Amperage Chart for Appliances: Breaker and Wire Sizing Guide

To properly size a branch circuit, divide the appliance wattage by the nominal voltage, apply a 125% multiplier if the load runs for three or more continuous hours, and select your breaker and wire gauge based on the NEC 60°C or 75°C ampacity columns. The most common residential circuits require 12 AWG copper wire on a 20-amp breaker for 1500W to 1800W appliances, and 6 AWG copper on a 50-amp breaker for standard electric ranges.

How to Read the Appliance Amperage Chart

This reference table translates common household appliance wattages into actionable circuit requirements based on the 2023/2026 National Electrical Code (NEC).

*Note: While a space heater is technically a portable plug-in device, running it on high for 3+ hours classifies it as a continuous load in practical thermal management, requiring a 20A circuit to prevent breaker nuisance tripping.

Quick-Jump Reference: Most Queried Appliance Loads

If you are bookmarking this page for jobsite or bench reference, these are the three most common DIY missteps regarding appliance amperage:

• The 1500W Space Heater Trap: A 1500W heater draws exactly 12.5A. On a standard 15A breaker, this leaves only 2.5A of headroom. If the heater runs for more than three hours, NEC 210.20(A) requires the breaker to be rated at 125% of the continuous load (12.5A x 1.25 = 15.62A). A 15A breaker will eventually thermal-trip. The Fix: Plug it into a dedicated 20A circuit wired with 12 AWG.
• The Microwave Nameplate Illusion: A microwave advertised as "1000W Cooking Power" actually draws significantly more from the wall due to magnetron inefficiency. Expect a 1500W to 1800W draw (12.5A to 15A). The Fix: Never share a 15A kitchen circuit with a microwave and a toaster; run a dedicated 20A line.
• EV Charger Continuous Load Math: A "40-Amp" EV charger draws 40A continuously. Multiplying by 1.25 yields 50A. The Fix: You must use a 50A breaker and 6 AWG copper wire (rated 55A at 75°C, but standard practice and termination limits align with the 50A breaker). Do not use 8 AWG wire.

The 80% Rule and Derating: Which Column Actually Applies?

The most frequent question regarding NFPA and NEC branch circuit sizing is which ampacity column to use when sizing wire, and how environmental factors change the math.

Which Column Applies to Your Installation?

Even if you pull 90°C-rated THHN wire in conduit, NEC 110.14(C) and 240.4(D) dictate that for conductors sized 14, 12, and 10 AWG, you must use the 60°C ampacity column for final overcurrent protection sizing. This is because standard residential breakers and receptacles are typically rated for 60°C terminations. Therefore, 12 AWG wire is strictly capped at 20 amps, regardless of its 90°C insulation rating.

For larger wires (8 AWG and above) connected to modern 75°C-rated terminals (like a main panel lug or a dedicated HVAC disconnect), you may use the 75°C ampacity column.

How Derating Rows Modify the Base Value

When you bundle more than three current-carrying conductors in a single raceway, or when ambient temperatures exceed 86°F (30°C), you must apply derating factors from NEC Table 310.15(B)(1) and 310.15(B)(2). These rows modify the base 90°C ampacity value downward to prevent the wire insulation from melting inside the conduit.

Example: You are running four current-carrying 12 AWG THHN wires in a conduit to feed two multi-wire branch circuits. 1. Start with the 90°C column base value for 12 AWG: 30A. 2. Apply the 80% derating factor for 4-6 conductors: 30A x 0.80 = 24A. 3. The wire is now thermally capable of handling 24A in the conduit. 4. However, because it is 12 AWG, NEC 240.4(D) still limits your breaker to the 60°C column maximum: 20A. The derating didn't force you to upsize the wire in this specific scenario, but if you were using 8 AWG wire with six conductors, the math would force an upsize to 6 AWG.

Decision Path: Sizing Your Breaker and Wire

Use this decision tree to arrive at a concrete breaker and wire pick for any appliance not explicitly listed in the main chart. For deeper load calculations, reference EC&M's guide on NEC Article 210 branch circuits.

Concrete Pick Example: You are installing a hardwired 240V baseboard heater rated at 2000W. 1. 2000W / 240V = 8.33A. 2. Heaters are continuous loads: 8.33A x 1.25 = 10.41A. 3. Next standard breaker size up is 15A. 4. 15A breaker requires 14 AWG copper wire minimum (though 12 AWG is highly recommended for 240V voltage drop mitigation). Final pick: 15A double-pole breaker, 12 AWG 2-conductor NM-B or THHN.

What This Amperage Chart Cannot Tell You

While this chart covers 90% of residential appliance sizing, it omits three critical engineering variables that require on-site calculation:

1. Voltage Drop Over Distance: NEC 310.15(B) informational notes and 210.19(A) recommend keeping voltage drop under 3% for branch circuits. If your electric dryer is 150 feet from the panel, 10 AWG wire will suffer severe voltage drop under 23A load, causing the motor to overheat. You must upsize to 8 AWG or 6 AWG purely for distance, even though the breaker remains 30A.
2. Motor Locked Rotor Amps (LRA): Appliances with large compressors (HVAC units, large shop dust collectors) draw 5 to 7 times their running amperage for a few seconds during startup. The chart lists running amps. You must size the breaker using the manufacturer's specified Maximum Overcurrent Protection (MOCP) value, which often utilizes time-delay or HACR-type breakers to survive the startup surge without nuisance tripping.
3. Local AHJ Amendments: Some municipalities require 20A circuits and 12 AWG wire for all general lighting and receptacle circuits, entirely eliminating the use of 14 AWG / 15A breakers in residential builds. Always defer to your local Authority Having Jurisdiction (AHJ) and the inspector's final word over general NEC baseline tables.