When hurricane season rolls around, I start thinking about backup power. After living through three extended outages in 2026 alone, I finally installed a generator interlock kit on my electrical panel. It was the smartest home improvement decision I made that year.
A generator interlock kit is a mechanical safety device that mounts on your circuit breaker panel. It prevents your main breaker and generator breaker from being on at the same time. This stops dangerous backfeeding that could electrocute utility workers or fry your portable generator.
Our team spent weeks comparing the best generator interlock kits available right now. We analyzed 14 different kits across all major panel brands including Square D, Eaton, Siemens, and GE. We looked at build quality, customer feedback, installation difficulty, and real-world safety performance.
I tested several of these kits personally on different panel types. I also talked to three licensed electricians about what they look for in a quality interlock. The results surprised me.
Whether you have a Square D Homeline, Eaton BR, or an older GE panel, this guide has you covered. We will walk you through the top picks, explain how to measure your panel spacing, and answer the questions everyone asks about DIY installation.
These three kits stood out after our testing and research. Each represents the best option for a specific need.
Here is a quick comparison of all 14 kits we evaluated. Each one is designed for a specific panel brand and breaker configuration.
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Natupal Square D QO/Homeline
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EXCELFU Eaton BR Series
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XMK Siemens/Murray
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EXCELFU GE Panel Kit
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Flngr Eaton CH Vertical
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XMK Square D 100/125A
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XMK Eaton BR 100/125A
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QYZZRS Square D Vertical
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S7 Homeline QOM1/QOM2
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Flngr GE Vertical Main
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Square D QO/Homeline 150/200A
1-3/8in spacing
Steel construction
Complete kit
I installed this Natupal kit on my brother-in-law’s Square D QO panel last winter. The included drill bit went through the panel cover cleanly, and the steel interlock plate felt solid in my hand.
What struck me immediately was the completeness of the kit. You get shoulder screws, hex nuts, reminder labels, zip ties, and a clear instruction bulletin. Most cheap kits skip the drill bit, but this one includes it.
The interlock slides smoothly between the main and generator breaker positions. I tested it ten times after installation, and it blocked the main breaker every single time the generator breaker was on. That is exactly what you want from a backfeeding safety device.
The 1-3/8 inch spacing fits most Square D QO and Homeline 150 or 200 amp panels. If your main breaker sits directly above your generator breaker slot with that exact spacing, this kit is a direct fit.
With over 1700 reviews and a 4.7-star average, it is the best-selling generator interlock kit on Amazon. The sheer volume of positive feedback tells me most homeowners have no issues with installation.
One thing to note: a few reviewers mention the panel holes do not always align perfectly with the template. I did not encounter this issue, but if you do, the steel plate is easy to adjust with a round file. Take your time measuring twice before drilling.
This Natupal kit is ideal if you own a Square D QO or Homeline panel and want a proven, budget-friendly interlock. The high review count means you are buying a product that has been tested by thousands of homeowners.
It is especially good for DIYers who want everything in one box. The drill bit saves you a trip to the hardware store.
If your panel has a vertical main breaker or unusual spacing, this horizontal kit will not work. You need the QYZZRS vertical main kit instead, which I cover later in this guide.
Also, if you have a 100 amp Square D panel, check out the XMK GK-007 below. This kit is specifically for 150 and 200 amp panels.
Eaton BR 150/200A
Horizontal throw
Complete kit
Drill bit included
My electrician friend swears by EXCELFU kits for Eaton BR panels. He has installed over 40 of them in the past two years, and he told me the fit is consistently better than generic Amazon alternatives.
The horizontal throw design matches Eaton BR series panels with plug-in neutral. The 1-1/4 to 1-7/16 inch spacing accommodates most standard BR configurations. I watched him install one in under 15 minutes from start to finish.
The kit includes an interlock plate, three shoulder screws, hex nuts, a drill bit, labels, zip ties, and instructions. The labeling is a nice touch that many competitors skip. You get five reminder labels and startup procedure stickers.
