Is a 60A subpanel enough for a detached garage?

It can be enough for a modest, documented load plan, but only when the adopted-code calculation, simultaneous loads, voltage-drop design, existing service capacity, and future equipment all fit. Breaker ratings should not simply be added to make this decision.

Can a 100A panel be supplied by a 60A feeder?

A panelboard with a 100A bus rating can sometimes be protected by a smaller feeder overcurrent device, provided the equipment is listed and configured for that use. The electrician and AHJ must verify the complete feeder, disconnect, labeling, and panel arrangement.

What size subpanel for a detached garage? 60A vs. 100A

For most detached garages, the real choice is not “60A or 100A by default.” Choose 60A only when a licensed electrician’s load calculation shows that today’s loads, realistic simultaneous use, and planned additions fit. Consider 100A when an EV charger, welder, compressor, electric heat, or mini-split could overlap—and only if the house service and installation design support it.

If the garage needs only one limited circuit, a subpanel may be unnecessary. Start with the detached-garage feeder versus branch-circuit guide before selecting capacity.

Know which “subpanel size” you mean

Four different numbers often get mixed together:

Panelboard rating: the maximum rating of the panel’s bus and equipment, subject to its listing.
Feeder rating: the overcurrent protection and conductors supplying the garage.
Calculated load: the code calculation for what the feeder is expected to serve.
Breaker spaces: how many branch circuits the panel can physically accept.

A 100A-rated panel does not automatically receive a 100A feeder, and installing it does not add 100 amps to the home’s service capacity. A larger panelboard may provide useful spaces while a smaller feeder protects it, but the equipment listing, main-breaker or disconnect arrangement, labels, and AHJ approval must all support that design.

60A vs. 100A detached-garage decision matrix

Use this matrix to frame a quote, not to approve your own feeder.

Decision factor	60A is a candidate when…	100A is a candidate when…
Present loads	Lighting, receptacles, and limited equipment produce a compliant calculated load with margin	Several substantial 120/240V loads are planned
Simultaneous use	Large tools or equipment will not realistically operate together	EV charging, welding, compression, dust collection, or HVAC may overlap
Future plan	No credible major load is expected during the garage’s service life	A second EV, larger welder, lift, heater, mini-split, or shop machinery is plausible
Existing service	The whole-home calculation and source panel support the added garage load	The service supports the larger load, or a coordinated service/energy-management plan is included
Feeder route	The electrician’s conductor and voltage-drop design works for the load and distance	A costly trench makes future feeder replacement worth avoiding, after engineering and cost review
Panel layout	The selected panel still has enough full-size spaces for the circuit plan	More spaces are needed, even if the final feeder rating is less than 100A

No single row decides the answer. A long run does not automatically require a 100A breaker, and an empty 100A panel does not prove the service can supply 100A. The final choice follows the load calculation and permitted design.

Copy this detached-garage load inventory

Fill in visible nameplate and manual information. Do not open a panel or remove equipment covers to find it.

Load or equipment	Voltage	Nameplate input A, VA, or W	Required circuit/manual note	Runs at the same time as	Present or future?
Interior and exterior lighting
General-use receptacles
Garage-door opener
Air compressor or dust collector
Welder
EV supply equipment
Mini-split, heater, or ventilation
Fixed tools, pumps, or appliances
Reserved future equipment

Then add three notes:

Worst realistic work session: Identify what could run together, such as welding while HVAC and dust collection operate.
Overnight scenario: Include EV charging, space conditioning, a freezer, battery chargers, or other unattended loads.
Future scenario: Name the actual equipment you are considering and the target year. “Maybe more tools” is not enough to size from.

Volts multiplied by input amperes can produce a planning value in volt-amperes when the nameplate provides both, but do not treat the sum as the permitted feeder load. Continuous loads, motors, welders, EV equipment, heating and cooling, nonlinear loads, demand factors, and manufacturer requirements can receive different code treatment. The panel load-calculation overview explains why breaker handles and nameplate values are not simply added.

Give EV, welder, and HVAC loads their own lines

These loads can change the answer quickly, but their largest advertised number is not always the right input.

