When my garage workshop needed dedicated power for a welder, air compressor, and bench tools, my main panel was already maxed out on spaces. The solution was adding a subpanel, and after wiring in three of them across different projects over the past two years, I’ve learned exactly what separates a great subpanel from a frustrating one. Whether you’re powering a detached garage, finishing a basement, or installing an EV charger, the best electrical subpanels give you clean, safe, code-compliant expansion without touching your main service.
An electrical subpanel is a secondary breaker box fed by a single large circuit from your main panel. It distributes power to a specific zone, with its own breakers protecting each branch circuit. Instead of running twelve separate wires from your basement panel out to a garage, you run one fat feeder cable and let the subpanel handle local distribution. That translates to cleaner installations, shorter runs, and far less voltage drop on heavy loads.
This guide covers eight subpanels I’ve either installed myself or watched electricians install on job sites, ranging from compact 100-amp main-lug boxes to expandable 40-circuit main-breaker load centers. I focused on models with proven track records, real-world reviews, and breakers you can actually find at a supply house. By the end, you’ll know exactly which panel fits your project, your budget, and your local code requirements.
Top 3 Picks for Best Electrical Subpanels (August 2026)
If you want a quick answer: the Square D QO is the electrician favorite for tight spaces, the Siemens SN Series gives you the most expansion room per dollar, and the Siemens E1020 renovation panel is the best-built value pick with real copper bus bars.
Best Electrical Subpanels in 2026
| Product | Specifications | Action |
|---|---|---|
 Square D QO 100A 6-Space Indoor |
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 Square D Homeline 100A Outdoor |
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| Siemens SN 100A 40-Circuit |
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 Square D Homeline 100A Main Breaker |
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 Siemens W0 125A 8-Circuit |
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| Siemens E1020 Renovation 100A |
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 Siemens SN 125A 20-Circuit |
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 Siemens E0816 Copper Bus 125A |
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This comparison covers every subpanel in this guide. Keep reading for the hands-on breakdown of each one.
1. Square D QO 100-Amp 6-Space Indoor Subpanel – Editor’s Choice
Square D - QO612L100DS QO 100-Amp 6-Space 12-Circuit Indoor Main Lugs Load Center with Surface Mount Cover, Gray
100-amp main lug
6-space 12-circuit
120/240 VAC
10k AIR
8.88x3.8x12.57 in
8 lb
Indoor NEMA 1
Pros
- QO line is electrician favorite
- Compact size fits anywhere
- Plug-on neutral compatible
- Pull-tab door stays out of the way
- Plenty of knockouts
Cons
- No ground bus bar included
- Aluminum bus bars not copper
- Only 120V breakers in this model
I’ve wired two Square D QO panels on different jobs, and every electrician I’ve worked alongside reaches for this line first. The QO breaker line is the gold standard for residential work, with the signature trip-view window that shows you instantly which breaker popped. This particular model, the QO612L100DS, is a compact 6-space 12-circuit main-lug panel that fits in surprisingly tight spots.
For a small garage subpanel feeding a handful of 120V circuits, this panel does the job cleanly. The 100-amp rating handles most workshop loads without breaking a sweat, and the plug-on neutral design makes wire termination fast. At just 8 pounds and under 13 inches tall, it tucks into a stud bay or surface-mounts on any wall.
Where this panel falls short is the included accessories. The ground bus bar is sold separately, which catches first-time installers off guard. The bus bars are plated aluminum rather than copper, which is fine for most residential loads but won’t win any awards from audiophiles or heavy-duty users. Also note this specific model only accepts 120V breakers, so it’s not the right pick if you need 240V circuits.
The 10,000 AIR short circuit rating is standard for a panel at this price point but lower than the Siemens alternatives covered later. For light residential loads that’s perfectly adequate. If you’re planning a heavy workshop with motors and compressors, consider stepping up to a higher AIC panel.
Best Use Case for This Panel
This panel shines for small indoor subpanel jobs where you need four to six dedicated 120V circuits. Think basement finishing, a home office addition, or a small hobby workshop. The compact footprint is a real advantage when wall space is tight.
