What Size Wire for a Shed?
Wire and breaker sizing for a Shed — the typical 240V circuit, plus the code details (NEC 310.16) that change the answer.
Calculations are built on the 2023 National Electrical Code (NEC) and cross-checked against the published code tables. How we verify. Last reviewed June 2026.
Copper
10 AWG
On a 30A 240V circuit at 75°C terminations.
Aluminum
8
Protected by a 30A breaker (NEC 240.6).
Voltage
240V
Breaker
30A
Connection
Hardwired
GFCI
Not required
Shed Circuit Details
- Small sheds often run on a 30–60A feeder; 30A (10 AWG) suits lights and a few outlets.
- Long underground runs make voltage drop the deciding factor — check the distance.
- A detached shed sub-panel needs a disconnect and grounding electrode.
Long run to your shed?
Over distance, voltage drop can require a larger wire than the table above. See the 30A wire size by distance:
Size it for your exact install
Open the calculator pre-filled with 30A at 240V to add distance, material and temperature.