Standard Circuit Breaker Sizes (NEC 240.6)
The complete list of standard circuit breaker and fuse ampere ratings from NEC 240.6(A), plus a residential breaker size chart matching each breaker to the correct copper wire gauge and typical circuits.
What Are Standard Breaker Sizes?
Circuit breakers are manufactured in standard ampere ratings defined by NEC 240.6(A).These standard sizes matter because overcurrent protection rules throughout the Code — including the next-size-up rule of 240.4(B) — are written around them. When a load calculation lands between two standard ratings, the Code tells you which one you're allowed to use.
In residential work you'll see a handful of sizes over and over: 15 and 20 amps for lighting and receptacle circuits, 30 through 60 amps for appliance and equipment circuits, and 100 through 200 amps for main services and subpanel feeders. Commercial and industrial distribution uses the larger ratings, all the way up to 6000 amps.
The breaker's job is to protect the wire, not the appliance — so every breaker size is tied to a minimum conductor size. Use our breaker size calculator to size a breaker from your load, or the wire ampacity chart to match wire to breaker.
Complete List of Standard Breaker Sizes — NEC 240.6(A)
Standard ampere ratings for fuses and inverse-time circuit breakers, grouped by typical application
| Class | Standard Ampere Ratings | Typical Applications |
|---|---|---|
| Residential branch circuits | 15, 20, 25, 30, 35, 40, 45, 50, 60 A | Lighting, receptacles, appliances, dryers, ranges, water heaters, EV chargers |
| Large branch circuits, feeders & small services | 70, 80, 90, 100, 110, 125, 150, 175, 200 A | Subpanels, HVAC equipment, residential main services (100–200A) |
| Large services & commercial feeders | 225, 250, 300, 350, 400, 450, 500, 600 A | Large residential and light commercial services, panelboard mains |
| Industrial & main distribution | 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000, 5000, 6000 A | Switchgear, service entrance equipment, industrial distribution |
Note:NEC 240.6(A) also lists 1, 3, 6, 10, and 601 amps as additional standard ratings for fuses. The use of fuses and circuit breakers with nonstandard ampere ratings is permitted, but they are rarely manufactured — in practice, stick to the standard sizes above.
Common Residential Breaker Sizes and Their Uses
Copper wire sizes per NEC Table 310.16 (75°C column) and the small-conductor limits of NEC 240.4(D) for #14, #12, and #10 AWG
| Breaker Size | Copper Wire Size | Type | Typical Uses | NEC Basis |
|---|---|---|---|---|
| 15A | #14 copper | Single-pole | Lighting circuits, general receptacles | 240.4(D) limits #14 Cu to 15A |
| 20A | #12 copper | Single-pole | Kitchen small-appliance, bathroom, laundry, garage receptacles | 240.4(D) limits #12 Cu to 20A |
| 30A | #10 copper | Double-pole | Electric dryer, water heater | 240.4(D) limits #10 Cu to 30A |
| 40A | #8 copper | Double-pole | Electric range, cooktop | #8 Cu = 50A at 75°C |
| 50A | #6 copper | Double-pole | Large range, EV charger, hot tub | #6 Cu = 65A at 75°C |
| 60A | #6 copper | Double-pole | Subpanel feeder, tankless water heater | #6 Cu = 65A at 75°C |
| 100A | #3 copper | Double-pole | Subpanel feeder, small main service | #3 Cu = 100A at 75°C |
| 200A | 2/0 copper | Double-pole (main) | Main service panel | Per NEC 310.12 (83% rule) for dwelling services |
Small-conductor rule: NEC 240.4(D) caps overcurrent protection at 15A for #14 copper, 20A for #12 copper, and 30A for #10 copper — even though Table 310.16 lists higher ampacities for those wires. Always verify wire size on our wire ampacity chart before selecting a breaker.
How to Size a Breaker
Calculate the load current
Find the circuit's amperage from the load: Amps = Watts ÷ Volts. For a mix of loads, add up the full-load currents.
Apply 125% for continuous loads
Per NEC 210.20(A), the breaker must be rated at least 125% of the continuous load (any load expected to run 3 hours or more — EV chargers, water heaters, lighting) plus 100% of the noncontinuous load. Example: a 32A continuous EV charging load requires 32 × 1.25 = 40A, so a 40-amp breaker.