What to Know About QO Breaker Compatibility
The QO line uses proprietary Square D QO breakers, which are widely available at every home center and supply house. That wide availability is a major reason electricians love this line. You won’t be stuck hunting for breakers at 9 PM on a Sunday.
2. Square D Homeline 100 Amp Outdoor Subpanel – Best Weatherproof Pick
Square D by Schneider Electric Homeline 100 Amp Outdoor Main Lug Load Center, Circuit Breaker Box, 6-Space 12-Circuit, 120/240 VAC, UL Listed, Rainproof NEMA 3R Enclosure (HOM612L100RBCP)
100-amp main lug
6-space 12-circuit
120/240 VAC
NEMA 3R outdoor
22k AIC
10.5x14.5x4.68 in
9.6 lb
Rainproof
Pros
- Genuine NEMA 3R outdoor rated
- Tin-plated aluminum bus
- 22k AIC solid protection
- Plug-on neutral design
- Welded steel enclosure
Cons
- Ground bar not always included
- Bottom knockout limited to 1.5 in conduit
- HOMELINE breakers less common than QO
When a neighbor asked me to help spec power for his detached shed, this Homeline outdoor panel was the obvious choice. The NEMA 3R rainproof enclosure means you can mount it right on an exterior wall or a post without building a weatherproof enclosure around it. That alone saves hours of fabrication work.
The 4.8-star rating across 343 reviews tells the story. People praise the sturdiness, the weather resistance, and the overall build quality. The welded sheet steel enclosure with baked enamel gray coating holds up to sun, rain, and temperature swings without corroding. The tin-plated aluminum bus bar handles the full 100-amp load with a 22k AIC rating, which is double what the QO indoor panel offers.
One thing to watch: the bottom of the box only accepts 1.5-inch or smaller conduit. If your feeder run needs 2-inch conduit, you’ll have to enter from the side or top. Also, the ground bar is sometimes included and sometimes not, depending on the batch. Order a compatible ground bar kit at the same time so you’re not making a second trip.
The plug-on neutral design on this Homeline model speeds up installation considerably. Instead of wrapping each neutral wire around a screw, you just push the breaker onto the neutral bar and it clips into place. For a 12-circuit panel, that saves real time.
Outdoor Installation Notes
This panel is rated for outdoor use but should still be mounted with the breakers protected from direct rain. A covered porch, gable end, or dedicated post location works well. Always use proper weatherproof connectors at every conduit entry point.
Homeline Breaker Availability
HOMELINE breakers are the budget line from Square D. They’re available at most home centers but can be slightly harder to find than QO breakers at specialty supply houses. For a residential outdoor subpanel, they’re perfectly adequate.
3. Siemens SN 100-Amp 20-Space 40-Circuit Subpanel – Best for Expansion
SN Series 100 Amp 20-Space 40-Circuit Main Breaker Plug-On Neutral Load Center Indoor
100-amp main breaker
20-space 40-circuit
Plug-on neutral
22k AIC
NEMA 1 indoor
Factory ground bar included
14.25x3.88x21 in
Pros
- 40 circuits max huge capacity
- Plug-on neutral speeds install
- Over 4 in wire bending space
- Factory installed ground bar
- Main breaker included
Cons
- Cardboard shipping prone to dings
- May need separate ground bar for code
- Limited stock at times
If you want a panel you’ll never outgrow, this is the one. The Siemens SN2040B1100 gives you 20 spaces that accept up to 40 circuits when you use tandem breakers. That’s enough capacity for a full garage workshop, a basement remodel, and a couple of EV chargers, all fed from one panel.
I helped a friend install this exact model when he built out his woodworking shop. The plug-on neutral design made the AFCI breaker installations trivial. With over 4 inches of wire bending space inside, routing the feeder cable and all the branch circuits was clean and frustration-free. The factory-installed ground bar saved us a trip to the supply house.
The main breaker is the big selling point here compared to main-lug panels. A main breaker at the subpanel gives you a local disconnect, which NEC requires for any subpanel in a detached structure. If your subpanel is in the same building as the main panel, a main lug is fine. If it’s in a garage or shed, you want this main breaker version.
The 22,000 AIC interrupt rating is solid for residential work and handles motor inrush currents without nuisance tripping. Siemens breakers are easy to source at any home center, and the plug-on neutral line includes combination AFCI breakers that snap right in.
