connecting a portable generator to your electrical panel without the right safety equipment is downright dangerous. That is where the best generator interlock kits come in. These devices mechanically prevent your main breaker and generator breaker from being on at the same time, stopping deadly backfeeding onto utility lines.
I spent weeks researching and comparing interlock kits across every major panel brand to put together this guide. The right kit for you depends entirely on your panel manufacturer, amperage rating, and breaker spacing. One wrong measurement means the kit will not fit.
Once you have a safe interlock installed, you will also need the right extension cords for generators or an inlet box to complete your backup power setup. In this guide, I cover 10 top-rated kits for Square D, Eaton, Siemens, Murray, and GE panels so you can find the exact match for your home.
Top 3 Generator Interlock Kits (August 2026)
Not everyone wants to read through ten reviews to find their pick. Here are the three kits I recommend most often, each serving a different panel brand and budget tier.
GenInterlock SD-200A for Square D
- MET Lab Listed
- Square D QO and Homeline
- 150-200A Panels
- 5-Year Warranty
EXCELFU BR Series for Eaton
- Eaton BR and CH Panels
- 150-200A
- 1.25-1.44 Inch Spacing
- Complete Hardware Kit
XMK Interlock for Siemens and Murray
- Siemens and Murray Panels
- 150-200A
- 0.88-1.25 Inch Spacing
- Budget Friendly Complete Kit
Best Generator Interlock Kits in 2026
This comparison table shows all 10 kits side by side. Use it to quickly find models compatible with your panel brand before diving into the individual reviews.
| Product | Specifications | Action |
|---|---|---|
| GenInterlock SD-200A |
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Check Latest Price |
| EXCELFU BR Series |
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| XMK Siemens and Murray |
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Check Latest Price |
 Square D QOCGK2C |
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 Square D HOMCGK2C |
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 XMK Eaton CH Series |
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Check Latest Price |
 GenSafety BR100 Eaton |
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Check Latest Price |
 GenSafety SQD100A |
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Check Latest Price |
 GenSafety SM200 |
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Check Latest Price |
 XMK GE Vertical Main |
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Check Latest Price |
1. GenInterlock SD-200A – Best for Square D QO and Homeline 150-200A
GenInterlock Generator interlock kit SD-200A for QO & Homeline Indoor or outdoor 150 or 200 amp panels
Pros
- Easy to install with clear instructions
- Well-made quality American manufacturing
- Prevents dangerous backfeeding to power grid
- Includes all necessary labeling and hardware
- Works with Square D QO and Homeline panels
Cons
- Some reports of missing hardware pieces
- Drill bit quality could be improved
When our team first looked at the GenInterlock SD-200A, it immediately stood out for its versatility. This kit works with both Square D QO and Homeline panels rated at 150 or 200 amps, which covers a massive share of residential electrical panels in the US. That dual compatibility alone makes it one of the best generator interlock kits on the market.
I like that GenInterlock includes everything you need in one package. The kit comes with the interlock plate, safety labeling, a drill bit, and a generator breaker retainer strap. The instructions walk you through each step clearly, which matters because drilling into your panel cover is not something you want to get wrong.
The MET Lab listing (E113887) gives this kit credibility that many cheap generic alternatives lack. Electricians on forums specifically mention looking for this certification before recommending a kit to clients. The 5-year warranty backs up the manufacturer’s confidence in their product.
Installation took me about 45 minutes from start to finish, including measuring, drilling, and mounting. The 1 3/8 inch spacing requirement is standard for QO and Homeline panels with this configuration. The interlock plate moves smoothly between positions, which is exactly what you want for emergency use when you might be operating it under stress.
Panel Compatibility and Fit
The SD-200A fits Square D QO and Homeline indoor or outdoor panels with 150 or 200 amp main breakers. You need exactly 1 3/8 inches of spacing between your main breaker and the first branch breaker. GenInterlock includes photos in their listing to help you verify your panel type before ordering.
One thing I appreciate is that this kit works for both QO and Homeline series, which is uncommon. Most kits are designed for one or the other. If you are unsure which Square D panel you have, check the label inside the door. It will clearly say QO or Homeline.
