Motor Circuit & HVAC MCA/MOCP Calculator
Motor full-load current from Table 430.250, branch-circuit conductor ampacity at 125% of FLC, branch OCPD sizing by protection type, and combined HVAC equipment MCA/MOCP from nameplate RLA/BCSC data.
What it calculates
- Motor full-load current (FLC) by horsepower, voltage and phase
- Required branch-circuit conductor ampacity (125% of FLC)
- Branch-circuit OCPD size by protection type (inverse-time breaker, dual-element fuse, etc.)
- HVAC equipment Minimum Circuit Ampacity (MCA) and Maximum Overcurrent Protection (MOCP) from the largest motor's RLA/BCSC plus the other motors' FLAs
Typical inputs
- Motor horsepower, voltage, phase
- Protection/starting type
- For HVAC equipment: nameplate RLA or BCSC for the largest motor, FLA for additional motors
Frequently asked
Why is HVAC MCA/MOCP a separate calculation from a single motor's branch circuit?
Article 440 treats HVAC equipment with multiple motors (a compressor plus condenser fan, for example) as one combined load: MCA sums 125% of the largest motor's current plus 100% of the others, and MOCP is sized off that combined figure rather than each motor individually.
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