Read the nameplate before you buy wire
Every outdoor unit lists minimum circuit ampacity (MCA) and maximum overcurrent protection (MOCP). Those numbers — not a YouTube guess — set breaker size and wire gauge. Undersized wire is a fire risk; oversized breakers that ignore the label are a code failure.
Size the equipment with the mini-split calculator first, then match electrical to that model’s installation sheet.
Common DIY electrical checklist
If your panel is full or you are unsure about load calculations, hire a licensed electrician for the circuit even if you mount the heads yourself.
- Dedicated circuit — do not share with shop tools or a dryer
- Correct voltage: many 12k–24k units need 208/230V; some small kits are 115V
- Breaker size at or below MOCP on the nameplate
- Copper conductors sized for MCA and run length (voltage drop)
- Outdoor disconnect within sight of the condenser (local code)
- Whip / conduit from disconnect to unit per manufacturer
- Proper grounding and bonding
Indoor power and communication
Most ductless systems power the outdoor unit and send low-voltage or manufacturer communication cable to the indoor head — follow the wiring diagram exactly. Mixing thermostat wire gauges or skipping the disconnect “to finish Saturday” causes warranty and inspection problems.
Next steps in the project
Plan clearances in indoor and outdoor placement, choose a kit type in pre-charged DIY kits, then follow install basics. Full map: DIY mini-split roadmap.