EV charger detached garage: power, trenching & costs
Running power for an EV charger detached garage? Compare trenching vs. overhead feeds, subpanel sizing, burial depths, 2026 costs, and future-proofing tips.
8 MIN READ · UPDATED 2026-09-19
Key takeaways
- Trenching underground conduit is the default for most properties; overhead feeds only work where clearances and local code allow.
- Install a subpanel (60–100A) rather than a single circuit so the garage can grow with future needs.
- NEC burial depths depend on wiring method and location — your electrician selects the conduit type and depth.
- Distance, soil conditions, and main-panel capacity are the three biggest cost drivers.
- While the trench is open, upsize the conduit and add a spare EV circuit — digging twice costs far more.
A detached garage is a great place to charge an EV — out of the weather, with room for a wall-mounted charger and proper cable management — but it comes with a project attached: getting serious electrical power from your house to a building that may sit 30, 60, or 100 feet away. For most homeowners that means trenching an underground conduit across the yard, setting a subpanel in the garage, and dedicating a circuit to the charger. Done right, it is a one-time project that serves the garage for decades; done on the cheap, it is the thing you pay to dig up twice.
This guide covers the decisions that matter: trenching versus overhead feeds, how to size the garage subpanel, what the National Electrical Code says about burial depths (in general terms — your electrician owns the details), the real cost drivers in 2026, whether to rough in a second EV circuit while the ground is open, and the wireless and load-management options that can shrink the scope of the work.
Trenching vs. overhead feeds
Underground conduit is the default for good reasons: it is protected from weather and physical damage, it does not clutter the sightlines of your yard, and most inspectors and neighbors prefer it. The trade-off is digging — through lawn, landscaping, and sometimes driveways — plus the cost of the trench itself, which rises with every foot. Before anyone digs, your contractor calls 811 (or the local one-call service) to mark buried utilities; hitting a gas or telecom line turns a straightforward job into an expensive emergency.
An overhead feed — a cable run from the house to a mast on the garage — avoids digging entirely, which makes it tempting where bedrock or dense tree roots make trenching brutal. But it only works when clearances over driveways, walkways, and neighboring property meet code, when the local authority having jurisdiction allows it, and when you can live with a wire crossing your yard. Many suburban AHJs discourage new overhead residential feeds for aesthetic reasons. Your electrician and the inspector make this call together; where trenching is feasible, it is almost always the recommended path.
Sizing a subpanel in the garage
Resist the urge to run a single dedicated circuit for today's charger and call it done. A subpanel in the garage — typically fed at 60 or 100 amps — gives you a proper distribution point for the EV circuit plus lighting, receptacles, and workshop tools, all protected locally. A 60-amp feeder comfortably supports one 48-amp EV charger (the largest common home charging rate, which requires a 60-amp circuit under continuous-load rules), while a 100-amp feeder leaves headroom for a second EV circuit later without touching the yard again.
What the main panel can actually spare is determined by an NEC load calculation, which your electrician performs based on your home's existing loads and service size. If the numbers are tight, that is not the end of the project — energy management devices recognized by the NEC can let the EV charger use spare capacity dynamically, avoiding a full service upgrade. The key point: size the trench and conduit for the feeder you might want in ten years, not just the charger you are buying this year.
Conduit runs and burial depth
The NEC sets minimum burial depths — technically "cover" requirements — that vary with the wiring method and where the run passes: deeper under driveways and parking areas, shallower under a simple lawn. The exact numbers depend on whether your electrician uses PVC conduit, rigid metal conduit, or another approved method, and local amendments can add their own twists. This is squarely the professional's territory: specify the outcome you want (a code-compliant, inspectable underground feed) and let the licensed electrician select the conduit type, depth, and fittings.
A few details are worth discussing with your contractor anyway. One continuous conduit run with minimal bends pulls wire far more easily than a tortuous path. Consider a second, smaller conduit in the same trench for future low-voltage needs like network cable or gate controls — the incremental cost while the trench is open is tiny. And plan the route to avoid mature tree roots and future landscaping projects. None of this is DIY guidance: trenching near utilities and terminating feeders is licensed-electrician work, permitted and inspected like any service upgrade.
What drives the cost
Three variables dominate the budget: distance, digging conditions, and panel capacity. A 30-foot trench through soft loam is a fundamentally different job than a 120-foot run through rocky soil under a concrete driveway. If your main panel is full or the service cannot absorb the new load, a panel upgrade or energy management hardware enters the picture. Permits, inspections, and siding or drywall repairs at both ends round out the invoice.