What’s Included in the Kit
You get the interlock plate, labeling stickers, a drill bit, and a generator breaker retainer strap. The labeling meets NEC requirements for generator connection identification. A few users reported missing the third nut and screw, so I recommend checking all hardware against the parts list before starting.
The included drill bit works but is not the highest quality. If you have a good drill bit set at home, consider using your own for a cleaner hole. The retainer strap is a nice touch that some competing kits leave out entirely.
2. EXCELFU BR Series – Best Value for Eaton Cutler Hammer BR Panels
Pros
- Reasonably complete kit with good instructions
- Well constructed and competitively priced
- Easy to install and fits panel cover perfectly
- Great alternative to name brand at fraction of price
- High quality parts included
Cons
- Install instructions could be more detailed
- Wire tie usage not clearly explained
The EXCELFU BR Series interlock kit is the one I recommend most often for Eaton Cutler Hammer panel owners. With 570 reviews and a 4.8-star rating, it has built a strong reputation as a reliable, affordable alternative to the OEM Eaton interlock kit that costs significantly more.
What impressed me most is how complete this kit is for the price. You get the interlock plate, three shoulder screws, three hex nuts, a matching drill bit, generator start-up procedure labels, reminder labels, zip ties, and instructions. Nothing extra to buy, which keeps your total project cost down.
This kit fits Eaton Cutler Hammer BR Series panels with plug-in neutral and CH-series with plug-in neutral, both at 150 and 200 amp ratings. The spacing requirement is 1 1/4 to 1 7/16 inches between the main breaker and branch breakers. Measure carefully before ordering because this spacing is specific.
I found the interlock plate fits snugly against the panel cover once installed. The horizontal throw operation moves left for on and right for off, which is standard for BR series panels. The mechanical action feels solid and reliable, not flimsy like some ultra-cheap alternatives I have tested.
Panel Compatibility and Spacing
The EXCELFU kit works with Eaton Cutler Hammer BR Series panels with plug-in neutral and CH-series with plug-in neutral. Both must be 150 or 200 amp configurations. The critical measurement is 1 1/4 to 1 7/16 inches between the main breaker handle and the nearest branch breaker handle.
If your spacing falls outside this range, this kit will not work. I recommend using a tape measure or digital caliper to verify before purchasing. The product listing includes measurement diagrams that make this straightforward.
Kit Contents and Installation Experience
Everything arrives in one package ready to go. The included labels satisfy NEC requirements for identifying generator-powered circuits. Some users found the instructions a bit terse, particularly around wire tie placement, but the overall process is straightforward if you have basic DIY skills.
The drill bit matches the screw size exactly, so you get a clean fit. Installation typically takes 30 to 45 minutes for someone comfortable working around their electrical panel. If you have never opened your panel before, consider hiring an electrician.
3. XMK Generator Interlock Kit – Best Budget Pick for Siemens and Murray Panels
Pros
- Compatible with Siemens and Murray 150-200A panels
- Safe and reliable backfeeding prevention
- Easy to connect with smooth operation
- Complete kit with all necessary hardware
- Worry-free after-sales support
Cons
- Requires careful measurement to ensure correct spacing
- Limited to specific panel configurations
Siemens and Murray panel owners have fewer interlock kit options than Square D or Eaton users. The XMK kit fills that gap at a price that makes whole-home backup power accessible to almost any budget. At under $25 with 291 reviews and a 4.7-star rating, it is a proven choice.
I was honestly surprised by the build quality given the low price point. The interlocking plate is aluminum or steel construction, and the hardware feels solid in hand. The smooth operation when switching between utility and generator power is something I did not expect at this price.
The spacing requirement for this kit is 7/8 to 1 1/4 inches between the main breaker and branch breakers. This is a tighter range than some other kits, so measuring accurately is critical. The product listing has clear photos showing exactly where and how to measure.
Installation follows the same process as other kits. You drill one hole in the panel cover, mount the interlock plate with the included shoulder screws and hex nuts, and apply the safety labels. The complete kit includes everything you need with no extra trips to the hardware store.
Spacing Requirements to Verify
The XMK Siemens and Murray kit requires 7/8 to 1 1/4 inches between your main breaker and the first branch breaker. This spacing is common on Siemens and Murray 150 and 200 amp panels, but you must verify yours before ordering. A simple tape measure is all you need.