EV charging

Record the EVSE’s selectable output, input rating, installation instructions, and the daily charging need. The U.S. Department of Energy notes that EV charging is treated as a continuous load and recommends an electrician verify available capacity and local permits. A lower charging setting or listed energy-management system may sometimes avoid oversizing, as explained in the EV load management versus panel upgrade guide.

Welder and motor-driven tools

Photograph the welder’s input nameplate and record its rated output and duty-cycle information. For compressors, dust collectors, lifts, and saws, record exact model and motor data. Do not substitute receptacle size, plug shape, or output amperage for actual input requirements.

Heating and cooling

For a mini-split or heat pump, use the matched equipment’s nameplate and installation manual. The electrician needs values such as minimum circuit ampacity and maximum overcurrent protection where provided—not Btu/h alone. Use the mini-split electrical planning checklist to gather the right documents.

Check the house before sizing the garage

The source panel needs both physical breaker space and calculated capacity; those are separate tests. The electrician should evaluate the entire dwelling service with existing HVAC, cooking, water heating, laundry, EV, spa, and other loads included.

The serving utility may also need to review its meter, service conductors, transformer, trench crossing, or separate-service rules. A larger garage feeder can trigger work far beyond the garage, so compare the full installed scope rather than panelboard prices.

Treat distance as a design input

Record the one-way route length, underground or overhead path, grade changes, vehicle areas, and surfaces that must be restored. Voltage drop depends on load, distance, conductor, and operating conditions. It can affect tool starting and equipment performance even when basic ampacity requirements are met.

Distance does not create a universal conductor-size or feeder-rating answer. A licensed electrician must coordinate ampacity, terminals, temperature limits, adjustment factors, wiring method, physical protection, voltage drop, and the adopted code. Do this before trenching; the garage electrical code guide covers the broader receptacle, protection, and layout context.

Keep grounding and bonding separate from capacity

A typical new detached-garage feeder includes two ungrounded conductors, a neutral, and an equipment grounding conductor. At the garage distribution panel, the neutral is generally isolated from the enclosure and equipment-grounding bar. The detached structure’s grounding electrode system is a separate requirement and does not replace the feeder equipment grounding conductor.

The building disconnect, neutral isolation, equipment grounding path, electrodes, surge protection, panel working space, and labels must be designed together. None of these features increases feeder capacity. Review the architecture in subpanel installation basics, then leave conductor terminations and panel work to a licensed electrician.

Confirm code edition, permit, listing, and AHJ rules

The NEC is a model code; the edition adopted at the project location, local amendments, and the authority having jurisdiction control. The 2026 NEC has been published, but adoption dates vary. For example, Washington L&I currently inspects to the 2023 NEC and says the 2026 edition is scheduled to replace it on December 31, 2026.

NFPA’s 2026 NEC feeder development record shows that feeder sizing coordinates load, continuous-load treatment, correction factors, and voltage-drop considerations. The Department of Energy’s home EV charging guidance separately emphasizes electrical-capacity review, listed equipment, local codes, and permits.

Before buying a panel or opening a trench, ask the AHJ which code edition applies, whether drawings or a load calculation are required, when inspections occur, and which local amendments matter. Confirm every breaker, panelboard, disconnect, EVSE, and other component is listed and used according to its instructions.

Next step: prepare an electrician-ready scope

Bring the completed load inventory, equipment manuals, one-way route measurement, visible photos of source-panel labels, garage layout, future-load scenario, and permit/AHJ notes to a licensed electrician. Ask for the quote to identify:

Calculated garage load and whole-service capacity
Proposed feeder rating and panelboard rating
Voltage-drop design basis
Number of usable full-size breaker spaces
Disconnect, grounding, bonding, and electrode scope
Utility coordination, permit, inspection, and trench responsibilities
An alternate 60A, 100A, or managed-load option where feasible

Use the electrician handoff checklist to organize the visit. The right detached-garage subpanel size is the smallest permitted design that supports documented present and future use without creating an expensive dead end.