Round up to a standard size (next-size-up rule)
If the required rating doesn't match a standard size, NEC 240.4(B) allows the next higher standard rating — provided the circuit is 800A or less, doesn't serve multiple receptacle outlets, and the conductor ampacity doesn't already correspond to a standard rating. Example: a conductor with a 57A derated ampacity can be protected by a 60-amp breaker.
Verify the wire can handle it
The conductor's ampacity (after any derating) must be protected by the breaker. Use our breaker size calculator to run the whole calculation automatically, and double-check the wire on the wire size chart.
Single-Pole vs. Double-Pole Breakers
Single-pole breakersoccupy one panel slot, connect to one hot bus, and supply 120-volt circuits — lighting, receptacles, and small appliances. They're most commonly 15 or 20 amps.
Double-pole breakersoccupy two slots, connect to both hot buses, and supply 240-volt circuits — dryers, ranges, water heaters, HVAC equipment, EV chargers, and subpanel feeders. Both poles trip together via a common internal trip mechanism, so a fault on either leg disconnects the entire circuit. Common sizes run from 20 to 60 amps for appliances and 100 to 200 amps for feeders and mains.
The ampere rating means the same thing on both: a 30-amp double-pole breaker allows 30 amps to flow through each leg of the 240-volt circuit.
Frequently Asked Questions
What are the standard circuit breaker sizes?
Per NEC 240.6(A), the standard ampere ratings for fuses and inverse-time circuit breakers are: 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000, 5000, and 6000 amps. Additional standard ratings of 1, 3, 6, 10, and 601 amps apply to fuses. In homes, the most common sizes are 15, 20, 30, 40, 50, 60, 100, and 200 amps.
Is there a 75 amp breaker?
No — 75 amps is not a standard rating under NEC 240.6(A). The standard sizes jump from 70 to 80 amps. If a calculation lands at 75 amps, you would typically use a 70-amp breaker, or an 80-amp breaker where the next-size-up rule of NEC 240.4(B) applies (conductor ampacity of 75A protected by the next standard size, allowed for circuits 800A and under that don't supply multiple receptacle outlets). Nonstandard ratings are permitted by 240.6(A) but are not commonly manufactured.
What size breaker for a 240V circuit?
Voltage alone doesn't determine breaker size — the load's amperage does. A 240V circuit uses a double-pole breaker sized to the load: a 4,500W water heater draws about 18.8A and needs a 25 or 30-amp double-pole breaker with #10 copper; an electric dryer typically needs 30 amps; a range needs 40 or 50 amps; and an EV charger is sized at 125% of its continuous charging current. Calculate amps (Watts ÷ 240), apply 125% for continuous loads, then choose the standard size.
What is the most common breaker size in a home?
15-amp and 20-amp single-pole breakers are by far the most common. 15-amp breakers with #14 copper wire serve lighting and general receptacle circuits, while 20-amp breakers with #12 copper serve kitchens, bathrooms, laundry areas, and garages — all of which the NEC requires to be on 20-amp circuits. Most modern homes also have a 200-amp main breaker.
Can I replace a 15 amp breaker with a 20 amp breaker?
Only if the entire circuit is wired with #12 AWG copper or larger. NEC 240.4(D) limits #14 copper wire to a 15-amp overcurrent device, so putting a 20-amp breaker on #14 wire creates a fire hazard — the wire can overheat before the breaker trips. If a breaker trips repeatedly, the fix is to reduce the load or add a circuit, never to install a bigger breaker on the same wire.
Related Electrical Calculators
Breaker Size Calculator
Enter your load in watts or amps and get the correct standard breaker size, including the 125% continuous-load factor.
Calculate Breaker Size →Wire Size Chart by Amps
Quick wire size answers for common 30–200A circuits, from dryers to 200 amp services.
View Wire Size Chart →Wire Ampacity Chart
Full NEC Table 310.16 ampacities for copper and aluminum at 60°C, 75°C, and 90°C, with derating factors.
View Ampacity Chart →Branch Circuit Calculator
Size branch circuits per NEC Article 210 — conductor, breaker, and receptacle requirements.
Calculate Branch Circuits →