A subpanel in a detached garage is fed from your home’s main panel through a buried 4-wire feeder, and a 100-amp subpanel handles almost any workshop, heater, or EV charger you’ll add later. Most homeowners pay roughly $1,000 to $3,000 installed and hire a licensed electrician for the main-panel tie-in. The trenching is often the DIY-friendly part.
TL;DR: Run a 4-wire feeder (two hots, neutral, separate ground) from the main panel to a 60-amp or 100-amp subpanel in the garage. Keep neutral and ground isolated, drive one or two ground rods, and bury the line 18 to 24 inches deep. Budget $1,000 to $3,000 and pull a permit.
If your garage needs more than a single 20-amp circuit, yes. A subpanel gives you room for lighting, outlets, a heater, and a dedicated EV or tool circuit without daisy-chaining everything onto one overloaded line. Running a single circuit out to the garage works for a light and a couple of outlets, but it falls apart the moment you plug in a compressor or a space heater.
The smarter move is to size for what you’ll want in five years, not just today. Getting power across the yard is one piece of the larger job of connecting a detached garage to the house, so plan the panel once and you won’t be trenching twice.
Match the amperage to the load you actually plan to run. A few outlets and lights need very little. A heated workshop with an EV charger needs real capacity, and undersizing is the regret people mention most.
| Subpanel size | Typical garage use |
|---|---|
| 50A | Lights, outlets, a small heater, occasional power tools |
| 60A | Workshop tools, a modest heater, basic shop equipment |
| 100A | Full workshop, electric heater, EV charger, future expansion |
For most people, 100 amps is the right call. The cost difference over 60 amps is modest at install time, and it spares you from a second project when you add an EV charger or a real heat source. A serious heat source pulls real amperage, so how you plan to heat the space depends partly on how much power you can run out there.
Older detached garages were often wired with three wires, bonding neutral and ground together at the subpanel. Modern code does not allow that. The feeder now carries four wires: two hots, a neutral, and a separate equipment ground.
At the subpanel, neutral and ground must stay separate. That means the neutral bar is isolated (its bonding screw removed) and the ground bar is bonded to the enclosure. Getting this backward is one of the most common reasons an inspection fails, so it’s worth confirming before you close anything up.
The detached building also needs its own grounding electrode. Code (NEC 250.32) requires one or two ground rods driven at the garage, tied to the ground bar in the subpanel. This is separate from the ground wire in the feeder, and skipping it is not optional.
The feeder runs underground from the house to the garage, either as direct-burial cable or as conductors pulled through conduit in a trench. Burial depth depends on the method and your local code, but 18 to 24 inches is the common range. Conduit generally allows a shallower trench than direct burial; check what your inspector expects before you dig.
This is where many homeowners save money. The trenching and conduit work is often DIY-friendly where local code allows, while the actual panel connections stay with a pro. Digging your own trench can shave a meaningful chunk off the labor bill, which matters when you are weighing the full cost of the build.
A permit and inspection are required for this work. That isn’t bureaucratic busywork; it’s the step that confirms your grounding and wire sizing are safe.
Be honest about the split. The main-panel connection means working in a live service panel, and that’s where most homeowners should stop and call a professional. The risk of a mistake there is shock, fire, or a failed inspection that costs more to undo than to do right.
A reasonable middle path: you handle the trench and conduit, and a licensed electrician makes the panel connections and signs off. Confirm licensing and insurance before anyone touches your service, since a qualified pro is the difference between a clean inspection and an expensive redo, which is exactly the point this guidance on hiring a licensed electrical contractor makes. Get the permit, agree on who does what in writing, and you keep both your money and your safety margin.
If you want more than one or two circuits, yes. A subpanel lets you run lighting, outlets, a heater, and a dedicated tool or EV circuit without overloading a single line. For just a light and an outlet, a single circuit can work, but most garages outgrow that fast.
Yes. Modern code (NEC 250.32) requires a detached building to have its own grounding electrode, typically one or two ground rods driven at the garage. This is in addition to the ground wire in the feeder, not a replacement for it.
A 60-amp subpanel covers a workshop with tools and a modest heater. A 100-amp subpanel is the better choice if you plan to run an electric heater, an EV charger, or want room to grow. Most people are happiest sizing up to 100 amps.
Expect roughly $1,000 to $3,000 installed, though it varies widely with the distance from the main panel and the amperage you choose. Doing your own trenching where code allows can lower the labor portion of that bill.
Andy Wu is the resident backyard products expert and hails from Atlanta, Georgia. His passion for crafting outdoor retreats began in 2003.
As a fellow homeowner, he founded Backyard Oasis to provide top-quality furnishings and equipment, collaborating with leading manufacturers.
His main focus is on sheds and generators!
In his spare time he like to hike the tallest mountains in the world and travel with his family.
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