Price a 2026 garage, ADU, basement, or detached-structure subpanel install by amperage, location, and feeder run length — then line up 3 licensed electrician quotes.
Subpanel Size
Location
Install Details
Region
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Frequently Asked Questions
Q
How much does it cost to install a subpanel in 2026?
$400-$900 for a 50-60A subpanel in an attached garage, $700-$2,200 for a 100A subpanel inside an attached structure, $2,000-$4,500 for a 100A subpanel in a detached garage with a trenched feeder, and $1,800-$4,500 for a 200A ADU or addition subpanel. National median runs about $1,205 (Angi 2026). Total includes the subpanel enclosure, the feeder breaker added at the main panel, 4-wire feeder cable and conduit, 4-8 hours of licensed electrician labor, and the electrical permit.
How much extra does a detached garage subpanel cost vs an attached one?
Detached subpanels run $800-$2,500 more than attached at the same amperage. The premium covers trenching the feeder run ($6-$13.50 per linear foot, 18-inch minimum depth in conduit or 24-inch direct burial), conduit and a 4-wire feeder cable per NEC 250.32, a separate ground rod at the detached structure ($200-$500), and typically a separate disconnect switch at the building. A 100A detached install with a 50-foot trenched feeder lands at $2,500-$3,800 in most US markets versus $1,200-$1,800 for the same amperage on an interior wall.
Trenching: $6-$13.50 per linear foot
4-wire feeder cable required since NEC 2008 (NEC 250.32)
Separate ground rod on detached structure: $200-$500
Separate disconnect at detached building: $80-$250
Cold-climate frost-line trench (36-48 inch depth): adds 10-15%
Subpanel Location
100A Installed Cost
Notes
Attached interior wall (next to main panel)
$700-$1,400
Cleanest install, 2-3 hr labor
Attached garage (shared wall)
$900-$1,800
Through-wall pull, 4-5 hr labor
Detached garage (50 ft trenched)
$2,000-$3,800
Trench + ground rod + 4-wire feeder
Detached structure (100 ft trenched)
$2,800-$4,500
Long run, deeper trench, more conduit
Q
What size subpanel do I need for a garage, ADU, or addition?
Match amperage to load: 60A handles a 2-car garage with lights, outlets, and a door opener ($400-$900). 100A handles a workshop with a table saw, dust collector, or a small ADU ($700-$2,200 attached, $2,000-$4,500 detached). 125A handles a large workshop or a small addition ($900-$2,800). 200A is required for a full ADU with an EV charger, electric range, electric water heater, or mini-split system ($1,800-$4,500). Under-sizing trips the feeder breaker on overload; over-sizing wastes $200-$800 in unused capacity.
60A: 2-car garage with lights + outlets ($400-$900)
100A: workshop, basement remodel, small ADU ($700-$2,200)
125A: large workshop, small addition ($900-$2,800)
200A: full ADU with EV charger + range ($1,800-$4,500)
Subpanel amperage must not exceed main panel headroom
Amperage
Use Case
Typical Circuit Count
50-60A
Small garage, shed, hobby room
4-8
100A
Workshop, basement, small ADU
12-20
125A
Large workshop, addition
16-24
200A
Full ADU, EV + range + mini-split
30-40
Q
Do I need a permit and inspection for a subpanel install?
Yes — virtually every US jurisdiction requires an electrical permit ($50-$300) and a post-install inspection for any subpanel tied into the main service panel. The inspector specifically verifies that the bonding screw is removed at the subpanel, that grounds and neutrals are isolated on separate bus bars, that the feeder cable is 4-wire per NEC 250.32, and that the feeder breaker amperage matches the cable rating. Unpermitted subpanels frequently surface during home-sale disclosure or insurance claim denials, triggering retroactive permitting at 2-3x the original fee.
Electrical permit: $50-$300 most US jurisdictions
NEC 250.32 governs subpanels in separate structures
Inspector verifies isolated grounds + neutrals (no bonding screw)
4-wire feeder mandatory since 2008 for new installs
Unpermitted installs void home insurance
Q
Can I install a subpanel myself to save money?
