Signs you need a garage subpanel
- Your main panel has no open spaces, or has "cheater" breakers squeezed in to make room.
- Garage breakers trip whenever a compressor, saw or heater runs.
- You're adding several new garage circuits at once: a charger, a heater, tool outlets.
- Your detached garage runs on one circuit and you want real power out there.
- You'd like to shut off the garage's power without walking back to the house.
60A, 100A or 125A?
| Subpanel size | Typically supports | Common use |
|---|---|---|
| 60 amps | Lights, general outlets, one or two 240-volt tools used one at a time | Hobby workshop, light storage garage |
| 100 amps | All of the above plus an EV charger or a 240-volt heater | Most "do everything" garages |
| 125 amps and up | Several heavy loads at once | Large shops, multiple chargers, garages with living space above |
The step from 60 to 100 amps usually adds little to material cost, while upgrading later means replacing the feed. The size that actually matters is the breaker feeding the subpanel and the wire to it; the subpanel itself can be rated higher.
and tell us what you plan to run.
Can your main panel support a subpanel?
A subpanel shares your home's existing service. If the house already uses most of a 100-amp service, a 100-amp garage subpanel doesn't make more power appear. The electrician will:
- Run a load calculation on the whole house.
- Check for two open spaces for the feeder breaker.
- Confirm the panel's condition, since some older panels are worth replacing rather than extending.
If there isn't enough capacity, the options are a smaller subpanel, load-managed equipment such as a smart EV charger, or a service upgrade. For a service upgrade in Lancaster, the power company reconnects only after the city's inspector approves the new service.
Attached vs. detached garage subpanels
Attached garage: the subpanel is usually close to the main panel, often on the garage side of a shared wall. The feed is short and the job is simpler.
Detached garage: the feed runs underground or overhead, and the garage needs its own grounding electrode, a four-wire feeder with neutral and ground kept separate, and a disconnect, usually a main breaker in the subpanel. See running power to a detached garage.
What installation involves
- Load calculation and sizing
- Permit from the City of Lancaster Certified Building Department (or the office covering your address outside the city)
- Feeder breaker in the main panel and feeder wire to the garage
- Mount the subpanel and land the circuits
- Label every breaker; Lancaster's inspectors expect a clear circuit directory
- Inspection
What a garage subpanel costs
National 2026 estimates; your electrician prices the actual job:
| Job | Typical installed range |
|---|---|
| 60A subpanel, attached garage | $500 to $900 |
| 100A subpanel, attached garage | $1,000 to $2,500 |
| Subpanel in a detached garage with an underground run | $1,500 to $4,000+ |
What moves the price: feeder length and wire size, trenching, the number of new circuits added at the same time, and whether the main panel needs work first.
Out of breaker space?
Tell us your main panel size and what you want to add.
Frequently Asked Questions
No. It adds breaker spaces and puts the garage's circuits in one place. Total capacity is still set by your main service.
Yes. The breaker and the feeder wire set what the garage can draw; the subpanel can be rated higher. That makes it easy to increase the feed later if you upgrade your service.
No. An attached garage shares the house's grounding system. A detached garage fed by a subpanel needs its own.
Yes. New feeders and circuits require an electrical permit inside city limits, and the work is inspected.
Related services: Detached garage electrical · EV charger installation · Garage heater wiring · Workshop and 240V outlets
Serving Lancaster and nearby Fairfield County, including the East Side and Lanreco Park, where many mid-century homes need a capacity check first.