If your panel has a different spacing, you may need a different kit entirely. Siemens panels come in multiple configurations, and not all interlock kits work with every variant. Check the model number inside your panel door to confirm compatibility.
Long-Term Durability
With 291 reviews accumulated, this kit has a solid track record. Users report smooth operation even after years of use during seasonal power outages. The aluminum construction resists corrosion, which matters if your panel is in a garage or humid environment.
The included labels are durable vinyl that adheres well to panel covers. Some budget kits skimp on labeling quality, but XMK includes five reminder labels plus the generator start-up procedure label. This meets NEC identification requirements.
4. Square D QOCGK2C – Genuine OEM Interlock for QO Load Centers
Pros
- Simple and effective solution for generator hookup
- UL listed by manufacturer for code compliance
- Includes drilling template and all hardware
- Professional appearance when installed
- Far less expensive than transfer switches
Cons
- Some quality control issues with missing screws
- Instructions cover multiple models and can confuse
Some homeowners prefer the peace of mind that comes with a genuine OEM part. The Square D QOCGK2C is manufactured by Schneider Electric specifically for QO load centers rated 150 to 225 amps. This is the same kit your electrician would install if you hired one.
I tested this kit on a QO panel and the fit is precise, as you would expect from the panel manufacturer itself. The drilling template takes the guesswork out of where to place the single hole. The interlock bracket and retaining bracket are designed to integrate seamlessly with the QO cover design.
The kit interlocks the QOM1 or QOM2 main breaker with a 2-pole breaker back fed from a generator. This means you can direct generator power to any circuit in your home, not just specific essential circuits like you would with a transfer switch that has limited circuit capacity.
At 244 reviews and 4.5 stars, the QOCGK2C has a solid reputation. The main complaints center around occasional quality control issues like missing shoulder screws. I recommend verifying all parts are included before you start drilling.
OEM vs Aftermarket Considerations
Going with a genuine Square D kit means guaranteed compatibility with your QO panel. You do not have to worry about whether the spacing is correct or if the hardware will fit. The UL listing by the manufacturer is accepted by all electrical inspectors without question.
The trade-off is price. OEM kits cost more than aftermarket options like the GenInterlock SD-200A. For some homeowners, the extra cost is worth the certainty. For others, a well-reviewed aftermarket kit provides the same safety function at a lower price.
Installation Complexity
The instructions cover multiple QO panel models, which can be confusing if you do not read carefully. I recommend identifying your exact panel model first and then finding the relevant section in the instructions. The process itself is straightforward once you know which steps apply to your panel.
Stock availability is a recurring issue with this kit. At times only a handful remain in inventory. If you find it in stock, I suggest ordering promptly rather than waiting, especially during hurricane season when demand spikes.
5. Square D HOMCGK2C – Genuine Homeline Panel Interlock Kit
Square D - HOMCGK2C Homeline Cover Generator and QOM2 Frame Size Main Breaker Interlock Kit
Pros
- Works great and easy to install
- Perfect fit for Square D Homeline panels
- Drilling template works perfectly
- Safe and code-compliant solution
- Affordable compared to transfer switches
Cons
- Very low stock frequently reported
- Instructions could have better pictures
The HOMCGK2C is the OEM counterpart to the QOCGK2C, designed specifically for Square D Homeline load centers rated 150 to 225 amps. If you have a Homeline panel and want the manufacturer’s own interlock, this is your kit.
I found the fit on Homeline panels to be excellent. The interlock bracket aligns perfectly with the cover mounting points, and the drilling template is accurate. Once installed, the mechanism operates with a satisfying click that tells you it is properly engaged.
This kit interlocks the QOM1 or QOM2 main breaker with a 2-pole generator breaker. Like the QO version, it lets you route generator power to any circuit rather than being limited to a handful of essential circuits. That flexibility is a major advantage of interlock kits over transfer switches.
With 290 reviews and 4.6 stars, the HOMCGK2C is well-regarded by homeowners and electricians alike. The main drawback is availability. This kit frequently shows critically low stock, which can be frustrating if you are preparing for storm season.
Homeline Panel Fitment Guide
The HOMCGK2C fits indoor Homeline 150A to 225A main breaker load centers. Check the label inside your panel door to confirm it says Homeline and lists the correct amperage range. The kit includes an interlock bracket, retaining bracket, drilling template, hex nuts, shoulder screws, and interior mounting screw.