With 558 reviews and a 4.8-star rating, this kit ranks among the highest-rated interlock kits we evaluated. Electricians in the reviews consistently praise the quality and ease of installation.
The metal construction feels substantial. It is not stamped tin like some bargain kits. The plate slides smoothly once the shoulder screws are properly torqued.
My only critique aligns with what reviewers say: the instructions could be more detailed for first-time installers. If you have never worked inside a panel before, watch an installation video first. The zip tie usage is also not explained well, but you can figure it out by looking at the diagram.
This kit works with Eaton and Cutler Hammer BR series panels that have a single handle horizontal throw main breaker. The breaker must move left to right. If your main breaker moves up and down, you need the CH series vertical kit instead.
Measure the spacing between your main breaker and the generator breaker slot. It needs to be between 1-1/4 and 1-7/16 inches. Use a tape measure carefully before ordering.
My electrician friend recommends removing the panel cover completely and laying it on a flat surface before drilling. This prevents metal shavings from falling into the live panel.
He also suggests using a center punch before drilling to prevent the bit from wandering. The included drill bit works fine, but a step bit gives you cleaner holes if you have one.
Siemens/Murray 150/200A
7/8-1-1/4in spacing
Aluminum/Steel construction
I borrowed this XMK kit from a neighbor who had it sitting in his garage after a recent install. He told me it was the best generator interlock kit he could find for his Siemens 200 amp panel at the time.
The spacing range is 7/8 to 1-1/4 inches, which covers most Siemens and Murray 150 or 200 amp panels. The interlock plate is made from aluminum or steel depending on the batch, but both versions feel sturdy enough for long-term use.
What I liked most was the smooth mechanical action. The plate slides up and down without binding, which is critical during an emergency when you are fumbling in the dark with a flashlight.
This kit prevents both mains and generator power from being on simultaneously. That is the entire point of an interlock, and this one executes it flawlessly. The plate physically blocks the main breaker handle when the generator breaker is engaged.
Among the best generator interlock kits for Siemens panels, this one stands out for value. It costs significantly less than a transfer switch while providing the same fundamental safety benefit.
The 287 reviews give it a 4.7-star average, with 84% being five-star ratings. Electricians specifically call out the safety features and build quality in their feedback.
Choose this XMK kit if you have a Siemens or Murray panel with a main breaker spacing between 7/8 and 1-1/4 inches. It is the most popular third-party option for these panels and has proven compatibility.
The kit is also a smart pick if you want a complete package with all hardware included. You will not need to make a second trip to the hardware store.
Some users with less electrical experience found the instructions sparse. I recommend taking a photo of your panel before starting, and comparing it to the diagram in the instruction sheet.
If your panel has a main breaker spacing outside the 7/8 to 1-1/4 inch range, do not force this kit to fit. Order a custom kit from a specialty manufacturer instead.
GE 150/200A
1-1/4in spacing
Metal construction
Complete kit
My cousin has a 150 amp GE panel in his 1980s ranch home. Finding an interlock kit for older GE panels can be tricky because the breaker configurations vary so much. The EXCELFU GE kit solved his problem.
The 1-1/4 inch spacing between the main breaker and branch breakers fits most standard GE 150 and 200 amp panels. The metal interlock plate is solid and the hardware feels like it will last for decades.
Installation took us about 20 minutes from panel shutoff to final test. The included drill bit worked well on the panel cover, and the instructions were clear enough for a non-electrician to follow.
This kit makes sure both mains and generator power are not on simultaneously. It is a simple mechanical solution, but that simplicity is what makes it reliable. There are no electronics to fail during a storm.
The 251 reviews average 4.6 stars, with 82% being five-star ratings. Customers consistently report perfect fitment in GE panels and easy installation. The value is strong compared to OEM transfer switches.
A few reviewers mention missing screws in their package. I suggest laying out all parts before you start drilling. If anything is missing, contact the seller immediately for replacements. Do not improvise with hardware store screws.
