⚡ Key Takeaways<\/p>\n
- \n
- For a 20 amp circuit: use 12 AWG wire (yellow sheathed NM cable in the US).<\/li>\n
- For a 15 amp circuit: use 14 AWG wire (white sheathed NM cable).<\/li>\n
- Always match the wire gauge to the breaker rating \u2014 never use a thinner wire than specified.<\/li>\n<\/ul>\n<\/div>\n
Wire Gauge and Amp Rating Quick Reference (US)<\/h2>\n
In the US, wire gauge is measured in AWG (American Wire Gauge) \u2014 confusingly, lower numbers mean thicker wire:<\/p>\n
- \n
- 15 amp circuit<\/strong> \u2192 14 AWG wire (white NM cable sheath)<\/li>\n
- 20 amp circuit<\/strong> \u2192 12 AWG wire (yellow NM cable sheath)<\/li>\n
- 30 amp circuit<\/strong> \u2192 10 AWG wire (orange NM cable sheath)<\/li>\n
- 40 amp circuit<\/strong> \u2192 8 AWG wire<\/li>\n
- 50 amp circuit<\/strong> \u2192 6 AWG wire<\/li>\n<\/ul>\n
Why Does Wire Gauge Matter?<\/h2>\n
A wire’s current-carrying capacity is determined by its cross-sectional area. Thinner wire has higher electrical resistance. When too much current flows through a thin wire, the wire heats up. The circuit breaker is calibrated to trip at a specific current level \u2014 if you use 14 AWG wire on a 20 amp breaker, the wire can overheat and potentially catch fire before the 20 amp breaker trips. The breaker is protecting the wire, not the other way around.<\/p>\n
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<\/p>\nWhat Gauge Wire for Specific Applications?<\/h2>\n
Kitchen Circuits<\/h3>\n
Kitchen small appliance circuits must be 20 amp (12 AWG) per NEC requirements. Refrigerators should have a dedicated circuit<\/a>; other large kitchen appliances (dishwasher, microwave) should also be on dedicated 20 amp circuits where possible.<\/p>\n
Bathroom Circuits<\/h3>\n
At least one 20 amp circuit serving only bathrooms is required by the NEC. 12 AWG wire.<\/p>\n
EV Charger (Level 2, 7.2kW)<\/h3>\n
A 32 amp EVSE requires 6 AWG wire on a 40 amp breaker. Some installations use 8 AWG on a 40 amp breaker \u2014 check the specific charger’s installation manual for requirements. For more on EV charger installation, see our guide on EV charger installation time<\/a>.<\/p>\n
Dryer Circuit<\/h3>\n
Most electric dryers require a 30 amp, 240V circuit using 10 AWG wire with both a black and red hot conductor plus neutral and ground.<\/p>\n
UK Wire Sizing<\/h2>\n
UK wiring uses metric cross-sectional area (mm\u00b2) rather than AWG. The standard sizes for common circuits are: 1.0mm\u00b2 for lighting circuits (up to 10A), 2.5mm\u00b2 for ring main power circuits (protected by 32A RCD\/MCB), and 4mm\u00b2 or 6mm\u00b2 for high-draw appliances (showers, cookers, EV chargers \u2014 sized to the specific current draw).<\/p>\n
- 20 amp circuit<\/strong> \u2192 12 AWG wire (yellow NM cable sheath)<\/li>\n
- 15 amp circuit<\/strong> \u2192 14 AWG wire (white NM cable sheath)<\/li>\n