| Cost component | Typical 2026 US range | Notes |
|---|---|---|
| Trenching, easy soil | $8–$20 per linear foot | Machine or hand digging through lawn and loam |
| Trenching, rocky soil or rock | $25–$60+ per linear foot | Rock sawing or hammering; have soil conditions assessed |
| Driveway or sidewalk crossing | $1,000–$3,000 | Boring underneath, or cutting and repouring concrete |
| Feeder wire and conduit (materials) | $6–$15 per linear foot | Varies with feeder size and copper pricing |
| Garage subpanel and feeder breaker | $800–$2,000 installed | 60–100A panel with proper grounding electrode |
| EV charger circuit from subpanel | $400–$900 | Breaker, wiring, and hardwired connection or receptacle |
| EV charger unit | $400–$700 | Verify manufacturer spec sheets; features and compatibility vary by model year and market |
| Permit and inspections | $150–$600 | Varies widely by municipality |
| Main panel upgrade (if needed) | $2,500–$6,000 | Only when the load calculation requires it |
All in, most detached-garage EV projects land between $3,500 and $12,000, with short easy runs at the low end and long rocky runs needing panel work at the high end. Costs are 2026 US market ranges; get itemized local quotes.
Future-proofing: should you add a second EV circuit?
If there is any chance of a second EV in the household's future — and statistically, there is — the cheapest time to prepare is while the trench is open. Upsizing from a 60-amp to a 100-amp feeder, pulling heavier wire, and using larger conduit adds hundreds, not thousands, to the project. Some homeowners even have the electrician rough in the second charger circuit, breaker space and all, so adding the second unit later is a half-day job.
You do not necessarily need double the electrical capacity to charge two cars. Load-sharing chargers can split a single feeder between two vehicles, and scheduled overnight charging means each car can take its turn. Confirm before buying that the chargers you choose support whatever sharing or management scheme you plan — compatibility varies by model year and market, so verify against manufacturer spec sheets rather than assuming any two units will cooperate.
Wireless and load-management options
When people ask about "wireless" EV charging for a detached garage, they usually mean one of two things: avoiding a control-wire run, or avoiding the trench altogether. True wireless power transfer for cars exists but remains a niche, expensive technology — not a practical 2026 retrofit. The realistic wireless story is about monitoring and control: several energy management devices use a wireless current sensor clamped at the main panel that talks to the EV charger, letting the charger throttle itself based on whole-house demand without running low-voltage control wire across the yard.
These NEC-recognized energy management systems are genuinely useful when your service is maxed out: they can green-light an EV charger that a plain load calculation would reject, saving the cost of a service upgrade. But be clear about what they do not do — you still need the power feed itself from house to garage. Where they shine is shrinking the electrical scope: no new service, no utility coordination, just smarter use of the capacity you already have.
Trench once and trench big. Opening the ground is the most expensive part of powering a detached garage — upsizing the conduit and adding a spare circuit while it's open costs a fraction of digging a second time.
Hiring the right electrician
Get at least two itemized quotes from licensed electricians with EV and trenching experience, and make sure each one covers the load calculation, permit, trenching and restoration, subpanel, charger circuit, and inspection — not just the charger hookup. Ask how they handle utility locates, what depth and conduit they plan to use, and whether they have worked with your local inspector on similar runs. A contractor who answers those questions crisply is one who has done this before.
Frequently asked questions
Sometimes. An overhead feed avoids digging, which helps where bedrock or dense roots make trenching punishing — but it must meet code clearances over driveways and walkways, and your local authority having jurisdiction has to allow it. Many suburban municipalities discourage new overhead residential feeds for aesthetic reasons. Have your electrician and the inspector evaluate both options before you commit.
The NEC specifies minimum cover depths that vary with the wiring method — for example, PVC conduit versus rigid metal — and with the location, such as under a lawn versus under a driveway. Local amendments can modify these requirements, so there is no single number to memorize. Your licensed electrician selects the conduit type and depth to satisfy both the NEC and your local inspector. Always call 811 for a utility locate before any digging begins.
A 60-amp feeder is the practical minimum, since a 48-amp charger — the fastest common home charging rate — requires a 60-amp circuit under continuous-load rules. Most electricians recommend a 100-amp subpanel instead, which covers the charger plus lighting, tools, and a future second EV circuit. An NEC load calculation on your main panel determines what your service can actually spare.
Most complete projects fall between $3,500 and $12,000, driven mainly by trench distance, soil conditions, and whether your main panel needs an upgrade. Short runs through easy soil sit at the low end; long runs through rock or under concrete, plus panel work, reach the high end. Costs are 2026 US market ranges; get itemized local quotes.
If a second EV is even remotely likely, yes. Upsizing the feeder and conduit and roughing in the extra circuit while the trench is open adds hundreds of dollars versus thousands for a second dig later. Load-sharing chargers can even split one feeder between two cars, so you may not need double the capacity. Just verify charger compatibility against manufacturer spec sheets before committing to a sharing scheme.
Yes. Running a new feeder to a detached garage requires an electrical permit and inspection in virtually every jurisdiction, and the work must be performed by a licensed electrician. The permit process also triggers the utility locate and confirms your installation meets NEC burial, grounding, and disconnect requirements. Unpermitted electrical work can void your homeowner's insurance and create major problems when you sell.