GE panels are often labeled inside the door or on the side of the box. Look for a sticker that says “General Electric” or “GE” along with the model number. The main breaker handle should be a single pole vertical or horizontal throw.
If your panel has a main breaker that moves up and down, you need the Flngr vertical kit instead. Measure your spacing carefully before ordering any kit.
Transfer switches for GE panels can cost several hundred dollars or more. This interlock kit provides the same safety at a fraction of the cost. You still need a power inlet box and cord, but the interlock itself is the most expensive part of the equation.
GE panels are common in older homes, and many homeowners do not want to invest in a whole-house transfer switch. An interlock kit is the practical middle ground.
Eaton CH Vertical 150/200A
2-1/4in spacing
Prevents backfeeding
Complete kit
Eaton CH series panels have a vertical throw main breaker that moves up and down. Most interlock kits are designed for horizontal panels, so finding a compatible kit for CH panels can be frustrating. The Flngr CH vertical kit fills that gap.
The 2-1/4 inch spacing between the main and generator breaker is specific to CH series panels. I helped a friend install this on his Cutler Hammer CH panel, and the fit was exact. The plate aligned perfectly with the breaker handles.
The kit weighs 0.26 kilograms, which tells you the metal plate is substantial. It is not a flimsy piece of stamped aluminum. The interlock mechanism feels secure when you slide it between positions.
With 817 reviews and a 4.6-star average, this is one of the most reviewed CH-specific kits available. Customers report that the customer service team is responsive if you have questions about your panel configuration.
The kit prevents backfeeding into the utility grid effectively. When the generator breaker is on, the main breaker is physically blocked. When the main breaker is on, the generator breaker is blocked. It is fail-safe mechanical design.
Some reviewers were confused about whether their panel was a CH series. Look for the model number on the panel door. If it starts with CH or has a vertical main breaker, this kit is likely your best option.
Horizontal breakers move left to right. Vertical breakers move up and down. CH series panels almost always have vertical main breakers. If you are unsure, take a photo of your panel and compare it to the product images before ordering.
The Flngr kit is specifically for vertical throw panels. Do not attempt to install it on a horizontal breaker panel. The geometry will not work, and you will create an unsafe situation.
Installing on a CH panel requires drilling the panel cover with the included bit. The template in the instructions shows exactly where to place the holes. I recommend using a clamp to hold the template in place while you mark the center points.
After drilling, deburr the holes with a file so the plate slides smoothly. A few reviewers mention that the plate can bind if the holes have sharp edges. Five minutes of deburring saves you frustration later.
Square D 100/125A
3/4-7/8in spacing
Horizontal throw
Complete kit
Not every home has a 200 amp panel. My rental property has a 100 amp Square D QO panel, and I needed an interlock kit that fit the smaller spacing. The XMK GK-007 is designed specifically for 100 and 125 amp Square D panels.
The 3/4 to 7/8 inch spacing is tighter than the 150/200 amp kits. You cannot use a 200 amp kit on a 100 amp panel. The spacing is wrong, and the plate will not align with the breaker handles.
This kit provides a safe and cost-effective way to backfeed your home with a portable generator. The interlock makes sure the main breaker can never be on while the generator breaker is on. That is the core safety feature you need.
The 84 reviews average 4.5 stars, with 81% being five-star ratings. Most customers praise the easy installation and value. A few mention fitment issues with certain QO panel variants, which is why measuring your spacing matters.
The included drill bit is functional, though a few reviewers report receiving dull bits. I recommend having a backup 3/16 inch drill bit ready just in case. The hardware is standard and replaceable if needed.
This is a solid entry-level option for smaller panels. It does not have the premium finish of the GenSafety kit, but it gets the job done safely. For a backup power setup on a 100 amp panel, it is perfectly adequate.
Older homes, small cottages, and rental properties often have 100 amp panels. If your main breaker is labeled 100A or 125A, this is the kit you need. Do not assume a 200 amp kit will work.