Most US states require a licensed electrician for any work on the main service panel — including the feeder breaker that powers the subpanel. Some states allow a homeowner permit on the subpanel itself if the homeowner occupies the structure, saving $300-$700 in labor on a $1,000-$2,000 install. The most common DIY failure is leaving the neutral-to-ground bonding screw installed at the subpanel, which creates a parallel current path through the metal enclosure and triggers an automatic inspection failure. Even on DIY-permitted installs, the post-install inspection at $75-$200 is non-negotiable.
Service-panel-side work: licensed electrician required in most states
DIY subpanel-side install saves $300-$700 if permitted
Most common failure: bonding screw left installed
Post-install inspection required regardless of who installs
DIY voids home insurance in many policies
Q
How do I avoid overpaying on a subpanel install?
Get 3 written quotes from licensed electricians and verify each bid breaks out subpanel hardware, feeder breaker, feeder cable footage, conduit, labor hours, permit, and (for detached structures) trenching plus ground rod. Confirm the feeder breaker amperage matches the feeder cable rating and the subpanel busbar rating. Cap deposits at 25-33% of the contract; on a $1,500 install that is $375-$500 maximum. Verify the electrician's license and general liability Certificate of Insurance before any work begins. Bids 25%+ below the pack often skip the permit or use 3-wire feeder.
Total installed = subpanel enclosure ($80-$600 by amperage) + feeder breaker added at the main panel ($30-$120) + 4-wire feeder cable per NEC 250.32 ($1-$5/ft installed depending on amperage and copper vs aluminum) + EMT or PVC conduit ($2-$6/ft installed) + 4-8 hours of licensed electrician labor at $80-$150/hr ($320-$1,200) + electrical permit and inspection ($50-$300). Detached structures add trenching ($6-$13.50/ft, 18-24 inch min depth), a separate ground rod ($200-$500), and typically a disconnect at the detached building ($80-$250). West Coast and Northeast coastal labor adds 20-30%; cold-climate frost-line trench depth adds 10-15% on detached runs.
Where:
Subpanel= Enclosure + busbars + main lugs; $80-$600 by amperage and brand (Square D, Eaton, Siemens)
Feeder Breaker= Double-pole breaker added at the main panel feeding the subpanel; sized to feeder cable and subpanel busbar rating
Feeder Cable= 4-wire (2 hots + neutral + ground) sized to amperage; #6 Cu for 60A, #3 Cu / #2 Al for 100A, #2/0 Cu / 4/0 Al for 200A
Conduit= EMT for indoor pulls, Schedule 40 PVC for direct burial; sized to fill ratio
Labor= Licensed electrician 4-8 hrs depending on amperage, location, and feeder run complexity
Permit= Electrical permit + post-install inspection; NEC 250.32 compliance verified
Subpanel Install Cost in 2026: Garage, Detached, ADU, and Addition Subpanel Pricing
1
Subpanel Install Cost in 2026: The Short Answer
A residential subpanel installed in 2026 runs $400-$900 for a 50-60A subpanel inside an attached garage, $700-$2,200 for a 100A subpanel on an interior wall or attached garage, $2,000-$4,500 for a 100A subpanel in a detached garage with a trenched feeder, and $1,800-$4,500 for a 200A ADU or addition subpanel. The national median across all configurations is $1,205, with the typical 80% range running $495-$2,250 (Angi 2026). Each installed figure bundles the subpanel enclosure, the new feeder breaker that gets added at the main panel, 4-wire feeder cable and conduit per NEC 250.32, 4-8 hours of licensed electrician labor at $80-$150 per hour, and the electrical permit and post-install inspection.