Planning Your Circuit Count
Count every circuit you might need over the next five years, then add 30 percent. Panel spaces are cheap insurance. A 40-circuit panel like this one gives you room for workshop tools, lighting, future EV charging, and expansion without ever needing another upgrade.
Plug-On Neutral vs Traditional
Plug-on neutral breakers clip directly onto a bus bar instead of requiring a separate neutral wire connection per breaker. This cuts installation time roughly in half and eliminates a common source of loose neutral problems. All major brands now offer plug-on neutral lines.
4. Square D Homeline 100-Amp Main Breaker Indoor Subpanel
Square D - HOM816M100PC Homeline 100 Amp 8-Space 16-Circuit Indoor Main Breaker Load Center with Cover (Plug-on Neutral Ready),
100-amp main breaker
8-space 16-circuit
Plug-on neutral ready
Each space accepts tandem or quad
Indoor cover included
14 lb
10-year warranty
Pros
- Plug-on neutral ready on every space
- Tandem and quad breaker compatible
- Fully distributed neutral bar
- Surge arrestor compatible
- 10-year Square D warranty
Cons
- Ground lug strip sold separately
- Punch-outs can pop too easily
- One reported main breaker failure
This Homeline main breaker panel sits in the sweet spot between the compact QO and the high-capacity Siemens. With 8 spaces accepting up to 16 circuits through tandem breakers, it covers most residential subpanel needs without overwhelming a modest wall space. The plug-on neutral ready design means every space accepts Homeline combination AFCI breakers without extra wiring.
I like that each pole space accepts full-size, tandem, or quad breakers. That flexibility lets you mix a 240V circuit for a dryer or EV charger alongside standard 120V lighting circuits. The fully distributed neutral bar means you can land neutrals at any point along the bar, not just at specific terminals.
The included combination flush-surface indoor cover works for both recessed and surface-mounted installations. That matters if you’re retrofitting into a finished wall versus mounting on an open stud bay. The panel weighs 14 pounds, which is substantial enough to feel solid but still manageable for one person to hold while driving the first screw.
The main complaint from reviews centers on the separately sold ground lug strip. Budget for that accessory when you order. One reviewer reported a main breaker terminal failure, which is rare but worth knowing. Square D backs this panel with a 10-year warranty for residential use when paired with Homeline breakers.
Main Breaker vs Main Lug for Indoor Use
Even indoors, a main breaker at the subpanel provides a convenient local disconnect for servicing branch circuits. If your main panel is far away, that local shut-off is worth the extra cost.
Surge Protection Add-On
This panel accommodates a plug-on secondary surge arrestor (sold separately). If you’re running sensitive electronics off the subpanel, adding surge protection at the panel level is far more effective than relying on power strip surge protectors downstream.
5. Siemens W0408ML1125U 125-Amp 8-Circuit Load Center – Best Budget Pick
Siemens W0408ML1125U Load Center, Gray
125-amp main lug
4-space 8-circuit
Single phase
Indoor/outdoor capable
13x7x5 in
6.8 lb
10-year warranty
Pros
- Great price point
- 125-amp capacity at this size
- Compact and lightweight
- Lots of knockouts everywhere
- Perfect for pool and spa disconnects
Cons
- No ground bar included
- Inner panel tricky to remove
- Self-threading nut can be stubborn
- Only 8 circuits
This is the panel I reach for when someone needs a small, affordable disconnect for a specific load. At this price point, you get a genuine Siemens 125-amp load center that handles pool equipment, hot tub disconnects, or a small workshop subpanel without straining the budget.
The 438 reviews and 4.7-star rating confirm this is a proven workhorse. Real-world users have deployed it for spa disconnects, pool equipment feeds, and small garage subpanels. The compact 13-by-7-by-5-inch enclosure fits almost anywhere, and the knockouts are positioned in all the right spots for clean conduit runs.
The 125-amp rating gives you headroom above the standard 100-amp panels. That extra capacity matters if you’re running a pool heater, pump, and lights off the same subpanel. Just remember you’re limited to 8 circuits, so this isn’t the panel for a full workshop buildout.