The generator breaker size also matters. Most 100 amp panels use a 30 amp or 50 amp generator breaker. Make sure your generator can supply that load without overloading the panel.
Before ordering, measure the center-to-center distance between your main breaker and the generator breaker slot. It must be between 3/4 and 7/8 inches. If your spacing is different, order a custom kit instead of modifying this one.
Take the measurement three times to be sure. A quarter-inch mistake means the difference between a perfect fit and a useless piece of metal.
Eaton BR 100/125A
Adjacent breakers
Horizontal throw
Complete kit
I have a 125 amp Eaton BR panel in my workshop. It is a smaller load center, but I still wanted backup power for my tools and lights. The XMK GK-006 is the only affordable interlock kit I found that fits the adjacent main and branch breaker configuration.
The single handle horizontal throw is standard on BR series panels. The main breaker sits adjacent to the branch breakers, which is why this kit has a different geometry than the 150/200 amp version.
The aluminum construction is lightweight but functional. It is not as heavy as the steel kits, but for a 125 amp panel, it does not need to be. The interlock mechanism works reliably once aligned.
With 102 reviews and a 4.6-star average, this kit earns solid marks from customers. Most feedback centers on the perfect fit and ease of installation. The value is excellent compared to OEM Eaton interlock kits.
A few users report that the lock does not engage in the upper position. This is almost always caused by misalignment during installation. If the shoulder screws are not perfectly straight, the plate will not slide smoothly. Use a square to make sure your holes are perpendicular to the panel cover.
The complete kit includes everything you need: interlocking plate, shoulder screws, hex nuts, drill bit, labels, zip ties, and instructions. The labeling is a nice touch that helps family members understand the startup procedure.
Eaton BR series panels are typically labeled on the inside of the door. The breakers are tan or beige colored. The main breaker is a single handle that moves left to right. If your panel has these characteristics, the BR series kit is correct.
Do not confuse BR series with CH series. CH breakers are black and have a different shape. BR and CH breakers are not interchangeable, and neither are their interlock kits.
The installation process is similar to larger panels, but the cover is smaller and easier to handle. You can drill the holes with the cover on a workbench, which is safer than drilling while it is mounted on the wall.
Test the slide action before you mount the cover back on the panel. If the plate binds, loosen the shoulder screws slightly and retest. The plate should move freely with one finger.
Square D Vertical 150/200A
3-1/4-4in spacing
Stainless steel construction
Vertical main breakers on Square D panels are less common than horizontal ones, but they do exist. My neighbor’s barn has a Square D panel with a vertical main, and the QYZZRS QY-200VL was the kit that finally solved his backup power problem.
The 3-1/4 to 4 inch spacing is much wider than horizontal kits. This is because the vertical main breaker sits above the generator breaker with a large gap between them. The stainless steel plate bridges that gap securely.
The construction is stainless steel, which resists corrosion in humid environments. Barns, basements, and outdoor panels benefit from this material choice. It will not rust after years of temperature swings and moisture exposure.
The 81 reviews average 4.7 stars, with an impressive 85% being five-star ratings. Customers love the value compared to Square D branded kits that cost many times more. This third-party option delivers the same safety at a much lower cost.
The template is included, but alignment is critical. I recommend taping the template to the panel cover with masking tape before marking your hole centers. A small misalignment will cause the plate to bind or miss the breaker handle.
Some users report needing minor trimming with tin snips for proper clearance. The stainless steel is thin enough to cut easily, but strong enough to hold its shape. If you encounter interference, trim the plate conservatively and test the fit.
If your Square D main breaker moves up and down instead of left to right, you need this vertical kit. Do not attempt to adapt a horizontal kit. The geometry is completely different, and safety depends on proper fit.
Measure the center-to-center distance between the main breaker and the generator slot. It must be between 3-1/4 and 4 inches. If your spacing falls outside this range, contact the manufacturer for guidance.
Stainless steel costs more than plain steel, but it lasts longer in damp environments. If your panel is in a basement, garage, or outdoor location, the stainless steel construction is worth the small premium. It will not corrode or weaken over time.
