Electrical Load Calculator
Calculate RLA, LRA, breaker size, and wire gauge
⚠️ Always Verify Equipment Nameplate
These are estimates based on typical values. Before installation, you MUST check the equipment nameplate for:
- MCA (Minimum Circuit Ampacity) — determines minimum wire size
- MOP/MOCP (Maximum Overcurrent Protection) — determines maximum breaker/fuse size
- RLA/FLA (Running/Full Load Amps) — actual rated current draw
- LRA (Locked Rotor Amps) — actual starting current
Using estimates instead of nameplate values can result in nuisance tripping, undersized wiring, or code violations.
Advanced Options (Power Factor & Efficiency)
Typical: 0.80-0.90 for compressor motors
If known, provides more accurate estimate
Calculation Results
Calculations based on:
• Basic: RLA ≈ Tonnage × Amps/Ton (varies by voltage/phase/PF)
• With EER: RLA = (Tons × 12000) ÷ (EER × V × PF × √3) for 3Φ
• LRA ≈ RLA × 4~7 (varies by compressor type)
• Breaker ≥ RLA × 1.25 (per NEC 440.22)
LRA Multipliers: Scroll ×6, Reciprocating ×7, Rotary ×6.5, Inverter ×4 (soft start)
Wire Size Reference (Copper)
| Ampacity | AWG | mm² |
|---|---|---|
| 15A | 14 AWG | 2.5 mm² |
| 20A | 12 AWG | 4 mm² |
| 30A | 10 AWG | 6 mm² |
| 40A | 8 AWG | 10 mm² |
| 55A | 6 AWG | 16 mm² |
| 70A | 4 AWG | 25 mm² |
| 85A | 3 AWG | 35 mm² |
| 95A | 2 AWG | 35 mm² |
| 110A | 1 AWG | 50 mm² |
| 125A | 1/0 AWG | 50 mm² |
Important: Always verify with local electrical codes and equipment nameplate data. These are estimates for general guidance only.