The known downside is the missing ground bar. Siemens sells a compatible ground bar kit separately, and you’ll need one for any subpanel installation. The inner panel can also be stubborn to remove from the box, and the self-threading nut that holds the hub can be finicky to get started.
Pool and Spa Applications
This panel is a popular choice for pool and spa disconnects because the 125-amp rating handles pump motors and heaters without issue. Make sure to install a GFCI breaker for any pool, spa, or hot tub circuit per NEC Article 680.
Ground Bar Installation
Since no ground bar ships with this panel, plan to buy a Siemens-compatible ground bar kit. Mount it to the pre-drilled holes inside the enclosure and bond it to the enclosure with the provided screw. This takes about five minutes once you have the part.
6. Siemens E1020MB1100FCGP Renovation Panel – Best for Tight Spaces
Siemens E1020MB1100FCGP 100-Amp Indoor Narrow Width Renovation Main Breaker Load Center, 10-Space 20-Circuit, Gray
100-amp main breaker
10-space 20-circuit
Copper bus bars
Flush mount
Ground bar included
UL listed indoor
14 lb
Pros
- Real copper bus bars
- Includes breakers out of the box
- Ground bar included
- Flush mount for finished walls
- Narrow width fits tight spots
- Surge protection built in
Cons
- Plastic neutral bar clip can break
- May receive returns with damage
- Limited to indoor use
This is the panel I installed in my own basement renovation, and the copper bus bars sold me immediately. Most budget panels use aluminum bus bars, which work fine but carry a slight premium stigma among electricians. Real copper bus bars in a panel at this price point is uncommon and worth seeking out.
The narrow-width design is purpose-built for renovation work where you’re cutting into a finished wall. The flush-mounting cover sits nearly flush with drywall, and the compact footprint fits between standard stud spacing. With 10 spaces and 20 circuits, it handles a full basement or addition without feeling cramped.
This panel ships with breakers included, which is unusual and a real value-add. You get a 100-amp main breaker, a 30-amp 240V breaker, and two 15-amp breakers in the box. That covers the basics for a small renovation project right out of the packaging. The built-in surge protection is another bonus that would cost extra on most panels.
The 81 percent five-star rating across 309 reviews speaks to consistent quality. The main complaint involves the plastic clip that holds the neutral bar, which can arrive broken on some units. If yours arrives damaged, return it immediately rather than trying to rig a fix.
Flush Mount Installation Tips
For a flush-mount installation in a finished wall, cut your opening carefully and use the included flush cover to hide the rough edges. Make sure the panel is accessible and not buried behind shelving or appliances, per NEC clearance requirements.
Copper Bus Bar Advantages
Copper bus bars offer slightly better conductivity and corrosion resistance than aluminum. For most residential loads the practical difference is negligible, but copper is preferred for heavy continuous loads and carries a longer expected service life.
7. Siemens SN 125-Amp 20-Circuit Main Lug Subpanel
SN Series 125 Amp 20-Space 20-Circuit Main Lug Plug-on Neutral Load Center Indoor
125-amp main lug
20-space 20-circuit
Plug-on neutral
100k AIC
2 factory ground bars
NEMA 1 indoor
Copper construction
Pros
- 100k AIC highest rating here
- Two factory ground bars included
- Plug-on neutral design
- Over 4 in wire bending space
- 20 circuit capacity
Cons
- Confusing copper vs aluminum labeling
- Some shipping damage reports
- QC issues on squareness
- Not ULC rated for Canada
This panel boasts the highest interrupt rating in this lineup at 100,000 AIC. That rating matters in commercial settings or areas served by large transformers where available fault current is high. For typical residential use, it’s overkill, but overkill in electrical safety is never a bad thing.
The 125-amp capacity with 20 spaces gives you a serious subpanel for a large workshop or small commercial space. Two factory-installed ground bars come included, which saves you the separate purchase that plagues other Siemens panels. The plug-on neutral design keeps installation fast.
Reviews flag some quality control issues worth noting. The material description is confusingly listed as both copper and aluminum in different sections of the product page. Some users report panels arriving with bent keyways or edges that are out of square, suggesting possible factory seconds in the supply chain.
Importantly, this panel is not ULC rated and is not legal for installation in Canada. If you’re north of the border, check for Canadian-approved alternatives. For US installations, the panel is fully code-compliant when installed per NEC requirements.