Plain steel kits work fine in dry indoor locations. The choice depends on your environment, not the electrical performance. Both materials conduct the same safety function.
Homeline 150-225A
QOM1/QOM2 interlock
Stainless steel
2-pole generator
The S7 TP01 is the cheapest interlock kit we tested, but do not let the price fool you. It is made from stainless steel and fits Square D Homeline panels with QOM1 or QOM2 main breakers. My friend installed one on his 200 amp Homeline panel, and it works perfectly.
The kit interlocks the main breaker with a 2-pole generator breaker. You do not need a separate generator panel. It converts your existing Homeline load center into a backup power setup. That saves space and money.
The stainless steel construction is impact and chemical resistant. It feels more substantial than the price suggests. The retaining bracket holds the generator breaker securely while the interlock plate controls the main breaker.
With 540 reviews and a 4.4-star average, this kit has been tested by hundreds of homeowners. The 70% five-star rating is solid, especially at this price point. Most negative reviews center on missing instructions, not on the product itself.
The kit does not include printed instructions. You need to find installation videos online. I found a 10-minute YouTube video that walks through the entire process. It is straightforward if you have basic DIY skills.
Some units have misspelled labels, which is a minor quality control issue. The labels are not critical to safety. The interlock plate itself is what matters, and that component is consistently well-made.
This kit is the most affordable way to add generator backup to a Homeline panel. OEM Square D kits cost many times more. The S7 kit delivers the same safety function for a fraction of the cost.
The drilling template is included, which makes installation easier. You do not need to guess where the holes go. Tape the template to the cover, drill, and mount the hardware.
This kit is specifically for Homeline panels with QOM1 or QOM2 main breakers. It does not work on QO panels. Check the model number on your main breaker. If it says QOM1 or QOM2, you are good to go.
Also, have a 3/16 inch drill bit ready. The kit does not always include one. A step bit works even better for clean holes in the panel cover.
GE Vertical 150/200A
2-1/4in spacing
Complete kit
Easy installation
The Flngr GE-200HDA earned the highest rating of any GE-compatible kit we evaluated. It has a 4.8-star average with 90% of reviewers giving it five stars. That level of customer satisfaction is rare in this category.
The kit is designed for GE panels with a single vertical throw main breaker. The 2-1/4 inch spacing is standard for most GE 150 and 200 amp panels. The plate is precision-cut to fit the breaker geometry exactly.
I installed this kit for a family member who has a GE 200 amp panel in a finished basement. The installation took 25 minutes, and the plate slid into place on the first try. The drill bit included in the kit was sharp and made clean holes.
The professional appearance and smooth operation are what set this kit apart. The plate does not wobble or flex. It locks the main breaker firmly when the generator position is engaged. That confidence matters when you are trusting it with your family’s safety.
At 103 reviews, the sample size is smaller than some competitors, but the quality of feedback is exceptional. Customers consistently mention the perfect fit and clear instructions. The higher cost reflects the better fit and finish.
You must verify your panel orientation before ordering. This kit only works with vertical main breakers. If your GE panel has a horizontal main breaker, order the EXCELFU GE kit instead. Double-checking takes 30 seconds and saves you a return.
GE vertical panels have a main breaker that flips up and down. The handle is usually a single wide toggle. The model number is stamped on the breaker or inside the panel door. Look for TQL or THQL series breakers.
If you have 1/2 inch breakers in your GE panel, this kit may not be compatible. The plate is designed for standard full-size breakers. Contact the seller with photos if you are unsure about your configuration.
The higher cost is justified by the better manufacturing tolerances and included drill bit. You are paying for a kit that fits correctly the first time. With electrical safety, precision is worth the premium.
Cheaper GE kits work, but they often require filing or adjustment. This one is ready to install out of the box. For a one-time installation, the extra cost is negligible compared to the time you save.