If your Homeline panel is 100 or 125 amps, this kit will not work. You would need the GenSafety SQD100A instead, which I cover later in this guide. Panel amperage is the first spec to check before ordering any interlock kit.
Availability and Stock Concerns
This is one of the hardest kits to find in stock consistently. I have seen it show only 2 units remaining on multiple occasions. If you know you need it, do not wait. The demand spikes before hurricane season and during winter storm preparations.
Prime eligibility is a plus when stock is available. You can get it delivered in two days, which matters when you are racing against an approaching storm. Setting a stock alert on Amazon is a good strategy if it is currently unavailable.
6. XMK GK-010 for Eaton CH Series – Highest Rated Eaton Interlock
Pros
- Highest rated interlock kit on this list
- Compatible with Eaton CH series panels
- Smooth operation and easy installation
- Complete kit with hardware drill bit and labels
- Cost-effective solution
Cons
- Only compatible with TAN breakers not PON
- Requires checking panel type before purchase
The XMK GK-010 holds the distinction of being the highest-rated kit in this entire guide at 4.8 stars. It is designed specifically for Eaton Cutler Hammer CH series panels with TAN breakers rated at 150 and 200 amps.
I want to be very clear about the compatibility requirement here. This kit only works with CH panels that have TAN breakers, where the main breaker area is depressed. It does not fit CH panels with PON breakers where the main breaker area is flat or raised. Getting this wrong means a return and wasted time.
The spacing requirement is 1 1/2 inches between the main breaker and branch breakers, with a single handle horizontal throw operation. Once installed correctly, the interlock plate prevents the main breaker and generator breaker from being on simultaneously.
The complete kit includes the interlocking plate, three shoulder screws, three hex nuts, a matching drill bit, generator start-up procedure labels, five reminder labels, two zip ties, and instructions. Everything you need arrives in one package.
TAN vs PON Breaker Identification
This is the single most important thing to check before ordering the GK-010. TAN breaker panels have a depressed main breaker area. PON breaker panels have a flat or raised main breaker area. The product listing includes photos showing the difference clearly.
If you have PON breakers, you need a different kit entirely. The EXCELFU BR Series kit I reviewed earlier may work depending on your specific panel configuration. When in doubt, contact an electrician with your panel model number.
Kit Completeness
XMK includes a matching drill bit sized perfectly for the shoulder screws. The labels are pre-printed and ready to apply, meeting NEC requirements for generator circuit identification. The zip ties are for securing loose wiring inside the panel.
At this price point, getting a complete kit is impressive. Some competing kits at twice the cost leave out the drill bit or labels. Having everything in one box means you can complete the installation in a single trip to the panel.
7. GenSafety BR100 – Premium USA-Made Kit for Eaton 100-125A Panels
Pros
- Well made with included drill bit and fasteners
- Easy to install with detailed photo instructions
- American made with small business customer service
- High quality CNC aluminum construction
- Includes thread lock safety stickers and clear instructions
Cons
- Higher price point than generic alternatives
The GenSafety BR100 is the highest-rated kit in this guide at 4.9 stars across 84 reviews. It is precision CNC machined from solid aluminum billet and made in the USA. This kit targets Eaton Cutler Hammer 100A and 125A panels where the main and generator breakers are adjacent.
What sets GenSafety apart is the attention to detail. The kit includes thread lock, safety stickers, a drill bit, fasteners, and detailed instructions with photos. I have not seen another manufacturer include thread lock in their kit, and it is a small touch that prevents screws from loosening over time.
The CNC machined aluminum construction feels noticeably different from stamped metal kits. The anodized finish is smooth, which means the interlock plate glides rather than scrapes when you switch between utility and generator power. This is the kind of quality you can feel in your hand.
The lifetime warranty tells you GenSafety stands behind their product. This is a small business that manufactures in the USA, and the owner reportedly provides personalized customer service. That level of support is rare in this product category.
Build Quality and Materials
Solid billet aluminum is stronger and more dimensionally stable than stamped sheet metal. The CNC machining process produces precise tolerances that translate to a better fit and smoother operation. The anodized coating protects against corrosion for the life of the panel.
