How many amps can #10 handle?

Number 10 copper handles 30 amps on a standard breaker. NEC 240.4(D) caps 10 AWG at 30 amps for ordinary branch circuits even though its table ampacity is 35 at 75C.

That makes 40 or 50 amps on #10 a code violation for normal circuits. The recurring exception is motor and air-conditioning equipment, where a larger breaker covers inrush while the equipment overload protects the wire.

Ten gauge is the workhorse for water heaters, dryers on short runs, and 30 amp RV receptacles.

On long runs the limit stops being the breaker and becomes voltage drop: past about 80 feet at full load, #10 starts giving back volts, and the next size up pays for itself.

Check both limits at once with the 10 gauge wire amps calculator.