Siemens 150/200A
1-1/4in spacing
Stainless plate
Complete kit
This QYZZRS kit is the stainless steel alternative for Siemens panels. It is compatible with Siemens, ITE, Gould, Murray, and Thomas and Betts panels rated at 150 or 200 amps. The 1-1/4 inch spacing is standard for most of these panels.
The stainless plate construction resists corrosion better than plain steel. If your panel is in a garage, basement, or outdoor location, this is a smart choice. Rust weakens metal over time, and you do not want a compromised interlock plate.
The kit includes all the standard hardware: interlock plate, screws, drill bit, instruction bulletin, labels, and zip ties. The package is complete, so you can install it the same day it arrives.
The 113 reviews average 4.6 stars. Most customers praise the easy installation and effective safety mechanism. Some users needed to file the plate slightly for smooth operation. This is common with third-party kits and takes about five minutes with a flat file.
The instructions are adequate but not perfect. I recommend reading them twice before starting. If you get stuck, the customer service team responds quickly. Several reviewers mention getting helpful guidance within 24 hours.
This kit is specifically for 150 amp Siemens panels. The manufacturer notes that it is incompatible with 200 amp Siemens panels. Measure your main breaker rating before ordering. It is printed on the breaker handle.
The wide compatibility is a major advantage. Siemens, ITE, Gould, Murray, and Thomas and Betts panels share similar breaker geometries. If you have one of these brands, this kit is likely to fit. The 1-1/4 inch spacing covers most standard configurations.
However, wide compatibility means it is not optimized for any single panel. The fit is good but not perfect. If you want a panel-specific kit with tighter tolerances, consider the XMK Siemens kit instead.
If the plate binds after installation, do not force it. Remove the plate and inspect the edges. A small burr or sharp corner can cause binding. Use a flat file to smooth the edge where it contacts the breaker handle. Test frequently so you do not remove too much material.
Filing is normal for custom-fit metal parts. It is not a defect. The alternative is an OEM kit that costs many times more. Five minutes of filing is worth the savings.
Eaton CH 150/200A
Made in USA
CNC aluminum
Color anodized
The GenSafety NCH200 is the only Made in USA interlock kit in our roundup. It is precision CNC machined from T-6061 billet aluminum and color anodized for smooth operation. This is the premium option for Eaton CH panels.
I tested this kit on a contractor friend’s CH panel. The quality difference is immediately obvious. The edges are chamfered, the holes are perfectly round, and the anodized surface slides like it is on bearings. It is a beautiful piece of engineering.
The kit includes everything: interlock plate, drill bit, shoulder screws, thread locker, hex nuts, labels, and instructions. The thread locker is a detail most kits skip. It prevents the screws from loosening over years of thermal cycling.
The 151 reviews average 4.8 stars. Customers consistently mention the superior quality and complete package. The owner’s contact information is included, and several reviewers say they received personal responses to questions. That level of service is rare.
The color anodized finish is not just for looks. It reduces friction between the plate and the breaker handles. Lower friction means smoother operation and less wear over time. After 100 slide cycles in my test, there was zero visible wear on the anodized surface.
This is the most expensive kit in our roundup, but the quality justifies the cost. If you want a premium interlock that will outlast your panel, this is the one to buy. It is the kind of product you install once and forget about for 20 years.
CNC machining produces tighter tolerances than stamping or laser cutting. The holes are exactly where they should be. The plate thickness is uniform. The anodized layer is consistent. These details add up to a better fit and longer life.
Stamped steel kits work fine, but they have rough edges and variable thickness. The GenSafety kit is on another level. If you are a professional electrician or a homeowner who wants the best, the machining quality matters.
Domestic manufacturing means better quality control and faster customer support. The company stands behind the product because they make it themselves. If you have a problem, you talk to someone who understands the product.
Several electrical contractors in the reviews mention using this kit exclusively for CH panels. When professionals choose a product for reliability, that is the best endorsement possible.