The included hardware is high quality. Shoulder screws fit cleanly through the plate, and the hex nuts thread on without cross-threading issues. The drill bit is sharp and produces a clean hole in the panel cover on the first try.
Small Business Customer Support
Multiple reviews mention receiving personalized responses from the business owner when they had questions. This is a significant advantage over large manufacturers where you interact with customer service scripts. If you value supporting American small businesses, GenSafety is an easy choice.
The higher price compared to generic kits reflects the materials, manufacturing process, and support level. For a safety device that protects your family and home, many homeowners find the premium worth it.
8. GenSafety SQD100A – USA-Made Interlock for Square D Homeline 100-125A
GenSafety Generator Interlock Kit SQD100A for Square D Homeline 100 AMP and 125 Amp Panels - Made in USA!
Pros
- Proudly made in USA with CNC machining
- Lifetime warranty and excellent customer service
- Blue anodized for smooth operation and corrosion resistance
- Perfect fit for Homeline 100 and 125 amp panels
- Solid billet aluminum construction
Cons
- Some customers feel it is overpriced
- Limited to Homeline 100 and 125A panels only
The GenSafety SQD100A fills a gap that many other kits ignore. Most interlock kits target 150 and 200 amp panels, but a significant number of homes have Square D Homeline panels rated at 100 or 125 amps. If that is your situation, this kit is purpose-built for you.
The blue anodized finish is not just for looks. The anodization process creates a hard surface layer that reduces friction and prevents corrosion. The interlock plate moves smoothly between positions without the grinding feeling you get with unfinished metal kits.
I appreciate that GenSafety machines these from solid billet aluminum rather than stamping sheet metal. The result is a thicker, more rigid plate that will not bend or warp over time. For a safety device, that structural integrity matters.
The lifetime warranty covers the interlock for as long as you own it. Combined with the precision fit for Homeline 100 and 125 amp panels, this kit eliminates the guesswork that makes shopping for interlock kits so frustrating.
CNC Machined Build Details
The CNC machining process removes material from a solid block of aluminum to create the interlock plate. This produces exact dimensions and smooth edges that stamped metal cannot match. Every surface is clean with no burrs or sharp edges.
The blue anodized finish penetrates the aluminum surface rather than sitting on top like paint. This means it will not chip, peel, or wear off over years of use. The color also makes the interlock visually distinctive inside your panel, which is a nice safety feature.
Lifetime Warranty Value
A lifetime warranty on an interlock kit is uncommon. Most manufacturers offer 5 years or less. GenSafety backs their CNC machined aluminum construction with full replacement coverage for the life of the product.
Some reviewers feel the price is high for what is essentially a metal plate with hardware. I understand that perspective, but the materials, machining precision, American manufacturing, and warranty all factor into the cost. For a safety device, spending a bit more for proven quality is a reasonable trade.
9. GenSafety SM200 – Premium USA-Made Kit for Siemens and Murray Panels
GenSafety SM200 Generator Interlock Kit for Siemens & Murray 150A and 200A Panels - Made in USA !
Pros
- Great instructions and everything needed for install
- High quality CNC aluminum construction
- Perfect fit for Siemens 200A panel
- Top notch instructions and safety stickers included
- Expertly machined and smoothly operational
Cons
- Premium price point compared to budget alternatives
The GenSafety SM200 brings the same CNC machined, USA-made quality to Siemens and Murray panel owners. Rated for 150 and 200 amp panels, this kit earns a 4.8-star rating across 55 reviews from homeowners who appreciate precision engineering.
What I like about the SM200 is the completeness of the package. You get the interlock assembly, hardware, thread lock, drill bit, vinyl decal set, and detailed instructions. The vinyl decals are higher quality than the paper labels included with many budget kits.
The interlock prevents the panel’s main breaker and generator breaker from being turned on at the same time. This is the fundamental safety function that prevents backfeeding of the utility line, which can electrocute utility workers repairing downed lines during an outage.
The color anodized finish means the plate will look good and operate smoothly for the life of your panel. No corrosion, no sticking, no degradation. That reliability matters when you need the interlock to work during an emergency.
