Electrical / Free field reference
Wire Gauge Reference: 14, 12 & 10 AWG Copper
For ordinary applications under NEC 240.4(D), the general copper small-conductor overcurrent limits are 15 A for 14 AWG, 20 A for 12 AWG, and 30 A for 10 AWG. These limits are not a complete wire-sizing calculation.
Scope: 14–10 AWG copper only; 2023 NEC reference. General small-conductor protection limits, subject to specific code exceptions. Aluminum, cable assembly rules, correction factors, and load calculations are outside this lookup.
Quick reference
| Gauge | General overcurrent limit | Approx. solid conductor diameter |
|---|---|---|
| 14 AWG | 15 A | 0.064 in |
| 12 AWG | 20 A | 0.080 in |
| 10 AWG | 30 A | 0.101 in |
Before you use the result
- A 75°C or 90°C ampacity column does not by itself allow a larger breaker for these small conductors.
- Check load, continuous-load requirements, termination ratings, wiring method, ambient temperature, conductor grouping, voltage drop, and equipment instructions before choosing a conductor.
- Diameter is bare solid copper, not the outside diameter of insulated cable. Do not use it to size conduit.
Sources & edition notes
This is an independent HandySuite reference. The linked publisher’s code or equipment documentation governs the work.
Common questions
What gauge copper wire is commonly associated with a 20 A circuit?
12 AWG copper has a general 20 A small-conductor protection limit. That is a starting reference, not confirmation that it suits the actual load, installation, or run length.
Can I use the same limits for aluminum?
No. This reference is limited to copper. Aluminum has different rules and connection requirements.