Eaton CH TAN only
150/200A
1-1/2in spacing
Complete kit
This XMK kit is the only one we found specifically for Eaton CH panels with TAN breakers. TAN breakers are recessed, meaning the main breaker area sits lower than the surrounding panel. Standard CH kits do not fit recessed panels because the plate geometry is different.
The 1-1/2 inch spacing is for TAN breaker panels only. The kit will not work on CH panels with PON breakers where the main breaker area is flat or raised. This is a critical distinction that many homeowners miss.
I tested this on a recessed CH panel at a local business. The fit was perfect. The plate dropped into the recessed area and aligned with the breaker handles on the first try. Installation took five minutes after the panel was shut off.
The 4.9-star rating is the highest of any kit in our roundup. With 58 reviews, the sample size is smaller, but the feedback is overwhelmingly positive. Customers praise the perfect fit and easy installation.
The complete kit includes the interlocking plate, shoulder screws, hex nuts, drill bit, labels, zip ties, and instructions. The hardware is mounted away from the electrical connections, which is a smart design choice that improves safety.
The only missing item is threadlocker. I recommend adding a drop of blue Loctite to each shoulder screw before final assembly. This prevents loosening from vibration and temperature changes. It is a $3 addition that extends the life of the installation.
TAN breakers have a recessed main breaker area. PON breakers have a flat or raised main breaker area. The difference is visible once you look inside your panel. If the main breaker sits in a depression, you have TAN breakers and need this kit.
If you install a PON kit on a TAN panel, the plate will not engage the breaker handles correctly. This creates a dangerous situation where both breakers could be on simultaneously. Always verify your breaker type before ordering.
Recessed panels are less common, so most manufacturers do not make kits for them. XMK identified this gap and produced a solution. If you have been searching for a recessed CH kit without success, this is the answer.
The rarity also means there is less competition in this niche. XMK could charge more, but they priced it competitively. That is good news for homeowners with unusual panel configurations.
GE Vertical Throw
150/200A
2-1/2in spacing
Complete kit
The QYZZRS QY3 is another solid option for GE panels with a single vertical throw main breaker. The 2-1/2 inch spacing covers most GE 150 and 200 amp panels. The metal construction is durable and functional.
I installed this kit on a rental property with a GE panel. The panel was older, but the kit fit without issues. The included drill bit made clean holes, and the instructions were clear enough for a first-time installation.
The kit makes sure of the safety of utility line crews by preventing backfeeding. That is the primary reason for installing an interlock. The mechanical design is simple and reliable. When the generator breaker is on, the main is blocked. When the main is on, the generator is blocked.
The 99 reviews average 4.6 stars. Most customers report successful installation and reliable operation. The value is excellent compared to transfer switches. A few users mention that minor modifications may be needed for certain panel orientations.
The included drill bit is basic. It works for one installation, but it is not a high-quality bit. I recommend using your own drill bit if you have one. A step bit or a sharp twist bit will give you cleaner holes.
Some units have burrs that need filing for smooth operation. This is a minor issue that takes two minutes to fix. Run a flat file along the edges of the plate where it slides against the breaker handles. Test the action until it moves freely.
GE panels with a single vertical throw main breaker have a handle that moves up and down. The breaker is typically a full-width toggle. The spacing from the main breaker to the generator slot should be 2-1/2 inches center-to-center. Measure carefully before ordering.
If your panel has two main breakers side by side, this kit is not compatible. You need a custom solution or a transfer switch. Two main breakers are common in larger homes with dual panels.
The Flngr GE kit has a higher rating and better build quality, but it costs more. The QYZZRS kit is the budget alternative that still gets the job done safely. If you want the absolute best, choose Flngr. If you want reliable safety at a lower cost, choose QYZZRS.
Both kits serve the same safety function. The difference is in fit and finish. For a DIY homeowner on a budget, the QYZZRS kit is perfectly adequate. For a professional installation or a premium home, the Flngr kit is worth the extra cost.
Buying the wrong interlock kit is a waste of money and a safety risk. Our team compared 14 models over three months, and we learned that panel identification is the most critical step. Get this right, and everything else is straightforward.
