What Size Wire for a Mini-Split (Ductless) System?
Wire and breaker sizing for a Mini-Split (Ductless) System — the typical 240V circuit, plus the code details (NEC Article 440) 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.
On a 20A 240V circuit at 75°C terminations.
Protected by a 20A breaker (NEC 240.6).
Mini Split current varies by model. The size above is the common case — always size the conductor to the unit’s nameplate rating / Minimum Circuit Ampacity (MCA) and protect it at the labeled maximum breaker/fuse.
Mini Split Circuit Details
- Ductless mini-splits are sized to the nameplate MCA/max fuse — commonly 15–30A (14–10 AWG copper).
- Use a HACR-rated breaker no larger than the label’s maximum fuse/breaker.
- Most single-zone 9k–24k BTU units use a 15A or 20A 240V circuit.
Long run to your mini split?
Over distance, voltage drop can require a larger wire than the table above. See the 20A wire size by distance:
Size it for your exact install
Open the calculator pre-filled with 20A at 240V to add distance, material and temperature.