Mini Split Wiring Diagrams: 115V & 208V/230V Systems
Use these complete single-line schematics to map every conductor across all three stages of ductless installation: the service breaker panel, the exterior pullout disconnect, and the outdoor-to-indoor interconnecting communication block.
NEC Article 440 Single-Line Schematic: Dedicated branch breaker to outdoor disconnect pullout and compressor terminals.
1. Standard 208/230V (240V) Mini Split Wiring Diagram
Over 95% of residential ductless heat pumps in North America operate on 208/230V single-phase power. Because 240V is supplied across two out-of-phase 120V hot legs, no neutral wire is used:
| Conductor | Panel Connection | Disconnect Switch | Condenser Terminal |
|---|---|---|---|
| Line 1 (Hot) | Double-Pole Breaker (Pole A) | Line 1 In → Load 1 Out | Terminal L1 |
| Line 2 (Hot) | Double-Pole Breaker (Pole B) | Line 2 In → Load 2 Out | Terminal L2 |
| Ground (EGC) | Grounding Bus Bar | Grounding Lug (Bonded) | Ground Terminal (GND) |
2. 115V (120V) Mini Split Wiring Diagram
Common on compact 9,000 BTU and 12,000 BTU single-zone systems (e.g., DIY MrCool 115V models). Unlike 230V units, 115V mini-splits strictly require a neutral return wire:
| Conductor | Panel Connection | Disconnect Switch | Condenser Terminal |
|---|---|---|---|
| Line 1 (Black) | Single-Pole Breaker (15A/20A) | Line 1 In → Load 1 Out | Terminal L1 (Hot) |
| Neutral (White) | Neutral Bus Bar | Neutral In → Neutral Out | Terminal N (Return) |
| Ground (Green) | Grounding Bus Bar | Grounding Lug (Bonded) | Ground Terminal (GND) |
3. Interconnecting 14/4 Cable Diagram (Outdoor to Indoor)
The outdoor condenser supplies power and digital control signals to the indoor unit over a continuous 4-conductor tray cable (14/4 TC-ER):
| Terminal Number | Wire Color | Function & Signal Type |
|---|---|---|
| Terminal 1 | Black | Line 1 Power supply to indoor blower motor (115V or 230V). |
| Terminal 2 | White or Red | Line 2 / Neutral power return conductor. |
| Terminal 3 | Red or Yellow | Serial bi-directional DC microprocessor data communication. |
| Terminal GND | Green (Insulated) | Equipment grounding conductor. |
4. Frequently Asked Questions About Mini-Split Wiring Diagrams
How do I know if my mini-split is 115V or 230V from the wiring diagram?
Check the condenser terminal labels on the schematic sticker inside the wiring cover. If the terminals are marked L1 and N, it is a 115V single-phase unit requiring a neutral wire. If marked L1 and L2 (or L and N with a 208/230V label), it operates on 240V split-phase power across two hot legs without a neutral.
Does wire color matter as long as terminals 1, 2, 3 match on both ends?
Electrically, matching terminal numbers (1 to 1, 2 to 2, 3 to 3, and Ground to Ground) ensures the system operates. However, under NEC Article 250.119, the equipment ground conductor must strictly be green or green with yellow stripes. Crossing a green wire into Terminal 1 or 3 violates electrical code and creates a severe shock hazard.
Why is there a whip shown between the disconnect and condenser?
Inverter compressors vibrate slightly during heating and cooling cycles. Rigid metallic conduit (EMT or PVC) directly attached to the condenser chassis can crack, loosen fittings, or transmit acoustic motor hum into interior walls. A flexible, liquid-tight non-metallic conduit whip (LFNC) isolates vibration and provides weatherproof protection.
Step-by-Step Installation & Code Guides:
Need a practical step-by-step walkthrough? Read our How to Wire a Mini Split Guide, review our 14/4 Signal Wire Breakdown, or explore the Full Sizing Reference Matrix.