Side-by-Side Comparison
Electrical & Wiring
Circuit Breaker Sizes & Amperage vs. Wire Ampacity Ratings
Comparing 2 standards across 19 specifications. 19 key differences identified.
Comparing:
Circuit Breaker Sizes & Amperage
Wire Ampacity Ratings
Residential and commercial circuit breakers are standardized under National Electrical Code (NEC Article 240) and UL 489 into standard continuous trip ratings (15A, 20A, 30A, 40A, 50A, 60A, 100A, 200A), single-pole (120V) vs double-pole (240V) formats, and mandatory AFCI/GFCI protection types.
National Electrical Code (NEC) Table 310.16 establishes allowable conductor ampacities based on conductor material (Copper vs Aluminum), ambient temperature, and insulation thermal ratings (60°C TW/NM-B Romex, 75°C THWN, 90°C THHN).
Specification Comparison Table
19 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standards
|
NFPA 70 (NEC) / UL 489 / NEMA AB 1 (Circuit Breakers) | — |
|
15-Amp Single Pole (120V)
|
Wire Gauge: 14 AWG Copper | Standard residential lighting and general bedroom/living outlets | — |
|
20-Amp Single Pole (120V)
|
Wire Gauge: 12 AWG Copper | Kitchen countertop, bathroom receptacles, laundry, garage, workshop | — |
|
30-Amp Double Pole (240V)
|
Wire Gauge: 10 AWG Copper | Electric clothes dryers, 30-gallon water heaters, small RV hookups | — |
|
40-Amp Double Pole (240V)
|
Wire Gauge: 8 AWG Copper | Electric cooking ranges, cooktops, heat pump auxiliary heat | — |
|
50-Amp Double Pole (240V)
|
Wire Gauge: 6 AWG Copper | Level 2 EV charging (NEMA 14-50), commercial cooking ovens | — |
|
60-Amp Double Pole (240V)
|
Wire Gauge: 4 AWG Copper (or 6 AWG THHN) | Central air conditioning compressors, sub-panel feeds | — |
|
100A–200A Main Service
|
2/0 AWG Copper / 4/0 AWG Aluminum | Main residential service disconnect panel | — |
|
80% Continuous Load Rule
|
NEC 210.20: Continuous loads (operating 3+ hours) must not exceed 80% of breaker rating (e.g. 16A max on 20A breaker) | — |
|
Governing Code
|
— | NFPA 70: National Electrical Code (NEC) Table 310.16 |
|
Small Conductor Overcurrent Rule (NEC 240.4D)
|
— | 14 AWG Cu: Max 15A | 12 AWG Cu: Max 20A | 10 AWG Cu: Max 30A |
|
14 AWG Copper (NM-B / Romex)
|
— | 15 Amps (60°C column applied per NEC 334.80) |
|
12 AWG Copper (NM-B / Romex)
|
— | 20 Amps (Standard residential branch circuit) |
|
10 AWG Copper (NM-B / Romex)
|
— | 30 Amps (Clothes dryers, 30A water heaters) |
|
8 AWG Copper (75°C THWN / NM-B)
|
— | 40A (NM-B 60°C) / 50A (THWN 75°C conduit) |
|
6 AWG Copper (75°C THWN / NM-B)
|
— | 55A (NM-B 60°C) / 65A (THWN 75°C conduit) |
|
4 AWG Copper (75°C THWN)
|
— | 85 Amps (Residential subpanel feeder) |
|
2 AWG Copper (75°C THWN)
|
— | 115 Amps (100A subpanel / main feeder) |
|
4/0 Aluminum (75°C XHHW / SE)
|
— | 180 Amps under standard NEC Table 310.16 ampacity; commonly used as the minimum conductor for a 200A dwelling service under NEC's separate service-conductor allowance (Table 310.12, formerly 310.15(B)(7)) |
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