A dedicated circuit is one breaker that serves one appliance or one required group of outlets and nothing else. In a modern house, these need one:
- Always, by code: the furnace or air handler, the air conditioner or heat pump, the water heater, an EV charger, and the required 20 amp circuits for laundry, bathroom and garage receptacles.
- In practice, by size or by the manufacturer's instructions: the range, cooktop or wall oven, the dryer, the dishwasher, the disposal, an over-range microwave, and often the refrigerator.
The size of each circuit comes from the appliance's nameplate. NEC 110.3(B) requires equipment to be installed following its listing and instructions, so when an installation manual says "dedicated 20 amp circuit," that becomes a code requirement.
Circuits the NEC requires by location
NEC 210.11(C) requires these receptacle circuits in dwellings:
- Kitchen and dining: at least two 20 amp small-appliance circuits. See kitchen circuit requirements.
- Laundry: at least one 20 amp circuit for the laundry receptacles, serving no other outlets.
- Bathrooms: at least one 20 amp circuit for the bathroom receptacles. It can serve the receptacles in several bathrooms, or everything in one bathroom, but not other rooms.
- Garage: in each attached garage, and in detached garages with power, at least one 20 amp circuit for the receptacles, serving no outlets outside the garage. This was added in the 2020 NEC.
Circuits the NEC requires by equipment
Central heating. NEC 422.12 requires central heating equipment, such as a furnace or air handler, to be on an individual branch circuit. Auxiliary equipment directly connected to it, such as a humidifier or a condensate pump, can share it.
Air conditioners and heat pumps. NEC Article 440 sizes the circuit from two numbers on the nameplate: minimum circuit ampacity (MCA), which sets the wire size, and maximum overcurrent protection (MOP or MAX FUSE/BREAKER), which sets the largest breaker allowed. The outdoor unit needs its own 240 volt circuit and a disconnect within sight of the unit.
In the example nameplate, MCA 18.5 means 12 AWG copper (rated 20 amps) is the minimum wire, and MAX 30 means the breaker can be up to 30 amps. The breaker can be larger than the wire's normal rating here because Article 440 covers motor starting current differently from general circuits.
Heat strips. A heat pump's air handler with electric backup heat usually needs its own large circuit, often 40 to 60 amps for 8 to 10 kW of strips, sized from the air handler's nameplate. This is one of the biggest loads in an all-electric house. See will a 100 amp service run a heat pump.
Water heaters. NEC 422.13 treats a storage water heater of 120 gallons or less as a continuous load, so the circuit is sized at 125% of its rating. A common 4,500 watt, 240 volt element draws 18.75 amps; 125% is 23.4 amps, so a 30 amp circuit on 10 AWG copper. Tankless electric water heaters are much larger, often needing two or three 40 to 60 amp circuits.
EV chargers. NEC 625.40 requires each outlet installed for EV charging to be supplied by an individual branch circuit, and EV charging is treated as a continuous load, so the circuit is sized at 125% of the charger's current. A charger set to 48 amps needs a 60 amp circuit. See EV charger electrical requirements.
Pools, spas and hot tubs have their own rules in NEC Article 680, with GFCI protection and disconnects.
Circuits by appliance, typical sizes
| Appliance | Voltage | Typical breaker | Why dedicated |
|---|---|---|---|
| Heat pump or AC outdoor unit | 240 V | 15 to 60 A, per nameplate MOP | Article 440 |
| Air handler with heat strips | 240 V | 40 to 60 A, per nameplate | Size of load |
| Gas furnace blower and controls | 120 V | 15 or 20 A | 422.12 |
| Tank water heater, 4,500 W | 240 V | 30 A | 422.13 |
| EV charger at 48 A | 240 V | 60 A | 625.40 |
| Electric range | 240 V | 40 or 50 A | Size of load |
| Electric dryer | 240 V | 30 A | Size of load |
| Dishwasher | 120 V | 15 or 20 A | Manufacturer |
| Disposal | 120 V | 15 or 20 A | Manufacturer |
| Over-range microwave | 120 V | 20 A | Manufacturer |
| Refrigerator | 120 V | 15 or 20 A | Optional, allowed by 210.52(B) |
| Well pump | 240 V | per pump nameplate | Size of load |
Does a heat pump need its own circuit?