The single biggest dollar lever is location: attached vs detached. An attached subpanel is a relatively clean install — the electrician routes the feeder through an interior wall or shared garage wall, runs 25-50 feet of cable in EMT conduit, and lands the install in 4-5 billable hours. A detached subpanel adds $800-$2,500 over the same amperage attached install: trenching at $6-$13.50 per linear foot, 18-inch minimum trench depth in conduit (24-inch direct burial), a separate ground rod at the detached building per NEC 250.32 ($200-$500), and typically a separate disconnect at the structure ($80-$250). The electrical panel upgrade cost calculator prices the upstream main-panel work if your existing service can't handle the new feeder load.
Amperage is the secondary lever. A 50-60A subpanel ($400-$900 installed attached) handles a 2-car garage with lights, outlets, and a door opener. A 100A subpanel ($700-$2,200 attached, $2,000-$4,500 detached) handles a workshop with a table saw and dust collector or a small ADU. A 200A subpanel ($1,800-$4,500) is required for a full ADU with an EV charger, electric range, electric water heater, and mini-split — the loads add up fast. Hardware cost scales roughly linearly with amperage: $80-$200 for 50-60A, $120-$350 for 100A, $250-$600 for 200A. The feeder cable also scales with amperage, jumping from $1-$2 per foot installed for #6 Cu (60A) to $4-$5 per foot for #2/0 Cu or 4/0 Al (200A).
Subpanel installed cost by amperage and location, 2026. Source: HomeGuide, Angi, Homewyse.
Configuration
Hardware Cost
Installed Cost 2026
Best For
50-60A attached subpanel
$80-$200
$400-$900
Small garage, shed, workshop
100A attached subpanel
$120-$350
$700-$2,200
Workshop, basement remodel, small ADU
100A detached subpanel (trenched)
$200-$500
$2,000-$4,500
Detached garage, separate workshop
125A subpanel (attached)
$180-$420
$900-$2,800
Large workshop, addition
200A ADU / addition subpanel
$250-$600
$1,800-$4,500
Full ADU with EV charger + range
A 100A subpanel installed in an attached garage with a 35-foot feeder run — the single most common US residential subpanel configuration — runs $1,200-$1,700 turnkey in 2026. That is the number to benchmark mid-range quotes against.
2
Attached vs Detached Subpanel: The $800-$2,500 Delta
The largest single factor in subpanel pricing is whether the new panel sits inside the same structure as the main service panel, or in a detached building (garage, workshop, ADU, barn). At the same amperage, a detached subpanel runs $800-$2,500 more than an attached install. The premium covers four specific work items the attached install doesn't need: trenching the feeder run between the buildings, a 4-wire feeder cable per NEC 250.32 (post-2008 requirement), a separate ground rod at the detached structure, and typically a disconnect switch where the feeder enters the building. Each item is small individually; the bundle is what swings the bill.
Trenching is the largest single line item on a detached install. National rates run $6-$13.50 per linear foot for a hand-dug or mini-excavator-cut trench at the 18-inch minimum depth required for PVC conduit (24-inch for direct burial). A typical 50-foot run between an attached garage and a detached workshop adds $300-$675 in trench cost alone, before the cable, conduit, or labor lands in the trench. Cold-climate states (Upper Midwest, New England, Mountain West) require frost-line depth of 36-48 inches on direct-burial runs, pushing trench cost 10-15% higher than the national baseline. Long runs (100-150 feet) become 5-8 hour excavator jobs that add $700-$1,800 to the total.
The 4-wire feeder requirement is the second detached-specific cost. Pre-2008 NEC allowed a 3-wire feeder (2 hots + combined neutral/ground) on detached buildings, but NEC 250.32 (effective 2008) mandates a 4-wire feeder (2 hots + isolated neutral + isolated ground) plus a separate ground rod at the detached building. The 4-wire requirement adds about 30% to the cable cost and forces the installer to keep grounds and neutrals isolated at the subpanel busbars, which is the same isolation rule that applies to attached subpanels. The separate ground rod at the detached structure adds $200-$500 (rod, clamps, bonding wire, 2 hours of labor) and is non-negotiable for inspection sign-off.
