12 AWG cable is typically used for general indoor electrical wiring and circuits, particularly for outlets and appliances requiring up to 20 amps of current. The ampacity of a 12 AWG copper wire, including 12/2, 12/3, and 12/4, is between 20 and 30 Amps. The breakdown according to the insulation is the following:

• 12 AWG Copper with 60°C insulation (like TW, UF): 20 Amps
• 12 AWG Copper with 75°C insulation (like RHW, THHW, THWN): 25 Amps
• 12 AWG Copper with 90°C insulation (like THHN, XHHW): 30 Amps

What Is The Ampacity of 12 AWG Aluminum Wire?

Aluminum has a lower conductivity than copper, which impacts the ampacity of 12 AWG aluminum wire. Here is the breakdown:

• 12 AWG Aluminum with 60°C insulation (like TW, UF): 15 Amps
• 12 AWG Aluminum with 75°C insulation (like RHW, THHW, THWN): 20 Amps
• 12 AWG Aluminum with 90°C insulation (like THHN, XHHW): 25 Amps

Common Applications of 12 AWG Wire

1. General Indoor Wiring: 12 AWG cables are frequently used for general-purpose home wiring. This includes lighting circuits and standard outlets in living rooms, bedrooms, and other rooms with high-ampacity demands.
2. Kitchen and Bathroom Outlets, as well as other outlets with moderate power capacity.
3. Outdoor Lighting: In size 12, cables are used in garden lights, security lights, and other moderate-load lighting fixtures.
4. Underground Feeder Lines: When used with appropriate insulation (like UF-B), 12 AWG wire is suitable for some underground feeder lines to outdoor lighting or power outlets.
5. Air Conditioning Units: Smaller, room-sized air conditioning units often use 12 AWG wiring, especially close to the power source.
6. Small Electric Heaters: This gauge is often used for wiring smaller electric heaters.
7. Ceiling Fans: 12 AWG wire is commonly used for ceiling fan installations, particularly if the fan includes a light kit or is part of a larger lighting circuit.

Common Types of 12 AWG Cable

• THHN/THWN: This building wire is widely used in both residential and commercial settings for wiring light fixtures, outlets, and small appliances. 
• NM-B Romex: In size 12, this indoor non-metallic wire is used in residential indoor wiring for standard lighting circuits and power outlets in dry locations.
• UF-B (Underground Feeder Type B): This outdoor direct burial wire is used in garden lighting, power to detached garages, and low-ampacity direct burial applications.
• XHHW: 12 AWG XHHW is used for heat and moisture-resistant applications.
• MC (Metal Clad): In commercial and industrial applications, 12 AWG MC cable is used for wiring power, lighting, and control circuits as long as additional protection provided by the metal sheath is beneficial.
• TECK90: This rugged cable is used in industrial settings for machinery, control circuits, and power distribution. This is a Canadian standard for cables used in harsh environments.
• Speaker Wire: 12 AWG speaker wire is common for longer cable runs and high-power audio systems.