Why heat matters here
Lancaster averages roughly 120 nights a year below freezing, with January lows around 20°F. A plug-in 1,500-watt space heater barely takes the edge off a two-car garage in that weather, and running one on an extension cord is a fire risk.
Choose the heater, then the circuit
Fixed heaters are a continuous load, so the circuit is sized at 125% of the heater's draw. The heater's installation manual has the final say.
| Heater | Voltage | Current draw | Typical circuit |
|---|---|---|---|
| 1,500 W portable | 120V | about 12.5 A | Its own 20-amp circuit; never an extension cord |
| 4,000 W unit heater | 240V | about 17 A | 25-amp, two-pole |
| 5,000 W unit heater | 240V | about 21 A | 30-amp, two-pole, 10-gauge wire |
| 7,500 W unit heater | 240V | about 31 A | 40-amp, two-pole |
| 10,000 W unit heater | 240V | about 42 A | 60-amp, two-pole |
| Mini-split heat pump | 240V | varies by model | Per the manufacturer, often a dedicated 15- to 25-amp circuit |
Insulation, door seals and ceiling height matter as much as wattage. A well-sealed garage needs a smaller heater.
and have the heater's model or wattage handy.
Will your panel handle it?
A 5,000-watt heater uses a meaningful share of a 100-amp service. Add an EV charger or a welder and the panel can run out of room. The electrician will run a load calculation and look at options:
- A dedicated heater circuit if there's capacity and space
- A garage subpanel if the garage also needs tools or a charger
- A smaller heater or a mini-split, which delivers more heat per watt
For detached garages, the heater circuit usually comes from a subpanel fed from the house; see detached garage electrical.
Mini-splits for a garage you use year-round
A ductless mini-split heats in winter and cools in summer, and it typically costs less to run than a resistance heater. It needs a dedicated 240-volt circuit and an outdoor disconnect, plus installation by an HVAC contractor. The electrician handles the circuit and disconnect.
Space heaters and extension cords
Portable heaters plugged into extension cords or power strips, or left near stored fuel and rags, are a well-known fire risk. If you use a portable heater in the garage, plug it directly into a wall outlet on a circuit with nothing else heavy on it, or replace it with a hardwired unit.
Permits
A hardwired heater on a new circuit needs an electrical permit inside Lancaster city limits, and the work is inspected.
What garage heater wiring costs
National 2026 estimates; your electrician prices the actual job:
| Job | Typical range |
|---|---|
| Install a 240V garage heater circuit | $200 to $500 for the installation |
| New 240-volt circuit, generally | $250 to $800 |
| Mini-split, professional installation | $1,000 to $3,000 |
Running a 5,000-watt heater costs about 80 cents an hour at the national average electricity rate.
What moves the price: distance from the panel, heater size, whether the panel has room or needs a subpanel, and mounting height.
Get your garage ready for winter
Tell us the heater you're considering and your panel size.
Frequently Asked Questions
It depends on insulation and how warm you want it. Use the heater maker's sizing guide, and remember that sealing and insulating the garage often lets you buy a smaller heater on a smaller circuit.
Only if the heater is designed to plug in and the outlet and breaker match its rating. Most 240-volt unit heaters are designed to be hardwired.
Most unit heaters include one or support a wall thermostat. A thermostat keeps the garage just above freezing when you're not using it, which protects stored paint and liquids.
Early fall. Electricians get busy once the first hard freeze arrives.
Related services: Garage subpanel · Detached garage electrical · Workshop and 240V outlets
Serving Lancaster and nearby Fairfield County, including the rural townships, where many shops and pole barns need heat.