Yes. The outdoor unit of a heat pump or air conditioner needs its own 240 volt circuit sized from its nameplate MCA and MOP, and a disconnect within sight of the unit. The indoor air handler or furnace needs its own circuit too, and if it has electric heat strips, that circuit is often the largest one in the house. A ductless mini-split's outdoor unit also needs its own circuit; the indoor heads are usually fed from the outdoor unit.
Mini-splits and window units
A window air conditioner rated 120 volts can plug into a general-purpose receptacle if its current is within the circuit's limits; NEC 440.62 limits a cord-connected unit to 80% of the circuit rating when it is the only load, and 50% when the circuit also supplies lights or other outlets. Larger window units are 240 volt and need their own circuit. Ductless mini-split outdoor units always need a dedicated circuit sized from their nameplate.
Refrigerators and freezers
The NEC does not require a dedicated refrigerator circuit. It does allow the refrigerator to be on an individual 15 amp or larger circuit instead of the kitchen's small-appliance circuits. Many electricians install one anyway, so a tripped countertop circuit does not stop the refrigerator.
A freezer in a garage or basement plugs into a receptacle that needs GFCI protection. Modern GFCI devices rarely trip on a healthy freezer, but a trip can go unnoticed for days. Some owners put a freezer alarm on it.
How many panel spaces this takes
Each 240 volt circuit takes two spaces in the panel. An all-electric house quickly fills a small panel.
Six large 240 volt loads use twelve spaces before any 120 volt circuit. Add two kitchen countertop circuits, laundry, bathrooms, garage, and a dozen lighting and receptacle circuits, and a 30 space panel is full. That is why many electrifying houses need a 40 or 42 space panel, a subpanel, or load management. See what to do when a panel is full and electrifying a house.
Planning ahead when a panel is replaced
The cheapest time to add a dedicated circuit is when the panel is replaced or the walls are open. Electricians often suggest adding, at that time, a 240 volt circuit to the garage for a future EV charger, a circuit to the likely location of a future heat pump, and a spare 240 volt circuit to the kitchen if the house still cooks with gas. Running the cable now and leaving it capped in a labeled box costs a fraction of fishing it later.
It also helps to leave spaces in the panel. A panel filled to the last space on day one has no room for the next appliance. For an all-electric house, 40 to 42 spaces is a common target.
240 volt versus 120 volt
Large heating and motor loads run on 240 volts because the same power draws half the current. A 4,500 watt water heater draws 18.75 amps at 240 volts; at 120 volts it would draw 37.5 amps and need much larger wire. That is why ranges, dryers, water heaters, heat pumps and EV chargers are 240 volt circuits, each using two panel spaces, while most receptacles and lights stay at 120 volts.
Who does this
Adding a circuit means working in the panel and running cable. Most jurisdictions require a permit and many require a licensed electrician. Before adding large 240 volt loads, a load calculation shows whether the service can carry them. Our service size calculator runs that calculation.
FAQ
Does a microwave need a dedicated circuit? An over-range or built-in microwave usually does, per its instructions. A countertop microwave plugs into a kitchen countertop circuit.
Does a dishwasher need its own circuit? Most manufacturers call for one. Some allow sharing with the disposal. Local codes sometimes require separate circuits.
Can a washer and dryer share a circuit? No. The washer plugs into the 20 amp laundry circuit; an electric dryer needs its own 240 volt, typically 30 amp circuit. A gas dryer can plug into the laundry circuit.
Does a sump pump need a dedicated circuit? The NEC does not require one, but manufacturers often recommend it so another load cannot trip the pump's breaker.