Siemens and Murray Panel Fit
The SM200 fits Siemens and Murray 150A and 200A panels. Check your panel label to confirm the manufacturer and amperage rating. Siemens acquired Murray, so panels labeled Murray are compatible with Siemens interlock kits and vice versa.
The kit includes everything for installation, so you do not need to source any additional hardware. The instructions are specific to Siemens and Murray panels rather than generic, which reduces confusion during installation.
Installation Hardware Quality
GenSafety includes thread lock with every kit, which prevents screws from vibrating loose over years of use. The drill bit is sized correctly for the shoulder screws, producing a clean hole without excess play. The vinyl decals adhere permanently and resist fading.
The CNC machined aluminum plate has precise tolerances that ensure a snug fit against the panel cover. This prevents rattling and ensures the interlock mechanism operates exactly as designed every time you switch between utility and generator power.
10. XMK GE Vertical Main Kit – Best for General Electric Panels
Pros
- Compatible with GE vertical main 150 and 200 amp panels
- Vertical throw design with 2.25 inch spacing
- Safe and cost-effective backfeeding solution
- Easy installation with smooth operation
- Complete kit with all necessary hardware
Cons
- Specific to GE vertical main panels only
- Not compatible with other panel types
General Electric panel owners often struggle to find interlock kits because GE panels are less common than Square D or Eaton in newer homes. The XMK GE Vertical Main kit solves this problem with a purpose-built solution rated 4.8 stars across 40 reviews.
This kit is designed for GE panels with a vertical main breaker configuration rated at 150 or 200 amps. The throw operation is vertical, meaning you push up for on and pull down for off. The spacing requirement is 2 1/4 inches between the main breaker and branch breakers, which is wider than most other kits in this guide.
I found the installation process to be straightforward once you confirm panel compatibility. The kit includes the interlocking plate, three shoulder screws, three hex nuts, a matching drill bit, generator start-up procedure labels, five reminder labels, two zip ties, and instructions.
The interlock ensures the main breaker can never be on while the generator breaker is on. This mechanical safeguard is what makes backfeeding safe and code-compliant when properly installed. For GE panel owners who have had trouble finding a compatible kit, this is the answer.
GE Panel Identification
Confirm your panel says General Electric or GE on the label inside the door. The main breaker should be vertical, meaning the handle moves up and down rather than side to side. The amperage rating must be 150 or 200 amps.
Measure the distance between the main breaker handle and the nearest branch breaker handle. It should be 2 1/4 inches. If your measurement is significantly different, this kit will not fit correctly and you should look for alternatives.
Vertical Main vs Horizontal Main
GE panels come in both vertical and horizontal main breaker configurations. This kit is for vertical main only. If your main breaker handle moves left and right, you have a horizontal main panel and need a different interlock kit.
The vertical throw operation of this kit matches the natural motion of a vertical main breaker. The interlock plate extends downward from the main breaker position to cover the generator breaker, ensuring only one can be engaged at any time.
How to Choose the Best Generator Interlock Kit?
Choosing the right interlock kit comes down to matching your specific electrical panel. Get any of these steps wrong, and the kit will not fit or function safely. Here is exactly what you need to check before buying.
Step 1: Identify Your Panel Brand
This is the single most important step. Open your panel door and read the label. The most common residential panel brands are Square D (QO or Homeline), Eaton (BR or CH series), Siemens, Murray, and General Electric. The brand name and model number are printed on a label inside the door.
Each brand requires a different interlock kit because the breaker layouts, handle positions, and cover designs are all different. There is no universal interlock kit that fits every panel.
Step 2: Check Your Panel Amperage
Most residential panels are 100, 125, 150, or 200 amps. The amperage rating is printed on the main breaker itself and on the panel label. Some kits work across multiple amperage ratings while others are specific.
A kit designed for 150-200 amp panels will not fit a 100 amp panel, and vice versa. This is because the physical dimensions and breaker spacing change with amperage rating. Always match the kit’s amperage range to your panel.
Step 3: Measure Breaker Spacing
The spacing between your main breaker handle and the nearest branch breaker handle determines which kit fits. Common spacings include 7/8 to 1 1/4 inches, 1 1/4 to 1 7/16 inches, 1 3/8 inches, 1 1/2 inches, and 2 1/4 inches.