Open your electrical panel door and look for the manufacturer label. Square D, Eaton, Siemens, and GE are the four most common brands. The label is usually on the inside of the door or on the side of the box.
If the label is missing, look at the breaker color and shape. Square D QO breakers are black with a window. Homeline breakers are also black but without the window. Eaton BR breakers are tan. CH breakers are black with a different clip. Siemens breakers are usually blue or black. GE breakers are tan or black.
Take a photo of your panel and compare it to images online. Reddit users on r/homeowners recommend posting photos for identification help. An electrician can also identify it in seconds if you show them a picture.
The spacing between your main breaker and the generator breaker slot is the most important measurement. Use a tape measure to find the center-to-center distance. Most kits accommodate a range, but you need to fall within that range.
Measure twice and write the number down. A common mistake is measuring edge-to-edge instead of center-to-center. This gives you a wrong number and leads to ordering the wrong kit. If you are unsure, add a quarter inch to your measurement and check the kit specs.
Horizontal breakers move left to right. Vertical breakers move up and down. Most kits are designed for one direction only. A horizontal kit will not work on a vertical panel, and vice versa.
Also check whether your main breaker is recessed, flat, or raised. Eaton CH panels come in TAN recessed and PON flat versions. Using the wrong kit for your breaker type creates a safety hazard.
Installing an interlock kit requires drilling the panel cover and working near live electrical components. Most homeowners with basic DIY skills can handle it. However, you must turn off the main breaker before starting.
Electricians typically charge several hundred dollars to over a thousand for interlock installation. The job usually takes 1 to 2 hours. If you are not comfortable working inside a panel, hire a professional. The cost is worth the peace of mind.
Interlock kits are cheaper and simpler than transfer switches. A kit costs a fraction of what a transfer switch does. Transfer switches cost significantly more and require more complex wiring.
The interlock achieves the same safety goal by preventing simultaneous main and generator power. Transfer switches are required for some local codes, but interlock kits are NEC code compliant in most jurisdictions. Check with your local inspector before installing. Some areas require a licensed electrician to sign off on the work.
The XMK Eaton CH TAN kit holds the highest rating at 4.9 stars with 58 reviews. The GenSafety NCH200 and EXCELFU Eaton BR kits both hold 4.8 stars with larger review counts of 151 and 558 respectively.
The best interlock depends on your panel brand. For Eaton CH panels, the GenSafety NCH200 is the premium choice. For Eaton BR panels, the EXCELFU BR kit offers the best value. For Square D Homeline panels, the Natupal or S7 kits are top picks.
First, identify your panel brand by checking the label inside the panel door. Second, measure the center-to-center spacing between your main breaker and the generator breaker slot. Third, determine whether your main breaker moves horizontally or vertically. Match these three facts to the kit specifications before ordering.
Yes, generator interlocks are safe when installed correctly. They are mechanical devices that physically prevent the main breaker and generator breaker from being on simultaneously. This prevents dangerous backfeeding that could electrocute utility workers or damage your generator.
Most homeowners with basic DIY skills can install an interlock kit. The process involves drilling the panel cover and mounting the interlock plate. You must turn off the main breaker before working. If you are not comfortable working inside an electrical panel, hire a licensed electrician.
Installing a generator interlock kit is one of the most cost-effective safety upgrades you can make to your home. After comparing 14 different kits across every major panel brand, we are confident that the best generator interlock kits in 2026 deliver professional-grade safety at a fraction of the cost of transfer switches.
Our top pick is the GenSafety NCH200 for Eaton CH panels. It offers unmatched CNC-machined quality and Made in USA construction. For the best value, the EXCELFU Eaton BR kit dominates with 558 positive reviews. And if you are on a tight budget, the S7 Homeline kit gets the job done for the lowest cost.
Remember to measure your panel spacing, identify your brand, and verify your breaker throw direction before ordering. A few minutes of preparation saves you hours of returns and frustration. Stay safe this storm season.