100A subpanel installed cost by location and feeder distance, 2026.
Subpanel Location
100A Installed Cost
Notes
Attached interior wall (next to main panel)
$700-$1,400
Cleanest install, 2-3 hr labor
Attached garage (shared wall)
$900-$1,800
Through-wall pull, 4-5 hr labor
Detached garage (50 ft trenched)
$2,000-$3,800
Trench + ground rod + 4-wire feeder
Detached structure (100 ft trenched)
$2,800-$4,500
Long run, deeper trench, more conduit
Detached structure (150 ft trenched, cold climate)
$3,500-$5,500
Frost-line depth + long run + ground rod
Trenching: $6-$13.50 per linear foot (hand-dug to mini-excavator)
4-wire feeder cable per NEC 250.32 (2008+): +30% over 3-wire
Separate ground rod at detached structure: $200-$500
Disconnect at detached building entry: $80-$250
Long feeder run (100-150 ft): +$700-$1,800
3
Sizing the Subpanel: 60A Garage vs 100A Workshop vs 200A ADU
Picking the right amperage is the second most important decision after location, and it's where the most expensive sizing mistake happens. The right approach is to add up the loads the subpanel will feed (in amps at 240V, then double-counted via the 80% continuous-load rule for items running more than 3 hours), then size the subpanel one step above the calculated demand. A 2-car garage with lights, four 20A outlets, a door opener, and an air compressor draws roughly 35-45 amps at peak; a 60A subpanel handles that with headroom and lands at $400-$900 installed. A workshop with a 50A table saw plus a 30A dust collector plus two 20A outlets totals 60-80A peak; a 100A subpanel is the right call at $700-$2,200 attached.
ADU and full-addition subpanels are where 200A becomes the standard. A modern ADU with an EV charger (40-50A continuous), an electric range (40A), an electric water heater (30A), a mini-split heat pump (20-30A), and the standard lighting and outlet circuits totals 130-170A at peak, putting a 200A subpanel right in the sweet spot at $1,800-$4,500 installed. Under-sizing to 100A on an EV-charger ADU is the most common sizing mistake — the breaker trips the first time the EV charges while the range and water heater are running. Pair the EV charger install cost calculator with this sizing decision because the EV charger is usually the single largest continuous load on the subpanel.
The amperage decision also affects the feeder cable and the feeder breaker added at the main panel. A 60A subpanel uses #6 Cu or #4 Al feeder ($1-$2 per foot installed) and a 60A double-pole feeder breaker (~$30). A 100A subpanel uses #3 Cu or #2 Al feeder ($2-$3 per foot installed) and a 100A breaker (~$50). A 200A subpanel uses #2/0 Cu or 4/0 Al feeder ($4-$5 per foot installed) and a 200A breaker (~$100-$150). Hardware scales roughly linearly with amperage; labor stays roughly flat (4-6 hours regardless of amperage on attached installs). Critically, the feeder breaker amperage at the main panel must match the feeder cable rating AND must not exceed the subpanel busbar rating — over-sizing the feeder breaker on undersized cable creates a fire-risk overcurrent condition that auto-fails inspection.
A 200A ADU subpanel with an EV charger pairs cleanly with a solar battery backup cost calculator sizing — the same 200A panel can be the integration point for a 10-15 kWh battery system on the ADU side, avoiding a second main-panel modification.
