What Size Wire for 100 Amp Service: Copper vs Aluminum Sizing Chart?

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Here’s a complete HTML article answering the wire-size question for 100 amp service. It covers NEC 310.12 dwelling allowances, copper vs aluminum ampacity tables, grounding conductors, and common inspection pitfalls — all in a compact format ready to paste into WordPress.
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A 100-amp dwelling service usually needs 4 AWG copper or 2 AWG aluminum, while a full-ampacity 100A feeder calls for 3 AWG copper or 1 AWG aluminum.

For the full breakdown, see our best 100 Amp Service Wire guide.

A 100-amp service can be wired two different ways and both can pass inspection, because conductors supplying an entire one-family dwelling are allowed to be smaller than conductors that must carry a full 100 amps. Mixing up those two situations is one of the most common reasons a service fails inspection.

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Mo Maruf

Mo Maruf

Founder

I am a dedicated home cook and appliance enthusiast. I spend hours in my kitchen testing real-world storage methods, reheating techniques, and kitchen gear performance. My goal is to provide you with safe, tested advice to help you run a more efficient kitchen.