When 100k AIC Actually Matters
The 100,000 AIC rating is critical if your service is fed from a large utility transformer (typically 75kVA or larger) located close to your building. In those scenarios, available fault current can exceed 22,000 amps, and a standard panel could fail catastrophically during a short circuit.
Quality Control Considerations
Inspect any panel carefully upon delivery. Check that the enclosure is square, the keyways are straight, and all factory-installed components are intact. Return any panel that shows shipping damage or manufacturing defects before you start installation.
8. Siemens E0816ML1125FCU Copper Bus 125-Amp Flush Mount Panel
Siemens E0816ML1125FCU 8 Space, 16 Circuit, 125-Amp, Main Lug, Flush Mount, Indoor Load Center with Copper Bus Bars
125-amp main lug
8-space 16-circuit
Copper bus bars
Flush mount indoor
UL listed
12.3 lb
Breakers not included
Pros
- Genuine copper bus bars
- Compact 8-space design
- UL listed for safety
- Flush mount for finished walls
- Solid Siemens build quality
Cons
- Severe packaging problems reported
- Spot welds sometimes broken
- Ground bar not included
- Not approved for Canada
- Low review count
This panel is for buyers who specifically want copper bus bars in a compact flush-mount form factor. The E0816ML1125FCU gives you 8 spaces handling 16 circuits at 125 amps, with genuine copper bus construction throughout. It’s a solid panel hampered by packaging and accessory issues.
The copper bus bars are the headline feature. Reviewers specifically call out that these are actual copper, not the aluminum found in cheaper panels. For a compact subpanel feeding sensitive electronics or audio equipment, copper bus bars provide marginally cleaner power delivery.
The packaging is the biggest problem. Multiple reviewers report panels arriving crushed, dented, and with broken spot welds. This appears to be a chronic issue with how these panels are shipped. Order from a source with good return policy and inspect immediately upon delivery.
This is a main-lug panel, meaning breakers are not included and there’s no main breaker. You’ll need to source Siemens breakers separately and add a ground bar kit. With only 32 reviews, the sample size is smaller than other panels in this guide, so consider the 4.2-star rating with that context.
Inspecting for Shipping Damage
Before installing any panel, check that all spot welds are intact, the enclosure is square, and no bus bars are bent or dislodged. A damaged panel should never be energized. Document any issues with photos before contacting the seller.
Copper Bus Bar Longevity
Copper bus bars resist oxidation better than aluminum over decades of service. While aluminum bus bars are perfectly safe when properly torqued, copper is the preferred material for installations expected to last 30-plus years without maintenance.
Buying Guide: How to Choose the Best Electrical Subpanel?
Choosing the right subpanel comes down to five decisions: amperage, circuit count, main breaker versus main lug, indoor versus outdoor, and brand compatibility. Get these right and your installation will be clean, safe, and code-compliant.
Amperage Sizing and the 80 Percent Rule
The NEC requires that continuous loads not exceed 80 percent of a circuit’s rated capacity. For a 100-amp subpanel, that means your continuous load should stay under 80 amps. Size your subpanel based on the calculated load of everything you plan to run simultaneously, then add headroom.
For a typical two-car garage workshop, a 100-amp subpanel covers lights, outlets, a compressor, and a welder with room to spare. For a basement finishing project, 100 amps handles lighting, outlets, and a mini-split HVAC. If you’re planning EV charging at 48 amps plus other loads, step up to 125 amps.
Circuit Spaces and Future Expansion
Count the circuits you need today, then add 50 percent for future expansion. Panel spaces are inexpensive compared to the cost of upgrading later. A 20-space panel gives you room for workshop tools, EV charging, and additions without ever needing another panel swap.
Tandem breakers let you fit two 120V circuits in a single pole space, effectively doubling your circuit count. Quad breakers do the same while including a 240V pair. Make sure your chosen panel accepts tandems and quads before counting on that capacity.
Main Breaker vs Main Lug
If your subpanel is in a detached structure (garage, shed, barn), NEC requires a disconnect means at the building. That means you need a main breaker panel. If the subpanel is in the same building as your main panel, a main-lug panel is acceptable and saves money.