100A subpanel: workshop, basement remodel, small ADU — $700-$2,200 attached
125A subpanel: large workshop, small addition — $900-$2,800 attached
200A subpanel: full ADU with EV + range + water heater + mini-split — $1,800-$4,500
Subpanel amperage cannot exceed the main panel's available headroom
Under-sizing trips the feeder breaker; over-sizing wastes $200-$800
Feeder breaker at main panel must match feeder cable + busbar ratings
4
Subpanel Install Cost Breakdown by Component
A typical $1,500 100A attached subpanel install decomposes into five buckets: subpanel enclosure plus the new feeder breaker added at the main panel at 25% of total (~$375), feeder cable and EMT conduit (35 feet) at 18% (~$270), licensed electrician labor (5 hours at $120 per hour) at 40% (~$600), electrical permit and inspection at 10% (~$150), and miscellaneous hardware (lugs, anti-oxidation paste, knockouts, screws, anti-short bushings) at 7% (~$105). Across this typical configuration, labor is the largest single line and tracks directly with the complexity of the feeder routing — a clean wall-cavity pull is 3-4 hours, a basement-to-garage pull through joist bays is 5-6 hours, a detached pull with trenching is 7-8 hours.
The donut visualizes the typical 100A attached install split. When evaluating multiple quotes, recast each bid into these five buckets and outliers become obvious. A quote where the hardware line is suspiciously low (under 20% of total) often indicates a generic or off-brand subpanel from a non-major manufacturer — acceptable on smaller installs, but verify UL listing and breaker compatibility (the subpanel must accept the breaker brand the electrician plans to install). A quote where the labor line is below 30% of total usually means the electrician is planning a 2-3 hour install that skips proper conduit fastening, knockout sealing, breaker labeling, or the post-install meg-ohm test on the feeder.
On detached installs, the breakdown shifts notably. Trenching becomes a sixth bucket worth 10-15% of total (~$300-$700 on a typical $2,800 detached install), the ground rod plus bonding hardware becomes a seventh bucket worth 7-10% (~$200-$280), and the feeder cable percentage climbs to 22-25% because of the longer run and the 4-wire premium. Labor stays at 35-40% because the longer run and the trench landing absorb the additional electrician hours. Permit cost is roughly the same dollar amount but a smaller percentage (5-7%) because the total bill is larger. Always insist that detached quotes itemize trenching as a separate line — bundled trench-plus-cable line items hide whether the contractor is hiring a sub for the dig or doing it in-house.
One budget line item that's often missing on lowball quotes is the load calculation at the main panel. A proper Manual J-style residential load calc verifies that the existing main service amperage (100A, 150A, 200A) can actually handle the new subpanel feeder plus the existing house loads. Skipping the load calc on a 100A main service that's already at 80% of nameplate capacity creates a feeder breaker that trips every time the AC compressor cycles on at the same time as the dryer or oven. Insist that a written load calc appear on the quote, and if the existing main service is undersized, price the upstream upgrade with the electrical panel upgrade cost calculator before committing to the subpanel work.
Insist that the load calc at the main panel appears in writing on the quote. Skipping it on a 100A main already at 80% capacity creates a feeder breaker that trips whenever the AC and dryer run together — and the fix is the upstream service upgrade, which costs more than the subpanel itself.
5
Common Subpanel Install Mistakes That Trigger Re-Inspection
Subpanel installs have a specific set of failure modes that show up on the inspector's punchlist with depressing regularity. The most common — and the most dangerous — is leaving the neutral-to-ground bonding screw or strap installed at the subpanel. In a main service panel, the neutral and ground bus bars are bonded together (that's where the grounding electrode conductor lands and where the system grounding reference is established). In every subpanel downstream of the main panel, the bonding must be removed so that grounds and neutrals are isolated on separate bus bars. Leaving the bonding screw installed creates a parallel current path through the metal subpanel enclosure and the equipment grounding conductor, which can energize metal appliance casings during a fault and create a fatal shock hazard.
The second most common mistake — common in pre-2008 retrofits and DIY work — is using a 3-wire feeder (2 hots + combined neutral/ground) on a new subpanel install. NEC 250.32 has required a 4-wire feeder (2 hots + isolated neutral + isolated ground) on every subpanel since the 2008 code cycle, with a separate ground rod at detached structures. A 3-wire feeder fails inspection on the spot and forces a re-pull of the feeder cable — typically a $300-$1,200 cost depending on the run length and whether the existing conduit can accommodate the 4th conductor. Always verify the feeder cable in the contractor's bid is 4-wire and that the install plan keeps grounds and neutrals isolated at the subpanel busbars.