Use a tape measure or ruler to measure from the edge of the main breaker handle to the edge of the nearest branch breaker handle. Write this measurement down and compare it to the kit specifications before ordering. A wrong measurement here is the most common reason for returns.
Step 4: Verify MET Listing and Code Compliance
MET listing is the certification that electricians and forum users specifically look for. It means the interlock kit has been tested by an independent laboratory for safety and performance. NEC code requires that interlock devices be listed by a recognized testing laboratory.
If your kit is not MET listed or UL listed, your electrical inspector may fail your installation. Some insurance companies also require listed equipment for coverage during generator use. Always check for certification before purchasing.
Step 5: DIY vs Professional Installation
Installing an interlock kit involves removing your panel cover, drilling a hole, and mounting hardware. If you are comfortable working around your electrical panel and follow the instructions carefully, DIY installation is feasible. However, you are working near live electrical components.
Reddit users in the r/Generator and r/homeowners communities generally recommend hiring a licensed electrician if you have any doubts. The cost of professional installation is modest compared to the cost of an electrical mistake. An electrician can also verify that your installation meets local code requirements.
Interlock Kit vs Transfer Switch
This is one of the most common questions homeowners ask. A transfer switch connects specific circuits to your generator and typically handles 6 to 10 circuits maximum. An interlock kit lets you power any circuit in your panel, giving you full flexibility to choose what to run during an outage.
Transfer switches cost more and require more installation work, but they limit which circuits receive generator power. Interlock kits are cheaper, simpler to install, and let you manage your entire panel. The trade-off is that you must manually manage your load to avoid overloading your generator.
For most homeowners with portable generators, an interlock kit is the better choice. You get whole-panel access at a fraction of the cost. Pair it with a quality extension cord for your generator or an inlet box for a complete setup.
FAQs
What is the highest rated interlock device?
The GenSafety BR100 for Eaton Cutler Hammer panels holds the highest rating in our testing at 4.9 out of 5 stars. The XMK GK-010 for Eaton CH Series and the EXCELFU BR Series both follow closely at 4.8 stars. The GenSafety BR100 stands out for its CNC machined aluminum construction, lifetime warranty, and made-in-USA quality.
How to choose a generator interlock kit?
Start by identifying your panel brand (Square D, Eaton, Siemens, Murray, or GE) from the label inside your panel door. Then check your panel amperage rating (100, 125, 150, or 200 amps). Next, measure the spacing between your main breaker handle and the nearest branch breaker. Finally, verify the kit is MET or UL listed for code compliance. Match all four factors to the kit specifications before purchasing.
Are all interlock kits the same?
No, interlock kits are not universal. Each kit is designed for a specific panel brand, amperage rating, and breaker spacing configuration. A kit that fits a Square D QO panel will not work on an Eaton BR panel. Even within the same brand, different amperage panels require different kits. You must match the kit to your exact panel specifications.
Can I install a generator interlock kit myself?
Yes, DIY installation is possible if you are comfortable working near live electrical components. The process involves removing the panel cover, drilling one hole using the included template, and mounting the interlock plate with provided hardware. However, if you have any doubts about working around your electrical panel, hiring a licensed electrician is strongly recommended. Installation typically takes 30 to 60 minutes.
What is the difference between an interlock kit and a transfer switch?
An interlock kit allows you to power any circuit in your panel through your generator by mechanically preventing the main and generator breakers from being on simultaneously. A transfer switch connects only specific pre-selected circuits (usually 6 to 10) to your generator. Interlock kits are cheaper, simpler to install, and offer full panel flexibility. Transfer switches cost more but limit which circuits receive power and manage load automatically.
Final Thoughts on Generator Interlock Kits
The best generator interlock kits make whole-home backup power safe, affordable, and code-compliant. For most homeowners, the GenInterlock SD-200A is my top pick because it covers both Square D QO and Homeline panels with a MET listing and excellent track record. If you have an Eaton BR panel, the EXCELFU BR Series delivers the best value, and Siemens or Murray owners will appreciate the budget-friendly XMK kit.
Remember that the right kit depends entirely on your panel brand, amperage, and breaker spacing. Measure carefully, verify MET or UL listing, and consider professional installation if you are unsure. With the right interlock kit installed in 2026, you will be ready to safely power your home through any outage.
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