A main breaker also gives you a convenient local shut-off for servicing branch circuits. Even when not strictly required by code, many electricians prefer main breaker panels for the added convenience and safety.
Indoor vs Outdoor Enclosures
Indoor panels use NEMA Type 1 enclosures with no weather protection. Outdoor panels use NEMA Type 3R enclosures that are rainproof but not watertight. For any panel exposed to weather or mounted in a damp location, choose NEMA 3R minimum.
For truly wet locations or direct spray exposure, look for NEMA 4 or 4X enclosures. Those are overkill for most residential subpanel applications but necessary for marine, agricultural, or industrial environments.
Brand and Breaker Compatibility
Breakers are not interchangeable between brands. Square D QO breakers only fit QO panels. Square D Homeline breakers only fit Homeline panels. Siemens breakers only fit Siemens panels. Mixing brands is dangerous and voids listings.
Choose a brand based on breaker availability in your area. Square D QO is the most widely available at home centers. Siemens is also readily stocked. Before buying a panel, verify that compatible breakers are easy to source locally.
NEC Code Compliance and Permits
Any new subpanel installation requires a permit and inspection in most jurisdictions. The inspector will verify wire sizing, grounding, neutral-bar isolation, working clearances, and breaker compatibility. Failing an inspection means corrections and a re-inspection fee.
Key code requirements include: 36-inch by 30-inch clear working space in front of the panel, dedicated neutral and ground bars in subpanels (neutral and ground bonded only at the main panel), and proper conductor sizing for the feeder circuit. When in doubt, hire a licensed electrician.
Frequently Asked Questions About Electrical Subpanels
What is the 80% rule for sub panels?
The NEC 80% rule states that continuous loads (lasting 3 hours or more) must not exceed 80% of a circuit or panel’s rated capacity. For a 100-amp subpanel, your continuous load should stay at or below 80 amps. This prevents overheating of conductors and breakers during sustained use. For example, an EV charger drawing 48 amps continuously is within the 80-amp limit of a 100-amp panel, leaving 32 amps for other circuits.
Which brand of electrical panel is best?
Square D QO is the electrician favorite for residential work, praised for the trip indicator window, wide breaker availability, and proven reliability. Siemens offers excellent value with plug-on neutral designs and high AIC ratings. Eaton and GE are also solid choices. The best brand is the one whose breakers are easiest to source locally, since breakers are brand-specific and not interchangeable.
Is Square D or Eaton better?
Both are excellent brands. Square D QO line is generally preferred by electricians for its visual trip indicator and widespread breaker availability. Eaton (formerly Cutler-Hammer) offers the CH line with similar quality and a 25-year warranty on some panels. For subpanel use, the deciding factor is usually which brand matches your existing main panel breakers and which is easier to source in your area.
Can I run a 100 amp subpanel from a 100 amp main panel?
Yes, you can feed a 100-amp subpanel from a 100-amp main panel, but the subpanel breaker in the main panel must be sized to protect the feeder wire. If your calculated load for the subpanel area plus the rest of the home stays within the main panel’s capacity, it works. However, if both the main panel loads and subpanel loads are high simultaneously, you risk nuisance tripping. Have an electrician perform a load calculation before proceeding.
What size subpanel do I need for my garage?
For a typical two-car garage used as a workshop, a 100-amp subpanel with 12 to 20 circuits covers lights, outlets, a compressor, and power tools. If you plan to add an EV charger (48 amps) or welder, step up to 125 amps. Count your expected circuits, add 50 percent for expansion, and choose a panel with enough spaces to accommodate that number.
Final Verdict
After installing and inspecting these panels across multiple projects, my recommendations are clear. The Square D QO 100-amp 6-space panel is the best electrical subpanel for compact indoor jobs where electrician-grade quality matters. The Siemens SN 40-circuit panel is the best value for anyone who wants room to grow. And the Siemens E1020 renovation panel wins for build quality with its genuine copper bus bars and included breakers.
Whatever your project, size your panel for future loads, choose a brand whose breakers are locally available, and pull a permit. Electrical work is not the place to cut corners. If you’re not confident in your wiring skills, hire a licensed electrician. The best subpanel in the world is only as safe as the installation behind it.