Other recurring failures: missing the separate ground rod at a detached structure (auto-fail per NEC 250.32 — the rod is non-negotiable, $200-$500 to add post-install if forgotten); trench depth too shallow (under 18 inches in conduit or 24 inches direct burial — the inspector will measure); feeder breaker oversized at the main panel (e.g., a 100A breaker on a #6 Cu cable rated for 65A — auto-fail, the breaker must protect the cable not the load); subpanel busbar amperage rating exceeded by the feeder breaker (a 200A breaker feeding a 100A-rated subpanel is the most common variant); missing anti-oxidation paste on aluminum lugs (slow-burn failure that surfaces 6-18 months later as a loose connection and arcing). Each of these is fixable, but each costs $100-$1,500 in callback labor plus re-inspection fees.
Bonding screw left installed at subpanel (parallel current path, fail inspection, fatal shock risk)
3-wire feeder used post-2008 (NEC 250.32 requires 4-wire — auto-fail)
Missing separate ground rod on detached structure (auto-fail)
Trench too shallow — under 18 in conduit, under 24 in direct burial
Feeder breaker oversized vs feeder cable rating (overheats cable before tripping)
Missing anti-oxidation paste on aluminum lugs (slow-burn failure)
Knockouts left open without bushings (rodent + moisture intrusion)
6
Permits, NEC 250.32, and How to Avoid Overpaying
Subpanel installation is a permit-required job in virtually every US jurisdiction, with permit fees running $50-$300 depending on the city or county. The permit covers the electrical inspector's site visit (sometimes two visits — rough-in for the feeder run and final for the energized panel), and it's the single line item most commonly omitted from lowball quotes. A $1,200 quote that excludes the permit looks competitive against a $1,400 quote that includes it, but the $200 permit fee is buying two things the cheaper quote isn't: legal compliance under NEC 250.32, and an independent inspector verifying that the bonding screw is removed, the feeder is 4-wire, the ground rod is installed (on detached), the feeder breaker matches the cable rating, and the trench is at code depth.
Skipping the permit creates a discoverable defect at home-sale time. Buyers' home inspectors routinely flag unpermitted electrical work, and the fix is retroactive permitting at the city/county — typically 2-3x the original permit fee plus a re-inspection that often turns up additional remediation work. A $200 saved at install becomes $600-$1,800 (plus 2-4 weeks of delay) at home sale. Unpermitted electrical work also voids most homeowner insurance policies on any related claim — if the unpermitted subpanel feeds an EV charger that catches fire, the insurer can deny the claim and recover any payout already disbursed. Always pay the permit at install time.
Standard buyer protections apply with a few subpanel-specific twists. Cap deposits at 25-33% of the contract — on a $1,500 attached install that's $375-$500 maximum, on a $3,500 detached install that's $875-$1,150 maximum. Bids 25%+ below the pack on the same configuration are usually skipping one of three things: the permit (creates retroactive permitting problem), the 4-wire feeder (forces re-pull at inspection), or the load calc at the main panel (creates a tripping feeder breaker after install). Verify the electrician's license and general liability Certificate of Insurance before signing — license verification is free at the state board website and takes under five minutes.
For homeowners pairing the subpanel with broader electrical upgrades, two adjacent calculators are worth running. The standby generator install cost calculator prices a generator that can backfeed the subpanel during outages — useful for ADU, basement remodel, and detached workshop subpanels where the existing main-panel ATS coverage doesn't extend. The solar battery backup cost calculator prices a battery alternative that integrates cleanly with a 100-200A subpanel as the load-side connection point. Bundling the subpanel and the backup-power install on a single permit can save $100-$300 in filing fees and one electrician trip charge.
Maximum deposit: 25-33% of contract; 50%+ upfront is a scam signal
Cheapest bid 25%+ below pack — usually skips permit, 4-wire feeder, or load calc
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.
