A detached garage can be a great place for Level 2 EV charging, but it is not always as simple as mounting a charger on the wall. Because the garage is separate from the house, the job may involve underground conduit, a subpanel, longer wire runs, weather exposure, permits, and utility rules. This checklist helps you understand what to gather before calling electricians, what questions to ask, and when a panel upgrade may or may not be necessary.

This is not a do-it-yourself wiring guide. EV charging is a continuous high-power electrical load, and detached structures add extra code considerations. Use this page to prepare, compare quotes, and avoid surprises; have the actual electrical work designed, permitted, and completed by a licensed electrician.

1. Confirm what charging speed you actually need

Before assuming you need the largest charger available, estimate your daily driving and overnight charging window.

Most homeowners considering Level 2 charging are choosing between charging circuits that commonly support about 16 to 48 amps of charging output, depending on the charger, circuit size, wiring, and electrical capacity. Higher amperage can add range faster, but it can also increase installation cost, trigger panel-capacity concerns, or require heavier wiring to a detached garage.

Ask yourself:

  • How many miles do you usually drive per day?
  • Can the car charge overnight for 8 to 12 hours?
  • Will one EV charge there, or might two EVs share the space later?
  • Does your vehicle have a maximum onboard AC charging rate that limits how much power it can use?
  • Would a lower-power Level 2 setup still fully recharge your normal daily use?

A good electrician should not just quote the biggest circuit by default. They should help match charging capacity to your car, driving habits, panel capacity, and future plans.

2. Locate the main electrical panel and any garage subpanel

Detached garages are wired in different ways. Some have only a small lighting-and-outlet feed. Others have a subpanel with spare capacity. Some older garages may have wiring that is not suitable for EV charging without significant upgrades.

Before requesting quotes, take clear photos of:

  • The main electrical panel with the door open
  • The panel label or breaker schedule, if readable
  • The main breaker rating
  • Any subpanel inside the detached garage
  • The breaker feeding the garage, if you can identify it safely without removing covers
  • The path between the house and garage

Do not remove panel covers or touch wiring. Photos of the existing panels and labels are usually enough for an electrician to start the conversation.

3. Ask for a load calculation, not just a guess

A panel upgrade quote should be based on a proper electrical load calculation, not only on whether the panel “looks full.” A full-looking panel may still have options, while a panel with empty breaker spaces may still lack enough capacity.

Ask each electrician:

  • Will you perform a load calculation under the locally adopted electrical code?
  • Does the calculation include existing large loads such as HVAC, electric range, dryer, water heater, pool equipment, hot tub, or workshop tools?
  • Are there code-compliant alternatives to a full service upgrade, such as a lower-amperage charger, energy management system, load-sharing charger, or using an existing garage subpanel if adequate?
  • If a panel or service upgrade is recommended, what specific calculation or utility requirement makes it necessary?

Rules vary by jurisdiction, and the National Electrical Code is adopted and amended locally. Your city, county, and utility may also have requirements that affect the answer.

4. Understand the detached-garage complications

The distance from the main panel to the garage is one of the biggest cost drivers. If there is not already adequate capacity in the garage, the electrician may need to run a new feeder or circuit from the house to the detached structure.

Items that can affect cost and design include:

  • Trenching distance between buildings
  • Existing concrete, pavers, landscaping, driveways, or retaining walls
  • Required burial depth and conduit type under local code
  • Whether the route crosses utility lines
  • Whether the garage needs a subpanel upgrade
  • Grounding and bonding requirements for a detached structure
  • Weather-rated equipment if the charger is exposed
  • Physical protection from vehicles, tools, or snow removal equipment

Before any digging, underground utilities must be located through the proper local utility-marking service. Your electrician or trenching contractor should know the process in your area.

5. Decide on hardwired versus plug-in charging

Many Level 2 chargers can be installed either hardwired or with a plug, depending on the model and local code. For detached garages, hardwired installation is often cleaner and may support higher charging output, but the best choice depends on the charger, circuit, local rules, and whether you value portability.

Ask your electrician:

  • Is this charger approved for hardwired installation, plug-in installation, or both?
  • Does local code require GFCI protection for this configuration?
  • Would a receptacle introduce nuisance-tripping or weatherproofing concerns?
  • What maximum charging output is allowed with this installation method?
  • If I replace the charger later, how difficult will that be?

Do not install or modify a high-voltage receptacle yourself. Incorrect EV charger receptacle installations can overheat, fail, or create shock and fire hazards.

6. Check permits, inspections, and utility rules

EV charger installations often require an electrical permit and inspection. Detached garages, trenching, subpanels, and service upgrades make permitting more likely, not less.

Before accepting a quote, ask:

  • Will the electrician pull the permit?
  • Is inspection included in the price?
  • Does the utility need to approve a service upgrade or meter work?
  • Are there time-of-use EV rates available?
  • Does the utility offer charger rebates, make-ready wiring rebates, or panel-upgrade incentives?
  • Are there charger models required for rebate eligibility?

Rebates change frequently and may depend on your utility, income qualification, charger model, permit status, installation date, and whether the charger can share charging data. Verify directly with your utility, state energy office, local air district, or municipal program before buying equipment.

7. Prepare information before requesting electrician quotes

You will get better quotes if you provide the same information to each electrician. Send a short package with:

  • Your vehicle make and model, or expected EV
  • Charger model, if already chosen
  • Desired charger location in the detached garage
  • Photos of main panel, garage subpanel, and panel labels
  • Approximate distance from house panel to garage charger location
  • Photos of the likely trench path and obstacles
  • Whether you want future two-EV capacity
  • Any known plans for solar, battery storage, heat pump, hot tub, or electric appliance upgrades

If you do not know the charger model yet, say so. A good electrician can quote options and explain tradeoffs.

8. Compare quotes by scope, not just price

Detached-garage EV charger quotes can vary widely because contractors may include different assumptions. A low quote that excludes trenching, permits, patching, or inspection may not be cheaper in the end.

Compare whether each quote includes:

  • Load calculation
  • Permit and inspection
  • Trenching and backfill
  • Conduit and wiring from house to garage
  • Subpanel work, if needed
  • Charger mounting and commissioning
  • GFCI or other required protection
  • Weatherproofing and physical protection
  • Utility coordination, if needed
  • Cleanup and restoration limits
  • Warranty on labor and materials

Ask for the quote to state charger amperage, circuit size, installation method, and what is excluded.

9. Red flags to watch for

Be cautious if someone:

  • Says no permit is needed without checking local rules
  • Recommends a panel upgrade without a load calculation
  • Dismisses trenching, grounding, or detached-structure requirements as unimportant
  • Wants to reuse unknown old garage wiring for a high-power charger
  • Cannot explain charger amperage versus circuit size
  • Will not specify whether inspection is included
  • Suggests homeowner wiring work to save money

You do not need to become an electrician, but you do need enough information to know whether the proposal is careful.

10. A practical decision path

Use this simple sequence before approving work:

  1. Estimate your daily charging need.
  2. Choose a likely charger power range, not necessarily the maximum.
  3. Gather panel, garage, and route photos.
  4. Ask for quotes that include a load calculation.
  5. Confirm permit, inspection, and utility requirements.
  6. Check rebates before buying the charger.
  7. Compare full scope, exclusions, and upgrade justification.
  8. Approve only after you understand why the proposed design fits your home.

A detached garage EV charger can be straightforward, or it can become a small electrical infrastructure project. The difference usually comes down to distance, existing capacity, local code, and how carefully the job is scoped before work begins.